International Conference
Crop improvement, Ideotyping, and Modelling for African
Cropping Systems under Climate Change - CIMAC
University of Hohenheim, 7-9 February 2011
Book of Abstracts
Impressum
The CIMAC conference is organized by the Department of Plant Production
and Agroecology in the Tropics and Subtropics, Section Crop Water Stress
Management, Faculty of Agriculture, University of Hohenheim.
Organisation Committee:
Prof. Dr. Folkard Asch
Dr. Marcus Giese
Katja Sodtke
Sinem Karagöz
University of Hohenheim
Institute for Plant Production and Agroecology of the Tropics and Subtropics
Garbenstraße 13
D-70593 Stuttgart
Email: cimac@uni-hohenheim.de
Phone: ++49 (0)711 459 24189
Fax: ++49 (0)711 459 24207
Online version available under:
http://www.risocas.de
Acknowledgement
We are very thankful for the support of the
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ),
Federal Ministry of Economic Cooperation and Development (BMZ),
Deutsche Forschungsgemeinschaft (DFG),
fiat panis foundation,
Tropenzentrum at the University of Hohenheim.
2
Content
1
2
Preface……………………………………………………………..
Introduction…………………………………………………………
3
Crop improvement
Rice……………………………………………………………………….
Maize, Sorghum and other crops……………………………………..
3
Traits for ideotypes
Phenology………………………………………………………………..
Morphology………………………………………………………………
Physiology……………………………………………………………….
4
14
21
30
41
47
Crop modelling for ideotype development
Crop modelling…………………………………………………………..
Ideotype development………………………………………………….
5
4
5
Poster
Crop improvement………………………………………………………
Traits for ideotypes, modelling………………………………………...
50
57
67
75
3
Preface
International Conference on Crop improvement,
ideotyping, and modelling for African cropping
systems under climate change - CIMAC
Climate Change threatens staple food production and human livelihoods,
particularly in vulnerable environments in Africa. Poorly adapted cropping
systems increase the risk for poverty and hunger. Existing genotypes adopted
to local conditions may not be suited for cropping systems responding to future
climatic conditions. Models based on genotypic traits for ideotyping varieties to
fit specific environmental conditions will accelerate crop improvement required
to adapt systems to climate change.
CIMAC addresses possibilities for genotypic adaptation via identification of
suitable morpho-physiological traits, breeding strategies, and modelling that
allows for extrapolative evaluation of climate change scenarios in view of
genotypic adaptation mechanisms. By this the basis for tactical and strategic
decision making to adapt African agriculture to climate change will be
strengthen. The CIMAC is organized into three main conference themes:
• Crop improvement strategies for genotypic adaptation to climate change
• Traits for ideotypes to adapt African crops to climate change
• Crop modelling for ideotype development
The idea to offer an international conference was developed in the frame of the
RISOCAS project (Developing rice and sorghum crop adaptation strategies for
climate change in vulnerable environments in Africa) which is part of the
research initiative “Adapting African Agriculture to Climate Change” funded by
GIZ/BMZ from 2008–2011. The RISOCAS project was carried out in cooperration with AfricaRice (Saint Louis, Senegal), IER (Bamako, Mali), FoFiFa
(Madagascar) and CIRAD (Montpellier, France).
During field experiments in Senegal (irrigated rice), Mali (sorghum) and
Madagascar (upland rice) 10 varieties of each crop were subjected to multiple
environments created by different locations and staggered planting dates in
order to analyze crop performance under varying environmental conditions
covering a range of expected climate change scenarios. The positive
discussions on first results indicated a broad interest of the scientific
community, which encouraged us to initiate an international conference - the
CIMAC.
We hope that the conference will offer a platform for the exchange of ideas,
concepts and experiences. We want to thank all participants for visiting the
CIMAC conference and wish you three pleasant and fruitful days at the
University of Hohenheim.
The CIMAC conference organisation
4
Introduction
Opportunity in Change : Key Crops Rice and
Sorghum
MICHAEL DINGKUHN
CIRAD, BIOS Department, Montpellier, France
Climate change (CC) is perceived either as a menace to our livelihood, peace
and environment, or as a collective hype that will probably go away. But it can
also be seen as change per se, real or imagined, in the conditions that set the
frame for all human activities. The perception of such conditions has driven
technological development ever since. Change in the conditions, or change in
their perception as societal needs evolve, is thus a driving force of innovation.
This is particularly true in agriculture, which a priori is not a struggle against
nature, but rather an intelligent collaboration with nature to produce food and
other things.
Of course CC is also a threat. Regional changes in precipitation will, for
example, bring hardship to many poor regions (Fig. 1) and will require profound
local changes of systems and geographical migration of crops. Such changes
necessarily meant humanitarian and civilizational crises in pre-scientific and
pre-globalization times. They will still mean that today in many parts. But as
researchers we know that change, if it is gradual and not disruptive, also
means: Mobilization of economic and technical creativity, Readiness for
adoption of new solutions by stake holders including farmers… In short: When
frame conditions change there is a chance for renewal, and readiness to
question habitual dogmas.
Rice and sorghum systems together cover a large spectrum of situations with
very different vulnerabilities and opportunities. The problematic of rice hinges
on this crop’s high water requirements and good adaptation to excess water,
providing remarkable sustainability and productivity under flooded conditions:
easier weed control, stability of soil pH and fertility, salinity control,
transpirational cooling and more. The combination of CC and increasing
competition for water conspire against the flooded rice crop. Water-saving
management and breeding objectives are likely to have negative trade-offs
because they aim at taking the crop out of its natural niche of adaptation. In
fact, upland rice already represents such a compromise, and it is among the
most vulnerable crops in terms of CC impacts. Should we “leave rice in the
swamp” where it came from? No: (1) because biotechnology is moving fast
towards molecular breeding for “new crops”, requiring the development of
ideotype and ecosystem management concepts now; and (2) because rice as a
food has such a specific appeal and importance that it cannot be easily
substituted.
5
Introduction
Sorghum, in contrast to rice, is adapted to many components of future CC
scenarios: drought tolerant, water and nitrogen use efficient, heat tolerant,
lodging resistant, and potentially highly productive through C4 metabolism and
short duration (unless photoperiod-sensitive). Existing genetic diversity
probably also includes tolerance to water logging. Sorghum is in many ways
similar to maize but derives much of its superior drought resistance from its
unprotected panicle, thus avoiding the ANI effect related to silk elongation. (In
turn, sorghum is susceptible to panicle pests and diseases, for the same
reason.) A vast, unexploited potential exists to further improve sorghum
genetically, including greater yield potential and plant types for multiple uses
including food (grain), (bio-)fuel, feed and fiber (FFFF). Also, improvement of
milling and food quality should be possible and will be necessary if sorghum is
to partially substitute for other, less well adapted staples such as maize or
upland rice.
But genetic improvement of sorghum alone is not sufficient to achieve broader
adoption and productivity increase, as experience in Africa shows. In fact, a
closer look at what it takes to adapt semi-arid agriculture in developing
countries to CC shows that we basically have to enhance development. The
two most vulnerable societal groups are traditional subsistence farmers
(because CC may force them to become even more risk aversive, but they lack
the land resources to do so) and the urban poor (because food prices will
6
Introduction
increase). Subsistence farmers faced with increasing climatic variability in
semi-arid zones will have to cope with the prospect of frequent crop failure, for
them an existential problem. They will have to intensely benefit from the good
years and go commercial in order to save money to survive the bad years.
Therefore they will need insurance mechanisms, micro-credits and tactically
applied bumper-yield technology to cope with the ups and downs, like their
farmer-colleagues in Australia. And they will need seasonal forecasts and
decision aids, along with improved physical access to markets and extension
services. Development, in short. And rapidly. Improved plant types of sorghum
and millet will contribute to this, but not in the absence of an integrated
development strategy as outlined above.
The slightly wetter zones at lower latitude (dry and moist savannah) have the
physical potential of becoming Africa’s bread basket, even under CC scenarios.
Here, crops currently produce vastly below their potential for a number of
genetic, agronomic and societal reasons. Sorghum has a great production
potential but traditional low-yielding materials are still preferred because their
photoperiod sensitivity helps them escape from excess moisture (panicle
diseases!) and enables flexible calendars. Breeding, aided by projects like
RISOCAS, should make a large difference, but again this will also require
structural economic changes for achieving positive impact.
The main two messages from this analysis are that (1) adaptation to CC of
agricultural systems in developing countries essentially requires accelerated
development to make innovations work on a commercial and technologically
more effective basis; and (2) great innovative potential resides in rice and
particularly sorghum genetic improvement towards new adaptations and new
uses, drawing from biotechnological advances. I will close this reflection with
an outlook on what these plant type improvements may be like.
In rice, conventional breeding has been struggling after the Green Revolution
to make progress in two crucial areas, namely further improvement of yield
potential for irrigated rice, and drought resistance for upland rice. It is too early
to judge whether the C4-rice project will achieve its goals, but in terms of
abiotic stress tolerance new advances are coming up, resulting from both the
new CC focus and discoveries made in genomics research. (I am not citing
sources because these are unpublished results.) For example, a gene for root
angle was discovered in Japan (Dro1) which conveys significantly improved
drought avoidance through a deeper root system when selectively introgressed
into a high-yielding lowland indica background. Even more exciting is the
recent discovery made in France that the stress susceptible japonica lowland
variety Nippon Bare develops absolutely stunning drought, salinity, chilling and
oxidative stress tolerance when transformed with a regulatory gene from a
halophytic grass species. This gene, which has no phenotypic impact under
stress-free conditions, seems to orchestrate stress responses and thereby
mobilizes adaptations that are latently present in the wild type (WT) but are not
or ineffectively expressed. The prospect of achieving stress tolerance through
7
Introduction
gene network “master genes” from other species (that are more effective than
their orthologs in the WT) is truly exciting, and so is the apparent fact that major
adaptations reside silently in genomes of common cultivars and thus need not
be introgressed from other sources. Lastly, it is worth mentioning that rice can
achieve substantial heat stress avoidance through transpirational cooling,
namely on the sterility-prone panicle. Nothing is known on the genetics of this,
but this trait, in combination with some complementary architectural and
phenological traits, as well as a trait for anthesis happening early in the day,
might constitute an effective answer to the heat stress issue.
For sorghum, it was emphasized that this crop already possesses remarkable
adaptations to conditions brought about by CC, although terminal drought
resistance can be further enhanced through stay-green and other traits. Much
more important advances can be expected from the development of new
ideotypes drawing from the great morphological and phenological diversity and
phenotypic plasticity of the species. Sorghum, originally a grain crop whose
strong stems also found mechanical use in farm households, can be developed
into high-value forage, sugar juice crops or sugar- or biomass-based fuel crops.
Sorghum’s high photosynthetic rate even enables combinations of these uses
with remarkably small trade-offs. These features will probably give sorghum a
key role in resolving the combined problematic of CC, the need for enhanced
food and feed production, and the demand for biological sources of fuel.
Natural genetic diversity exists to adapt the crop to cooler and hotter climates,
as well as to water logging which is frequently a problem in the wet season in
semi-arid regions. And bacterial transgenes are available that potentially further
increase the sugar production in internodes (sucrose isomerase, trapping its
product isomaltulose in parenchyma vacuoles). Developing new crop types
from sorghum is thus a matter of investment and good ideas, and not a matter
of genetic resources.
I will end this overview with the conviction that tropical, agricultural adaptation
to CC can build on many potential, innovative solutions, from developing new
crops to improved seasonal forecasts. But they generally work only if there are
massive and rapid advances in agricultural development per se, requiring
political will, social stability and investment. There will be a lot of structural
change and it will be in part disruptive. But the change will be a source of great
scientific discovery and technological innovation.
Contact: michael.dingkuhn@cirad.fr
8
Introduction
Crop improvement, ideotyping and modelling under
climate change
S.C. CHAPMAN1, K. CHENU2, M.F. DRECCER1, D. JORDAN2, G.L. HAMMER2,
K.B. W OCKNER1, B. ZHENG1
1
CSIRO Plant Industry/Climate Adaptation Flagship, Australia
Centre for Plant Science, QAAFI, School of Agriculture and Food Sciences, The University of
Queensland
2
Introduction
The year 2050 is two to five full cycles of plant breeding from the present.
Given that it takes 3 to 20 years to develop a new cultivar, this is not a
substantial time period in which to develop improved adaptation. Averaged
across many crops, environments and traits, plant breeding has delivered
productivity improvements of about 1 to 4% per year in the last century, usually
in the context of a slowly-changing set of target environments. With rapid
improvements in genotyping and phenotyping technologies, breeding programs
currently have an impressive array of tools to apply to specific challenges. The
climate challenge for breeders is to define what environments will occur, which
ideotypes will suit these environments, and how to deploy genetic resources to
adapt to climate change.
Design of crop improvement programs
Progress in crop improvement is limited by the ability to identify favourable
combinations of genotypes (G) and management practices (M) in the relevant
target environments (E). With climate change, this progress is even less
certain, given that breeders do not know what future environments will exist
within the target region for a given breeding program. One might consider the
breeding challenge of ‘future climate’ as being similar to the challenge of
adapting a crop to a new geographical region. Radical changes in the variability
of environmental stresses (e.g. heat stress, drought), and increases in pest and
disease pressure would have two major effects: (1) to overcome existing
genetic adaptation and (2) to directly reduce the efficiency with which breeders
can identify adapted lines, i.e. the ranking of varieties becomes confounded by
effects of management, season and location (Genotype x Environment
interaction). The options for plant breeding programs to adapt include the
introduction of new more diverse pools of germplasm, and to consider whether
to focus on the development of specific or broad adaptation in released
cultivars.
At the core of typical plant breeding programs (Fig. 1), empirical crop
improvement measures the phenotypic performance of large segregating
populations in multi-environment trials and applies quantitative genetic theory
to choose superior individuals for selection and further crossing. This approach
is successful, but it is expensive and samples only a limited number of the
9
Introduction
possible environments. Within the core breeding program, this approach does
not consider other phenotypes (‘ideotypes’) that might be found if the breeder
was to sample germplasm outside the current breeding population. Breeding
programs typically develop pools of parental germplasm that are suited to their
2
geographical target range – from small regions (10s of km ) up to entire
countries or ecological zones. When new threats to production arise, breeding
programs need to identify new sources of genetic variation, e.g. from the
germplasm ‘banks’ of international institutes i.e. breeders anticipate needs for
new germplasm by developing small breeding projects on the side of their core
program (Fig.1). For complex traits like drought adaptation, utilising novel
sources takes 10 to 20 years to be delivered to farmers as new cultivars. The
useful new traits are then combined into existing cultivars that have all the
other desirable attributes (e.g. market quality), whether the cultivars are to be
conventionally-bred or developed through genetic engineering to utilise ‘singlegene’ traits.
Figure 1: Generic breeding program.
Molecular technologies have allowed the focus of practical crop improvement
to shift from the level of the individual (genotype) to the level of genomic region
(quantitative trait locus - QTL) and even gene. The capability to inexpensively
and densely map genomes is enabling molecular breeding strategies, but the
challenge for a breeder remains – how to define and detect suitable ideotypes
for ‘unknown’ environments. Further, the applicability of these breeding
strategies to complex traits such as yield, is limited by context-dependent gene
effects (gene-gene and gene-environment interactions), which constrain the
10
Introduction
power of predicting phenotype from knowledge of the genetic composition of an
individual. It is still possible to design molecular breeding strategies for complex
traits that, on average will outperform phenotypic selection. This requires geneto-phenotype (G-to-P) models of the traits that are able to account for the
context-dependent effects (e.g. Hammer et al. 2006). In the case of
physiological adaptation, there are roles here for crop simulation models to
assist in defining target ideotypes. However, first they must be able to
characterise the environmental challenges, and their occurrence and severity in
the breeding program region.
Defining and measuring ideotypes for climate change
As others have shown for Australia (e.g. Howden et al. 2007), the winter and
summer grain crops in Australia will likely experience warmer temperatures,
which translate into shorter crop growing seasons if current cultivars are used.
For wheat, in the absence of adaptive measures, a temperature increase of up
to 2°C during the reproductive period has been calculated to offset the benefit
of elevated CO2 levels. Many crop processes are also directly affected by brief
extreme weather episodes, especially when they coincide with the time of
flowering, e.g. heat stress in wheat and sorghum directly disrupts reproductive
processes leading to reduced grain number and poorly-filled shrivelled grains
(e.g references in Reynolds et al. 2010). Such stress episodes are anticipated
to increase with climate change.
To examine ideotypes for ‘future’ environments, we are using existing climate
forecast models to downscale climate change effects to single locations, for a
range of prediction scenarios. For example, Figure 2 shows how current
stations (start of the arrows) will in a 2050 future represent different stations
further south in Australia. This is based on a heat and frost stress index over
the cropping season, and is currently being expanded to compare wheat and
sorghum simulations for current and future climates. Our focus is to determine:
1. In what ways will conditions around flowering change with climate and
what will be the optimal flowering periods of the year? How will
management and cultivar adapt?
2. What levels of heat (and frost) stress can be expected and where?
3. What will be the impact on breeding programs of increased variability of
environments? i.e. will the heritability of trials be reduced and confound
our ability to identify superior cultivars?
4. To what extent can current genotypes adapt to these environments and
what changes in phenotype are needed?
11
Introduction
Figure 2: Current stations which represent ‘future climate’ stress patterns for
2050 A2 scenario.
In breeding, it is always challenging to determine which ideotypes are best –
simply because and pair of cultivars will usually vary for many traits other than
the specific contrast being compared. This is where crop simulation models are
useful as they allow all of the other traits to be held constant, while comparing
two values of an ‘ideotype’ trait (Porter and Semenov 2005).
Modelling breeding for climate change - smart physiology plus smart
breeding
There are a range of approaches for G-P prediction for complex traits operating
at broad levels of biological organisation. Gene network models have potential
to account for gene context dependencies but require advanced knowledge of
network structure and dynamics. However, the issue of scaling from network to
whole plant phenotypic response remains, unless direct associations exist, as
for example with transition to flowering. Functional whole-plant models (crop
models) have potential to account for environment context dependencies as
they attempt to encapsulate the dynamic plant-environment interactions. It is
plausible to link the vector of coefficients defining the plant characteristics in a
whole-plant model to genomic regions, but the issue of scaling from these
coefficients to gene level can be problematic, e.g. as some of these coefficients
are not related to an easily seperable eco-physiological process. Our current
projects are extending this work to study how genetic diversity in trait response
and changes in breeding systems might best allow adaptation to climate
change environments in Australian cereal cropping systems.
The complexity of the breeding process makes it challenging to re-design and
improve. Genetic simulation provides the tools to this. In previous research, we
have combined biophysical simulation models of crop growth with simulation
12
Introduction
models of the breeding process. This allows us to construct sets of crosses,
estimate the growth and yield of new genotypes and identify breeding
strategies that can most quickly deliver the new cultivar. The specific
advantage of biophysical models is that we can simulate how a cultivar would
grow in an existing climate, or in some ‘future’ climate, whatever that may be.
Hence, we can determine the impact of future climates on how well breeding
programs can deliver new cultivars that are suited for the future production
systems. This allows us to evaluate the effectiveness of both conventional
phenotypic breeding programs (affected by variation in environments which
reduces precision of measurement), as well as to design molecular and
genomic selection strategies to accumulate desired traits from novel
germplasm. Depending on the sequences and types of breeding decisions, this
type of physiology plus breeding simulation allows the identification of multiple
ideotypes that could be adapted to future climates.
References
Hammer GL, Cooper M, et al. (2006). Models for navigating biological complexity in breeding
improved crop plants. Trends in Plant Science 11(12): 587-593.
Howden SM, Soussana J-F, et al. (2007). Climate Change and Food Security Special Feature:
Adapting agriculture to climate change. PNAS 104(50): 19691-19696.
Porter JR, Semenov MA (2005). Crop responses to climatic variation. Philosophical Transactions of
the Royal Society B: Biological Sciences. 360(1463):2021 -2035.
Reynolds MP, Hays D, Chapman, SC Breeding for adaptation to heat and drought stress. In
Reynolds (ed) “Climate change and crop production”, CABI, pp 71-91.
Contact: scott.chapman@csiro.au
13
Crop improvement
Crop improvement strategies for genotypic
adaptation to climate change with special reference
to the abiotic stresses (salinity, drought,
submergence and high temperature) in rice
R.K. SINGH1, S.V.K JAGADISH2, R. W ASSMANN2
1
International Rice Research Institute, ESA Regional office, Tanzania
International Rice Research Institute, Los Banos, Philippines
2
Introduction
Worldwide environmental stress represent the most limiting factor for
agriculture productivity and abiotic stress tolerance belongs to most wanted list
of traits for the future crop plants (Hirt and Shinozaki 2004). Human induced
activities are making the world hot to hotter resulting into the global warming.
Increased CO2 concentration per se may not have the detrimental effects on
crop growth but the indirect effect of elevated CO2 concentration through rising
temperature in the atmosphere will have many adverse effects on plant in
addition to the sea level rise that affects low lying coastal areas and deltas of
the world. From 1993-2009, the mean rate of sea level rise has been reported
to 3.3± 0.4 mm/year indicating the increasing trend. Fourth assessment report
of IPCC projected the sea level rise by upto ~60 cm by 2100 in response to
ocean warming and glaciers melting under the business-as-usual A1FI
greenhouse gas emission scenario, while the projected estimates using other
models are 2-3 times higher than business-as-usual (Nicholls and Cazenave
2010). This will lead to increased coastal salinity and further yield reduction,
even in previously favourable areas (Wassmann et al. 2004) to imperil the food
security of millions of people, mostly the resource-poor. Africa coast line is
highly threatened due to sea level rise in conjunction with the low level of
development and rapid population growth in coastal areas. Increased
temperature will not only have the effect on coastal areas but also in arid and
semi arid regions of the world where good quality water is in scarce and
agriculture will have to compete with house hold and industrial use. More than
half (55%) of total ground water is naturally saline (Ghassemi et al. 1995).
Immediate impact of climate changes is envisaged in terms of changes in
precipitation that will seriously hamper the agricultural production than
temperature changes. Rice carries an exceptional range of adaptations to
existing and changing environments compared with other crop species due to
its ability to grow under very wide range of environments from humid tropics to
arid and semi-arid conditions and even to temperate zones. This broader
adaptation will make rice more amenable for manipulation to adjust to climate
changes as a consequence of global warming. However, to cope with these
changes, adjustments will be necessary both in breeding strategies to develop
14
Crop improvement
suitable and more robust varieties, as well as in management strategies to
cope with the new and changing conditions.
Plant response to increased CO2 concentration: Most of the plants react to the
altered CO2 concentration of the atmosphere in terms of stomatal conductance
that controls plant growth and transpiration. High response to stomatal
conductance is one of the important mechanisms conferring the salt and
drought tolerance in rice. The present CO2 concentration of 380ppm, projected
to double by the end of the century (IPCC 2007) could benefit rice crop by
increasing photosynthesis with consequent increase of biomass production.
Plant response to rising temperature: Rising temperature as consequence of
elevated CO2 concentration will result into improved water use efficiency
(WUE), improved plant water status and more rapid leaf production in the
vegetative growth phase provided there is non-limiting supply of the nutrients
(Grashoff et al. 1995). The increased temperature at the plant canopy level
lead to increased transpiration by changing the VPD at the leaf surface, and
also accelerated ageing of the foliage, and a shortening of the growing season
or grain-filling period which is very critical for the grain yield (Kenny et al, 1993).
Rising temperature will accelerate the crop development for most of the
cultivars that may lead to a reduced water use over the shortened growth
period, but also to a loss of potential yield and quality. It is likely that the
evaporative demand as determined by the VPD would increase by about 5 to
6% per degree warming (McKenney and Rosenberg 1993).
High CO2 concentration which shows many positive effects on plants cannot be
seen in isolation from high temperature and other changes in climate that CO2
may induce (Yeo 1999). Temperature is one of the most important climatic
factors affecting drought and salt tolerance. Ambient temperature beyond 33°C
increase the spikelet sterility (Matsui et al. 1997) while increase in one degree
reduce the yield by 0.6 t/ha (Sheehy 2005). Collectively, the disadvantages
largely out-weight the advantages for rice cultivation under predicted future
climatic changes.
Adaptive mechanism – Climate ready genotypes: Foreseeing the projections of
the high temperature regimes, the rice genotypes under abiotic stresses will
have to adapt in such a way that they do not suffer the yield penalties. It could
be possible if the rice genotypes or varieties are specifically tailored for multiple
stress tolerance by pyramiding of stresses in following combinations.
1. Enhanced degree of salinity tolerance: There are existing land races and
improved rice varieties but considering the future projections of climate change,
the salinity tolerance in the improved background need to be further enhanced.
This could be done by the pyramiding of the component mechanisms for
salinity tolerance like development of good excluder with better tissue
tolerance. A major QTL for salinity tolerance ‘Saltol’ has been reported and
successfully transferred to the adapted asian rice varieties to improve their
15
Crop improvement
tolerance to salinity, while work is in progress to transfer it in African rice
varieties.
2. Drought tolerance: It was concluded that in the absence of other potential
climate stresses, rice grown under future increases in atmospheric CO2
concentration may be better able to tolerate drought situations (Widodo et al.
2003). Although drought affects all stages of rice growth and development,
water stress during the flowering stage depresses grain formation much more
than drought at other reproductive stages (Boonjung and Fukai 1996). The
strong effects of drought on grain yield are largely due to the reduction of
spikelet fertility and panicle exsertion.
3. High temperature tolerance: Significant genotypic variation has been
reported for high temperature tolerance. The early morning flowering
advantage of O. glaberrima has been exploited in interspecific crosses
between O. glaberrima and O.sativa to advance peak flowering time of the day
by 1h towards early morning (Yoshida et al. 1981). N22, an aus variety, has
consistently shown tolerance to high temperature during anthesis (Prasad et al.
2006; Jagadish et al., 2008) and also known to be highly drought tolerant. QTL
mapping at grain filling stage revealed 3 major QTLs in rice conferring the
tolerance to heat on chromosomes 1, 4, and 7 with LOD scores of 8.16, 11.08,
and 12.86, respectively (Zhu et al. 2005).
4. Submergence Tolerance: A big affect major QTL ‘Sub1’ for submergence
tolerance has already been identified on chromosome 9 (Xu and Mackill 1996;
Xu et al. 2001) and successfully transferred through MAS into various megavariety backgrounds (Neeraja et al. 2007). This QTL confers tolerance to
complete submergence for about two weeks. Work at IRRI is in progress to
look for beyond 2 weeks tolerance. Sub1 varieties are in farmers field and
performing well with natural flooding.
5. Multiple tolerance: The desired combination for the climate ready
genotypes would be pooling the tolerance to various abiotic stresses like
salinity and high temperature tolerance; drought and salinity tolerance; salinity
and submergence into one background. With the sea-water rise, as the
projections are, saline water inundation in the coastal areas would be more
frequent than now. Therefore to cope-of with this twin stress problem – salinity
and submergence, rice plants need to have tolerance to both the stresses. As
MAS has already been tested and proven, therefore it is possible to develop
dual or multiple tolerant rice varieties as climate ready genotype for the future
demand. At IRRI, the work for the pyramiding of Saltol and Sub1 QTL through
MAS has been accomplished and genotypes with dual tolerance are already in
farmers field.
To have all the positive mechanisms in one variety, it is difficult but not
impossible. So ideal climate ready rice variety for the salt-stressed
environments should be heat, drought, salinity and submergence tolerant
beside the other wish list for the desired traits. Probably, this would be a reality
16
Crop improvement
in the times to come when robust markers on shelf for the desired traits are
available along with their easy introgression techniques.
Conclusion
The resilience of rice production systems in the climate change scenario has to
be increased in a two-pronged approach, (i) increasing tolerance to individual
stresses and at the same time, (ii) achieving multiple stress tolerance
(Wassmann et al. 2009). While increasing tolerance alone cannot be
considered as the ultimate solution to all threats posed by climate change, but
still germplasm development and improved agronomic practices should be a
center stage of climate change adaptation in agriculture. These approaches
have proven track records in achieving more resilience to climate variability and
extremes. This is particularly feasible in rice because of the enormous progress
made in discerning and understanding the traits associated with tolerance and
in developing DNA-based technologies for precise and speedy breeding of
better adapted varieties that may respond better to the improved management
practices to further boost and stabilize the productivity.
References
Boonjung, H., and Fukai, S. (1996). Effects of soil water deficit at different growth stages on rice
growth and yield under upland conditions .2. Phenology, biomass production and yield. Field
Crops Research 48, 47-55.
Ghassemi, F., Jakeman, A.J., Nix, H.A., 1995. Salinisation of land and water resources. CAB
International, Wallingford.
Grashoff, C., Dijkstra, P., Nonhebel, S., Schapendonk, A.H.C.M. and van de Geijn, S.C. 1995.
Effects of climate change on productivity of cereals and legumes; model evaluation of observed
year-to-year variability of the CO2 response. Global Change Biology 1 (6): 417-428.
Hirt, H. and K. Shinozaki. 2004. Plant Responses to abiotic stress. Springer-Verlag Berlin
Heidelberg. 300pp.
IPCC (Intergovernmental Panel on Climate Change) (2007) Climate Change 2007: The Physical
Science Basis (Summary for Policymakers). IPPC Secretariat, WMO, Geneva, Switzerland pp
21
Jagadish SVK, Craufurd PQ, Wheeler TR (2008) Phenotyping parents of mapping populations of
rice (Oryza sativa L.) for heat tolerance during anthesis. Crop Science, 48:1140–1146.
Kenny, G.J., Harrison, P.A., Olesen, J.E. and Parry, M.J. 1993. The effects of climate change on
land suitability of grain maize, winter wheat and cauliflower in Europe. Eur. J. of Agronomy 2:
325-338.
Matsui, T, O.S. Namuco, L.H. Ziska, and T. Horie. 1997. Effects of high temperature and CO2
concentration on spikelet sterility in indica rice. Field Crops Research 51: 213-219.
McKenney, M.S. and Rosenberg, N.J. 1993. Sensitivity of some potential evapotranspiration
estimation methods to climate change. Agric. For. Meteorol. 64:81-110.
Neeraja CN, Maghirang-Rodriguez R, Pamplona A, Heuer S, Collard BCY, Septiningsih EM,
Vergara G, Sanchez D, Xu K, Ismail AM, Mackill DJ (2007) A marker-assisted backcross
approach for developing submergence-tolerant rice cultivars. Theor Appl Genet.
doi:10.1007/s00122-007-0607-0
Nicholls RJ, Cazenave A. 2010. Sea-Level Rise and Its Impact on Coastal Zones. Science 328:
1517-20.
17
Crop improvement
Prasad, P. V. V., Boote, K. J., Allen, L. H., Sheehy, J. E., and Thomas, J. M. G. (2006). Species,
ecotype and cultivar differences in spikelet fertility and harvest index of rice in response to high
temperature stress. Field Crops Research 95, 398-411.
Sheehy, J.E., P.L. Mitchell, and A.B. Ferrer. 2006. Decline in rice grain yields with temperature:
Models and correlations can give different estimates. Field Crop Res. 98: 151-156
Wassmann, R., N.X. Hien, C.T. Hoanh, T.P. Tuong. 2004. Sea Level Rise affecting Vietnamese
Mekong Delta: Water Elevation in Flood Season and Implications for Rice Production. Climatic
Change 66 (1):89-107
Wassmann, R, Jagadish SVK, Heuer S, Ismail A, Redoña E, Serraj R, Singh RK, Howell G, Pathak
H, Sumfleth K. 2009. Climate Change Affecting Rice Production: The Physiological and
Agronomic Basis for Possible Adaptation Strategies. Advances in Agronomy. 101: 59-102.
Widodo, W., Vu, J. C. V., Boote, K. J., Baker, J. T., and Allen, L. H. (2003). Elevated growth CO2
delays drought stress and accelerates recovery of rice leaf photosynthesis. Environmental and
Experimental Botany 49, 259-272.
Xu K and Mackill DJ. 1996. A major locus for submergence tolerance mapped on rice chromosome
9. Molecular Breeding Vol 2: 219-224.
Xu, K.; X. Xu; P. C. Ronald and D. J. Mackill. 2000. A high-resolution linkage map of the vicinity of
the rice submergence tolerance locus Sub1. Mol. Gen. Genet. 263: 681-689.
Yeo, A. 1999. Predicting the interaction between the effects of salinity and climate change on crop
plants. Scientia Horticulturae. 78: 159-174.
Yoshida, S., Satake, T., and Mackill, D. (1981). High temperature Stress. IRRI Research Papers
67, 1-15.
Zhu, C., Xiao,Y., Wang,C.,Jiang,L.,Zhai,H. and Wan,J. (2005). Mapping QTL for heat-tolerance at
grain filling stage in rice. Rice sci 12, 33-38.
Contact: r.k.singh@cgiar.org
18
Crop improvement
Adapting lowland rice cultivation to climate change
– thermal stress tolerance breeding in the Sahel
region of West Africa
BABOUCARR MANNEH1, ABDOULAYE SOW 1, PAUL KIEPE2, MICHAEL
DINGKUHN3
1
AfricaRice, Saint-Louis, Senegal
AfricaRice, Cotounou, Benin
3
CIRAD, BIOS Department, Montpellier, France
2
The Sahel region of West Africa is characterized by extreme diurnal and
seasonal temperature variation subjecting the rice crop to thermal stress at
different growth stages. The Africa Rice Center in collaboration with partners is
aims to identify rice genotypes and associated traits for use in breeding
varieties adapted to the Sahel climate. In one set of field trials established at
Ndiaye, Senegal, 244 diverse rice genotypes, including four checks, were sown
in February, March, April and July subjecting the rice plants to cold and heat
stress at different growth stages. Daily minimum temperatures fell below 20 °C
in the months of February and March whilst maximum temperatures regularly
rose above 40 °C in April, May and June. The rice crop is thus subjected to
cold stress in February and March and to heat stress in April to June. Across
the planting dates, total biomass production was highest on average for the
February planting date (293.8g/plant) followed by the April planting date
(281.0g/plant) and lowest for the July planting date (215.4g/plant). However,
spikelet sterility was highest for the April planting date on average relative to
other planting dates and lowest for the July planting date. On average plantings
in July were earliest (100 days from sowing to maturity) relative to other
planting dates whilst plantings in February which corresponded to the sowing
date for the dry season crop had the longest crop durations (137 days from
sowing to maturity). With regards to crop duration across the planting dates,
Chromrong a cold tolerant check from Nepal had the shortest duration across
all dates whilst N22 the international heat tolerant check had the longest
duration. IR64 an international irrigated lowland check variety and Sahel 108 a
local check variety had crop durations generally intermediate between these
two checks. Large genotypic variations detected in these traits will be exploited
in selecting parents to develop new varieties better adapted to the seasonal
Sahelian climate.
Keywords: Genotype, adaptation Sahel region, cold stress, heat stress,
biomass, spikelet sterility
Contact: B.Manneh@CGIAR.ORG
19
Crop improvement
Temperature constraint in Upland rice improvement
in the High Plateau of Madagascar
RAMANANTSOANIRINA ALAIN1, LOUIS MARIE RABOIN2, JULIE DUSSERE2,
SUCHIT SHRESTHA3, HOLGER BRUECK3, FOLKARD ASCH3
1
FOFIFA, URP-SCRID, ANTSIRABE, MADAGASCAR
CIRAD,URP-SCRiD, ANTSIRABE, MADAGASCAR
3
UNIVERSITY OF HOHENHEIM, GERMANY
2
In Madagascar, rice is cultivated on 1.3Mha of which 29% are upland rice,
growing from the coastal area up to the higher altitude. In the mid-1980s,
CIRAD and FOFIFA launched a research program for the highlands with the
aim of pushing forward the frontier of upland rice growing areas in high
elevation areas. Today, upland rice is a part of the Madagascar Highland?s
landscape and creates new breeding challenges. Low temperatures slow down
rice growth at almost all stages: panicle initiation is delayed and cold conditions
during the reproductive stage may induce high sterility rate. Thermal
environment also is known to affect the speed of vegetative development of the
crop, thus the crop duration itself. Climate change is assumed to result in a rise
of mean Temperatures of 2-5 degrees depending on the simulation scenario.
Thus rice cropping in higher altitudes may become more favorable as long as
precipitation is not a limiting factor. Fields experiments were conducted in
three locations along an altitudinal gradient, by using ten contrasting upland
genotypes with 5 monthly staggered planting dates. Physiological and
Phenological responses, grain yield and yield components, harvest index and
sterility were observed in view of detecting genotypic differences across
changing environments. In all ten varieties, crop duration was longer in higher
altitude as compared to lower altitude while Harvest index was found to be
higher in lower altitude. Low temperature effect was revealed by the rate of
sterility. The percentage of filled spikelet was linked to the minimal
Temperature between booting and heading stage and a linear relationship was
used to detect the threshold Temperature leading to sterility for all varieties
studied. Cold tolerant varieties adapted to high altitude showed higher yield in
high altitude when sown in the recommended sowing date and performed well
in both favorable and unfavorable environment. These varieties can respond
favorably in high altitude upland rice cropping with changing climate and used
as upland rice ideotype. Adaptability to low temperature was studied and
results can be used for modeling to foresee climatic change scenarios.
Keywords: upland rice, high altitude, breeding, climate change, adaptation
Contact : ntsoanirina@moov.mg
20
Crop improvement
Mining Genes for Late-season Drought Tolerance in
Maize
MITCHELL TUINSTRA1, MIKE POPELKA1, KARTIK KROTHAPALLI1, GURI
JOHAL2, MIKE MICKELBART3,SARA LARSSON4, EDWARD BUCKLER5
1
Department of Agronomy, Purdue University, West Lafayette, IN 47906
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47906;
3
Department of Horticulture, Purdue University, West Lafayette, IN 47906;
4
Dept. of Plant Breeding and Genetics, Cornell University, Ithaca NY 14850
5
USDA–ARS and Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York
14853
2
Keywords: Zea mays (L.), drought, germplasm, QTL mapping, plant breeding
Introduction
Efforts to develop crops and management strategies that enhance food
production in stressful climates and growth conditions have never been more
important. Yield gains of crops in favorable production environments have been
steady and consistent from year to year, but future gains may not be sufficient
to support the increase in population predicted by 2050 (Schmidhuber and
Tubiello 2007). These challenges may be exacerbated by forecasts of more
extreme temperature and drought conditions associated with global climate
change.
Plant responses to drought stress vary depending on the severity of conditions
and stage of plant development (Lee and Tollenaar 2007). Many studies have
been conducted focusing on drought tolerance during the seedling or early
vegetative stages; however, adult plant tolerance traits such as shortened
anthesis-silk interval, increased transpiration efficiency, osmotic adjustment,
and non-senescence generally have a much more profound impact on crop
productivity under drought stress conditions (Richards, 2005). These traits
improve crop productivity by increasing water-use efficiency or partitioning of
biomass to grain.
Tolerance to drought during the grain maturation stage is correlated with
enhanced crop productivity, grain quality, and lodging resistance in many
crops. Crops that exhibit this form of tolerance often delay senescence under
stress conditions. Green leaf retention is commonly referred to as visual
staygreen, whereas functional staygreen is defined by maintenance of
photosynthetically active tissue (Thomas and Howarth 2000). The staygreen
trait has proven to be effective in adapting crops for production in water-limited
environments (Thomas and Howarth 2000; Borrell et al. 2000; Hortensteiner
2009; Chen et al. 2010).
Efforts are being made to develop maize germplasm with improved staygreen
traits, but more research is needed to characterize sources of germplasm that
contribute to staygreen under drought, identify the genes controlling functional
21
Crop improvement
staygreen, and develop a better understanding of the physiological and
agronomic impacts of staygreen in hybrid cultivar development.
Materials and Methods
Field Trials: Field trials to evaluate the Purdue maize germplasm collections
and testcrosses for differences in chlorophyll content and chlorophyll
fluorescence during grain maturation and for grain yield were conducted in
West Lafayette, IN in 2008 and 2009 and Garden City, KS in 2010. Advanced
Backcross QTL mapping populations with Mo20W were evaluated for
differences in chlorophyll content and chlorophyll fluorescence during grain
maturation in Garden City, KS in 2010. Testcross hybrids of lines from the Nest
Association Mapping (NAM) populations of maize were evaluated for
differences in chlorophyll content at physiological maturity in West Lafayette IN,
Slater IA, Columbia MO, and Jackson Springs NC in 2010.
QTL Mapping: QTL mapping studies are being conducted to identify loci
associated with expression of staygreen in maize. In the first experiment,
Mo20W was used to produce 760 BC2-progeny in backcrosses to B73 and
Mo17. These populations were evaluated in field trials for differences in
staygreen based on chlorophyll content and chlorophyll fluorescence under
severe late-season drought stress in Garden City, KS. In the second
experiment, QTL for staygreen were identified in testcross hybrids of the
nested association mapping (NAM) population of maize produced from crosses
with PHZ51. These hybrids were evaluated in multi-location field trials for
differences in staygreen based on leaf chlorophyll content at 670 growing
degree days after silking.
Gene Cloning: Gene tagging studies with the Mutator(Mu) transposable
element were initiated for two independent mutations, pre-1 and pre-fl940, that
produceplants with premature senescence or loss of staygreen. These mutants
were crossed with B73 to produce F2 and BC1F2 mapping populations for
cloning by selective amplification of inserted flanking fragments (SAIFF)
methods of Muszynski et al. (2006).
Results and Discussion
Analyses of inbred lines with contrasting staygreen characteristics and their
testcross hybrids demonstrated significant differences among entries in the
timing and pattern of senescence. Some inbred lines such as B14A expressed
excellent staygreen per se but produced senescent hybrids; while other lines
such as Mo20W had good expression of staygreen per se and in hybrid
combinations (Figure 1).
Field experiments evaluating the QTL mapping populations derived from
Mo20W indicated significant variation for staygreen under severe late-season
stress (Figure 2). Transgressive segregation was detected with a substantial
number of progeny showing a high degree of stress tolerance. Ongoing QTL
mapping experiments are focused on detailed comparisons of the phenotypic
22
Crop improvement
extremes of each population. Selected staygreen progeny from each
population represent an excellent source of QTL for functional staygreen
derived from Mo20W.
Phenotypic analyses of testcross hybrids of the NAM populations demonstrated
significant genetic variation for green leaf retention. Preliminary QTL mapping
results demonstrated numerous QTL for staygreen. Some of these loci appear
to be coincident with QTL for flowering time; however, several promising
candidates were identified. These results suggest that the NAM founder lines
may represent a useful source of QTL alleles for staygreen for use in crop
improvement.
Figure 1. Variations in chlorophyll content and Fv/Fm of B73, Mo17, and Mo20W
measured during grain development under water limited conditions.
23
Crop improvement
50
B73
Mo20W
Frequency
40
30
20
10
0
10
15
20
25
30
Leaf Greenness
35
40
Figure 2.Frequency distribution of backcross lines (BC2) derived from B73 x
Mo20W for differences in staygreen under severe late season stress at 28 days
after silking.
References
Borrell A.K., G.L. Hammer, R.G.Henzell. 2000. Does maintaining green leaf area in sorghum
improve yield under drought? II. Dry matter production and yield. Crop Science 40:1037-1048.
Chen J., Y. Liang, X. Hu, X. Wang, F. Tan, H. Zhang, Z. Ren and P. Luo. 2010. Physiological
characterization of ‘stay green’ wheat cultivars during the grain filling stage under field growing
conditions. Acta Physiologiae Plantarum 32: 875-882.
Harris K., P.K. Subudhi, A. Borrell, D. Jordan, D. Rosenow, H. Nguyen, P. Klein, R. Klein and J.
Mullet. 2007. Sorghum stay-green QTL individually reduce post-flowering drought-induced leaf
senescence. Journal of Experimental Botany 58: 327–338
Hortensteiner S. 2009. Stay-green regulates chlorophyll and chlorophyll-binding protein
degradation during senescence. Trends in Plant Science 14: 155-162
Lee E.A. and M. Tollenaar. 2007. Physiological Basis of Successful Breeding Strategies for Maize
Grain Yield. Crop Science 47: S-202-S-215.
Richards R.A. 2005. Physiological traits used in the breeding of new cultivars for water-scarce
environments. Agricultural Water Management 80: 197-211
SchmidhuberJ., and F.N. Tubiello. 2007. Climate Change and Food Security Special Feature
Global food security under climate change. PNAS 104:19703-19708.
Spano G., N. Di Fonzo, C. Perrotta, C. Platani, G. Ronga, D.W. Lawlor, J. A. Napier and P.R.
Shewry. 2003. Physiological characterization of ‘stay green’ mutants in durum wheat. 54: 14151420.
Thomas H. and C.J. Howarth. 2000. Five ways to stay green. Journal of Experimental Botany 51:
329-337.
24
Crop improvement
Crop Improvement Strategies for Genotypic
Adaptation to Climate Change
B.I.G. HAUSSMANN1, H.K. PARZIES 2
1
2
ICRISAT, Niamey, Niger, Contact: b.ig.haussmann@icrisatne.ne
Univ. of Hohenheim, Inst. of Plant Breeding, Seed Sci. & Population Genetics, Stuttgart, Germany
Keywords: Heterozygosity, heterogeneity, phenotypic plasticity, direct versus
indirect selection, IGNRM
Introduction
Crop improvement generally aims at increasing the adaptation, i.e., yield
performance and stability, of crops in a target region. Specific quality traits
need to be addressed simultaneously with the performance traits, to assure
final adoption by end-users. Major strategic challenges for crop improvement in
the light of climate change lie in:
• Ability to foresee the effects of future climate change;
• Supporting conservation and characterization of plant genetic resources;
• Improving adaptation to unpredictable climate variability;
• Improving tolerance to higher temperatures, drought stress and flooding;
• Integrated genetic and natural resource management; and
• Farmer-participatory breeding.
Each of these strategic issues will be shortly discussed in the following.
Ability to foresee the effects of future climate change
The development and validation of new crop cultivars requires six to ten years.
Therefore, breeders must be able to foresee the expected climate-related
changes in their target region. To address climate change in a timely manner,
breeders should cooperate with climate researchers and plant growth
modelers. Based on existing climate change models, one strategy can be to
identify “analogue locations” that have today the climatic characteristics that
are expected tomorrow in a chosen target production zone (Cooper 2010, pers.
com.). Burke et al. (2009) have shown that, due to altitudinal effects on air
temperatures, several countries in Eastern and Southern Africa have good
within-country potential to use analogue locations to study the effect of
increasing temperatures on crops. Little is known about the effects of climate
change on pest, parasite and plant disease appearance. But such information
will be essential to design appropriate resistance breeding programs in view of
climate change. Identification of analogue locations may help in estimating both
biotic and abiotic stress frequencies under climate change.
Supporting conservation and characterization of plant genetic resources
Genetic variation and availability of sources of resistance to specific production
constraints is the capital of each breeder. Climate change bears the risk of
25
Crop improvement
irreversible loss of valuable genetic resources. Therefore breeders should
support genebanks to assure that current germplasm collections are as
complete as possible. Furthermore, germplasm (core) collections should be
characterized to identify sources of resistance to climate-change-related
stresses.
Improving adaptation to climate variability
A better understanding of the mechanisms of coping with current climate
variability will be a prerequisite for adaptation to future climate change (Cooper
et al. 2006). Yield stability in unpredictably variable environments can be
achieved through i) phenotypic plasticity (“individual buffering”) and ii) diversity
for adaptation traits in a genetically heterogeneous variety or plant stand
(“populational buffering”, Allard and Bradshaw 1964). Populational buffering
results in a more static stability – the plant population producing a stable
minimum yield. Response to favorable years (dynamic stability concept) is
better achieved via phenotypic plasticity. The target farmers’ risk aversion
should be determined to decide on the appropriate yield stability concept, static
versus dynamic. For vulnerable small-holder farmers, a stable minimum yield
may often be more important than high cultivar to response to better years.
An example for phenotypic plasticity is photoperiod-sensitive flowering of West
African guinea-race sorghum [Sorghum bicolor (L.) Moench] and pearl millet
(Pennisetum glaucum L. Br.) landraces. Photoperiod-sensitivity assures
flowering at the (more predictable) end of the rainy season, independent of the
highly variable planting dates which are due to the scattered beginning of the
rainy season. This optimizes the use of available rains. Photoperiod sensitivity
has been removed from “elite” germplasm during the green revolution, but may
be needed for adaptation to climate variability and change, especially when
dealing with vulnerable farmers. High tillering potential is another example for
individual buffering via phenotypic plasticity. Van Oosterom et al. (2005)
showed that high tillering is a major adaptation trait enhancing yielding stability
of pearl millet in harsh and variable arid desert margins of Rajasthan (India).
Individual buffering may be enhanced through heterozygosity (two different
alleles at a gene locus) or alloploidy (different alleles available from the
different genomes of an alloploid species, e.g., wheat). Such intra-genotypic
diversity can enlarge the adaptation range of a genotype – and therefore its
adaptation to climate variability. The degree of heterozygosity can be
influenced by breeders through i) choice of variety type - both hybrids and
open-pollinated cultivars profit from heterozygosity; ii) through exploitation of
heterotic groups in both population and hybrid breeding to maximize the
heterozygosity; and iii) through recurrent selection for increased outcrossing
rate of predominantly autogamous species (e.g., sorghum).
Populational buffering requires genetic variation within a variety for adaptation
traits. It may not be by chance that pearl millet landraces in the African Sahel
show enormous intra-varietal variability for flowering time - a characteristic that
26
Crop improvement
assures that not all panicles in the plant stand will be affected by a drought
spell in their most sensitive stage of flowering (Haussmann et al. 2007). This
may in fact be a major adaptation mechanism to the high inter-annual climate
variability present in the Sahel. A concomitant question plant breeders are
facing is how much intra-varietal heterogeneity is desirable, or necessary, in
order to obtain improved, stable varieties that out-yield local cultivars under
extreme and variable growing conditions.
Genetically heterogeneous cultivar types that can profit from populational
buffering include multi-line (autogamous species), open-pollinated population
and synthetic varieties, 3-way, 4-way and top cross hybrids. In contrast, line
and single-cross hybrid cultivars are genetically uniform and cannot perform
populational buffering. So when choosing the variety type, the breeder can
influence the capacity for populational buffering and therefore yield stability in
variable climates. Alternatively, breeders may recommend to farmers to grow a
diversity of cultivars that all together will assure populational buffering. If
seasonal predictions were precise, a tactical choice of best adapted cultivars
could maximize production in each cropping season.
Improving tolerance to higher temperatures, drought stress and flooding
Predictions of temperature increases due to climate change appear to be much
more robust than those of associated changes in rainfall patterns. Recent
analyses of long-term daily climate data confirm that such temperature
increases are already occurring (Van de Steeg et al. 2009). Furthermore,
unpredictable drought and flooding after excess rainfall remain important stress
factors in variable and changing climates. Crop improvement strategies
targeting abiotic stress resistance can be divided into direct selection for
performance in the target stress environment and indirect selection methods for
e.g., specific morphological, phenological or physiological characteristics
(physiology-aided breeding) – either under stress or under non-stress
conditions. It must be underlined that indirect selection can only be effective if
there is a positive genetic correlation between the indirect selection trait and
performance under stress. Direct farmer-participatory mass selection in a
random-mating sorghum population grown in a flooded field was shown to be
efficient in enhancing flooding tolerance (Rattunde et al. 2009).
With the enhanced understanding of gene functions in relation to stress
tolerance, and with DNA marker information becoming less and less costly,
genomic selection is also a promising strategy to improve abiotic and biotic
stress resistance (Jannink et al. 2010). Genomic selection uses high-density
DNA marker information to predict performance. This approach seems much
more suitable for improvement of quantitative traits determined by many genes
with small effects than classical marker-assisted selection targeting individual
quantitative gene loci.
27
Crop improvement
Integrated genetic and natural resource management
Crop improvement alone cannot produce miracles. The development of new
improved and climate-proof cultivars must go hand in hand with sustainable soil
fertility management and water conservation techniques. Integrated genetic
and natural resource management (IGNRM) means selecting varieties that are
most responsive to specific soil fertility and water conservation techniques,
based on analysis of genotype × crop management × location interactions. It
may also include developing genotypes suitable for mixed cropping. A sound
IGNRM strategy requires cooperation between plant breeders and systems
agronomists.
Farmer-participatory breeding
Finally, to ensure to develop new varieties with enhanced adaptation to climate
change that will be relevant and adoptable to farmers, it is important to
associate farmers in the different stages of a breeding program, from priority
setting to identification of suitable breeding materials, to variety development,
validation and dissemination. Using such an approach will shorten the time
between variety finalization and adoption by farmers (Christinck et al. 2005).
References
Allard RW, Bradshaw AD. 1964. Implications of genotype-environmental interactions in applied
plant breeding. Crop Sci. 4: 503-507.
Burke, M.B., Lobell, D.B., Guarino, L. 2009. Shifts in african crop climates by 2050, and the
implications for crop improvement and genetic resources conservation. Global Environmental
Change, 19(3), 317-325.
Cooper P, Dimes J, Rao KPC, Shapiro B, Shiferaw B, Twomlow S. 2006. Coping better with
current climatic variability in the rain-fed farming systems of sub-Saharan Africa: A dress
rehearsal for adaptation to future climate change? ICRISAT GTAE Report No. 27. ICRISAT,
Patancheru PO, India.
Haussmann BIG, Boureima SS, Kassari IA, Moumouni KH, Boubacar A. 2007. Two mechanisms of
adaptation to climate variability in West African pearl millet landraces – a preliminary
assessment. E-Journal of SAT Research. Vol. 3(1). Sorghum, millets and other cereals.
http://ejournal.icrisat.org/. 3pp.
Jannink, J., Lorenz, A.J., Iwata, H. (2010). Genomic selection in plant breeding: From theory to
practice. Briefings in Functional Genomics and Proteomics, 9(2), 166-177.
Rattunde HFW, vom Brocke K, Weltzien E, Haussmann BIG. 2009. Developing open-pollinated
varieties using recurrent selection methods. Pages 259 – 273 In: Participatory Plant Breeding
(S Ceccarelli, EP Guimarães, E Weltzien and PG Rajendran, Eds). FAO, Rome, Italy.
Van de Steeg J, Herrero M, Kinyagi J, Thornton PK, Rao KPC, Stern R, Cooper P. 2009. “Climateinduced risk and production uncertainty”, pp36-53 in ‘The influence of climate variability and
climate change on the agricultural sector in East and central Africa. Res. Report 22, ILRI.
Van Oosterom EJ, Weltzien E, Yadav OP, Bidinger FR. 2005. Grain yield components of pearl
millet under optimum conditions can be used to identify germplasm with adaptation to arid
zones. Field Crops Research 96: 407-421.
Christinck A, Weltzien E, Hoffmann V, 2005. Setting breeding objectives and developing seed
systems with farmers: A handbook for practical use in participatory plant breeding projects.
ISBN 3-8236-1449-5. Margraf Publishers, Germany.
28
Crop improvement
A novel methodology for ex ante assessment of
climate change adaptation strategies: examples
from East Africa
JETSE STOORVOGEL3, LIEVEN CLAESSEN1, JOHN ANTLE2, PHILIP
THORNTON4, MARIO HERRERO4
1
International Potato Center, Nairobi, Kenya
Oregon State University, Corvallis, USA
3
Wageningen University, Wageningen, the Netherlands
4
International Livestock Research Institute, Nairobi, Kenya
2
Sub-Saharan Africa (SSA) is predicted to experience considerable negative
impacts of climate change. The IPCC Fourth Assessment Report emphasizes
that adaptation strategies are essential. Addressing adaptation in the context of
small-scale, semi-subsistence agriculture raises special challenges. An
important constraint is that data demands are high, because site-specific biophysical and economic data are required. The development of relatively simple
methods for ex ante evaluation of adaptation at the household and system
levels is therefore needed. We test a new approach to ex ante impact
assessment that produces site-specific results that can also be aggregated for
regional analysis. The methodology uses the kinds of data that are more often
available in resource-poor countries. The stochastic approach integrates socioeconomic and bio-physical data on farmers’ land allocation, production, input
and output use. Characteristics of the agricultural system regarding resources
and productivity are analyzed and compared for both current and projected
climate. Possible adaptation strategies are then assessed for their capability to
reduce or offset the adverse effects of climate change. In this paper we apply
the methodology to two study areas in Kenya. After characterizing the current
systems with actual climate data, the effects of a perturbed climate are
analyzed and a variety of adaptation strategies tested. Despite the limitations,
the new approach offers a flexible framework for evaluating adaptation
strategies using scarce data of resource-poor countries in SSA and other parts
of the world. It allows a rapid integrative analysis for timely advice to
policymakers and for exploration of technology and policy options.
Keywords: adaptation, climate change, sweet potato, East Africa, impact
assessment
Contact: l.claessens@cgiar.org
29
Traits for ideotypes
Traits for ideotypes to adapt African crops to
climate change
PETER CRAUFURD1, PETER COOPER2, KPC RAO3, ROGER STERN2,
VINCENT VADEZ1, JILL CAIRNS4, VN NAGESWARA RAO1
1
ICRISAT, Patancheru, AP 502324, India
University of Reading, Reading, UK
3
ICRISAT, Nairobi, Kenya
4
CIMMYT, Mexico
2
Introduction
Climate variability – the norm for most farmers in sub-humid and semi-arid
Africa- and anthropogenic climate change are important constraints and
drivers, respectively, of agricultural research for development (R4D) in subSaharan Africa (SSA). Climate variability has always been a major constraint
and in the short to medium term it is variability rather than change in the mean
that is the major research and crop improvement issue (Cooper et al. 2009),
as breeding and technology cycles typically operate over a 10 to 20 year
timeframe.
There are many climate change impact studies for SSA all of which suggest
that temperature rather than rainfall will become more limiting in future
(Schlenker & Lobell 2009, Burke et al. 2009). Southern Africa is likely to be the
region most affected by climate change (IPCC 2007). For example, Nelson et
al. (2010) report that maize and millet yields in SSA are predicted to decline by
7.1 to 9.6% and 6.9 to 7.6%, respectively across SSA. Schlenker & Lobell
(2009) report median declines of 22, 17, 17, 18 and 8% for maize, sorghum,
millet, groundnut and cassava respectively. Most of these declines are
associated with shorter crop durations and hence time to accumulate biomass;
conversely, where yields are predicted to increase – for example in some
highland regions- this is attributed to more favourable growing temperatures
(Thornton et al. 2009; Cooper et al. 2009). However, many of these studies do
not take into account temperatures above critical thresholds, typically around
33°C, at the most sensitive stage of development, namely around flowering
(microsporogenesis through fertilization). Although temperature is likely to have
a larger impact on productivity than rainfall, water deficit and drought stress
(water deficit and temperature stress) will still be locally important (Cooper et
al. 2009).
Adaptation to variable climates, and the occurrence of temperature and water
stress, will still be largely determined by phenological or developmental
responses, i.e. by selecting varieties whose life-cycle matches the duration of
the growing season and wherein stress at the most sensitive stage of
development – flowering – is avoided. This paper will focus on phenology,
looking first at predicted changes in season length and the start/end of the
season, and then at mechanisms that adapt varieties to this situation.
30
Traits for ideotypes
Secondly, we will look specifically at genotypic variation in heat tolerance at
flowering and its potential benefits. Thirdly, we will look at other traits that
contribute to adaptation to climate change, including traits associated with
transpiration efficiency. Lastly, and briefly, we also highlight other areas
requiring more research, such as pest and disease dynamics under climate
change.
Materials & Methods
The results presented in the paper are from on-going work at ICRISAT and
CIMMYT, some published and some in press (Cooper et al. 2009). The earlier
works describe the variation in season length and dry spells in long runs of
observed daily data at selected locations. We also conducted a series of
simulations building on work already published by Cooper and his co-workers.
These simulations used 50 years or so of daily data from selected locations in
Africa that represent different climates (Makindu and/or Katumani, Kenya;
Bulawayo in Zimbabwe; and Bamako in Mali) and the crop model APSIM.
Using maize as an exemplar, we examined the effect of varying response to
temperature and the optimum temperature, photoperiod sensitivity and the
minimum duration to flowering (vegetative phase duration). These are the
major factors determining phenology and for which there is genotypic variation.
Following Cooper et al. (2009), we also ran a sensitivity analysis with increases in temperature and changes in rainfall to study impacts on phenology.
We also studied the occurrence of high temperature events and their impacts.
Results and discussion
Changes in climate, both average and variability, will influence the distribution
of agro-ecological zones or climates, season length, the start and end of the
season (rains) as well as have direct effects on rates of development and key
yield forming processes.
Shift in agro-ecological zones
The distribution and position of agroecological zones will change in future
climates, presenting both opportunities and threats. SAT areas, for example,
with a 2°C change in average temperature and a 10% decline in rainfall relative
2
to the baseline will increase by approximately 1700 km globally (Fig. 1); SAT
areas are lost at the drier extremes to arid climates and gained at the wetter
extremes from dry sub-humid climates. Shifting the position of these zones has
obvious implications for crop improvement and agriculture generally, as cultivar
adaptation domains may well change where zones are now in more southerly
or northerly latitudes and hence experience different photoperiods.
Length of growing period (LGP)
The duration of the season, usually measured as LGP that takes into account
available soil moisture, is extremely variable today and indeed in many
locations the variability experienced in the last 50 years more than covers what
is expected in future. For example, over the last 50 years at Makindu in Kenya
31
Traits for ideotypes
the median LGP is 110 days. However, the LGP has varied from as little as 25
d to >175 d in that time (Fig. 2).
Figure 1. The projected change in the global extent of the SAT with a 2°C increase
in average temperature and a 10% reduction in rainfall.
29 Dec
29 Nov
30 Oct
1960
1970
1980
1990
2000
Figure 2. The date of onset of the Short rainy Season at Makindu, Kenya under
two scenarios: (A) the date by which 15mm fell in a 3-day period (green line) and
(B) Scenario ‘A’, but with the caveat that it should not be followed by a 12-day dry
spell (blue line).
Start and end of the season (rains)
In calendar time, the variation in LGP above equates to planting dates from
mid-October through to the end of December. Such variability in planting date
has in many crop species necessitated the use of photoperiod sensitivity as a
mechanism to ensure stable yields, notably in West Africa (e.g. Curtis 1968).
32
Traits for ideotypes
Photoperiod sensitivity basically allows for the length of the vegetative phase to
vary with planting date, such that flowering occurs around the same time each
season. In West Africa this mechanism works particularly well as the end of the
season is far more predictable (and less variable) than the start. The timing of
flowering is also critical in relation to pests and many diseases.
Temperature, photoperiod and minimum time to flower
It is well known that plants exhibit an optimum temperature response, wherein
rates of development are fastest (i.e. flowering occurs soonest) at the optimum
temperature, and most importantly in the context of climate change, rates slow
(i.e. flowering is delayed) when temperature exceeds the optimum. Optimum
temperatures typically vary from 20 to 24°C in temperature crops such as
wheat to >30°C in tropical crops such as sorghum or millet. There is also
genetic variation in the optimum temperature (e.g. lowland and highland
tropical and temperate maize). Selecting for variation in optimum temperature
is therefore one mechanism that can be used to vary crop duration. However,
as most average seasonal temperatures are below the optimum, warmer
temperatures generally result in shorter durations, which maybe undesirable.
For these environments, either a long vegetative phase or minimum time to
flower (exemplified by the BVP in rice, but also long-juvenile trait in soybean)
and/or photoperiod sensitivity may be required.
High temperature stress at flowering
High temperature at flowering, above about 33°C in crop species such as rice,
sorghum and groundnut, can reduce seed-set and hence yields dramatically,
and maybe a significant constraint in future. While high temperatures of these
magnitudes do not necessarily occur frequently, where water deficit occurs
high temperature is often an exacerbating factor due to warmer tissues
temperature as a result of reduced transpiration. There is genetic variation in
heat tolerance in a number of crops, including sorghum, rice, cowpea and
groundnut, and crops such as millet are said to be very heat tolerant also.
Maize however is very sensitive to high stress at flowering and as this crop
gains in popularity over sorghum, more adverse effects are to be expected
(Thornton et al. 2009).
Other traits
Just has it is now sensible to use analogue climates to examine adaptation,
similarly it is sensible to look at traits possessed by crops adapted to harsh
environments, such as millet or cowpea. In addition to variation in phenology
and heat tolerance for seed-set at flowering, these crops exhibit considerable
developmental plasticity through indeterminancy (tillering, branching,
flowering), and this is a key lesson.
Other traits of interest include those that limit transpiration and essentially
conserve water for later in the season, and so called stay-green traits that
contribute to seed-filling. There are isogenic lines of millet that consistently
33
Traits for ideotypes
exhibit lower transpiration in response to demand (VPD), that may be useful.
Likewise, stay-green lines are beneficial in many environments.
References
Burke, M., D. Lobell, et al. (2009). "shifts in African crop climates by 2050, and the implications for
crop improvement and genetic resources conservation." Global Environmental Change.
Cooper, P., K. Rao, et al. (2009). "Farming with current and future climate risk: Advancing a
'Hypothesis of Hope' for rainfed agriculture in the semi-arid tropics " SAT ejournal published by
ICRISAT 7: 1-19.
Curtis, D. J. (1968). "The relation between yield and date of heading of Nigerian sorghums."
Experimental Agriculture 4: 93-101.
IPCC. (2007). Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability, IPCC:
23.
Nelson, G., M. Rosegrant, et al. (2009). Climate Change ; Impact on Agriculture and Costs of
AdaptationImpact on Agriculture and Costs of Adaptation. International Food Policy Research
Institute: 1 of 19.
Schlenker, W. and D. Lobell (2010). "Robust negative impacts of climate change on African
agriculture " Environmental Research Letters (Open access journal for environmental
research): 1 of 10.
Thornton, P., P. Jones, et al. (2009). "Spatial variation of crop yield response to climate change in
East Africa." Global Environmental Change.
34
Traits for ideotypes
Marker assisted recurrent selection for increased
outcrossing rates in caudatum-race sorghum from
Sudan
HEIKO K. PARZIES1, ABUBAKER A. ABDALLAH2, HARTWIG H. GEIGER1 AND
ABDELBAGI M. ALI2
1
Institute of Plant Breeding, Seed Science, and Population Genetics (350), University of
Hohenheim, D-70593 Stuttgart, Germany;
2
Agricultural Research Corporation, Bio tech. Center, Khartoum , Sudan. PO. Box 30.
Keywords: Sorghum, breeding strategies, marginal conditions, traits
Sorghum (Sorghum bicolor (L.) Moench) is a staple food for the majority of
people living in the semi-arid areas of the Sudanian/Sahelian zone of Africa
where most sorghum cultivars are specifically adapted to the respective
climate. Under rain-fed conditions in Sudan, average grain yields are low and
variable ranging from 0.5 to 0.8 t/ha. Farmer-preferred cultivars are genetically
heterogeneous but display a low level of heterozygosity. The heterozygosity
level of a population is a function of its outcrossing rate (t). Continued selfing (t
= 0) leads to complete homozygosity whereas outcrossing (t = 1) leads to high
heterozygosity, coming close to that of hybrids. Numerous studies have shown
that not only yield, but also yield stability is improved with increasing degrees of
heterozygosity, mainly in allogamous, but also in autogamous (i.e. selfpollinating) species (Becker, 1993). Further, it has been shown that particularly
under marginal conditions and drought highly heterozygous sorghum can show
up to 107% higher yield in comparison with homozygous lines, whereas the
highest estimates have been reported in the lowest yielding environments
(Haussmann et al., 2000). Similar results have been reported for barley, where
highly heterozygous material showed up to 45% higher yield than lines in the
most stressful environment (Einfeldt, et al., 2005). Increasing the level of
heterozygosity, also in predominantly autogamous species such as barley and
sorghum could be achieved through hybrid breeding, however, only with much
time spent and at high costs. Furthermore, hybrid varieties are not affordable
for subsistence farmers in developing countries, where often neither a
commercial seed market nor infrastructure exists to dissemination. Moreover,
farmers cannot maintain hybrid variety performance when they save their seed
on farm.
An alternative strategy to achieve increased level of heterozygosity in sorghum
may be recurrent selection (RS). It is known that different varieties of sorghum
exist with distinct degrees of outcrossing (Rabbi et al., submitted) implying that
outcrossing rate is a heritable trait. Environmental effects on the expression of
this trait, however, point at a quantitative inheritance. Increasing outcrossing
rates of predominantly autogamous crop species should thus be possible by
means of recurrent selection. Recurrent selection is a cyclic breeding system
35
Traits for ideotypes
aiming at a gradual increase in frequency of desirable alleles for a particular
quantitative trait without a marked loss of genetic variability. The basic
technique involves the identification of individuals with superior genotypes and
their subsequent intermating to produce a new population.
Sorghum is partially allogamous with outcrossing rates between 5 and 20%
depending on race, genotype and environment. With the availability of codominant molecular markers such as Simple Sequence Repeat (SSR) markers,
the level of observed heterozygosity can be determined in plant species and
outcrossing rates can be estimated rapidly.
Based on above assumptions a project has been conducted at the Institute of
Plant Breeding, Seed Science and Population Genetics to increase the level of
heterozygosity in barley (Hordeum vulgare L.) through recurrent selection
employing molecular markers. The results of the study (Nandety, 2010)
demonstrate over the course of 4 selection cycles a small but significant
increase in heterozygosity and thus the general validity of the approach.
However, due to certain shortcoming during the experimentation an increase in
outcrossing from 1.4 to 2.8% was realized only. Nevertheless, the latter results
encouraged us to follow up the approach in a larger project using sorghum as a
model. For this purpose, we further refined the Marker Assisted Recurrent
Selection (MARS) approach and were able to complete each RS cycle in only
one generation at two generations per year (i.e. main- and off-season). The
outcrossing rate was assessed indirectly by determining the average
heterozygosity of individual plants at six unlinked SSR marker loci. Highly
heterozygous plants were most likely products of an outcrossing event and, if
so, should carry genes for high outcrossing aptitude from their parents. Such
highly heterozygous plants were selected before flowering (employing
molecular markers) and transplanted to a pollen isolated crossing plot. In our
project we completed four of these RS cycles.
During the course of the experiment an increase of outrcrossing from initially
8% over 9%, 19%, 34% and finally to 48% was observed for populations of RS
cycles C0 to C4, respectively. Heterozygosity and inferred outcrossing rates
and agronomic traits were assessed on remnant seed from populations of all
selection cycles in a final replicated field experiment at two locations (Wad
Medani, irrigated and Damazin, rainfed). A significant increase in outcrossing
(from 15 to 35%) (Fig. 1) and observed heterozygosity (from 7 to 26%) was
achieved in populations over four RS cycles. The achieved increase in
heterozygosity was associated with significant improvement of all agronomic
traits tested. A surprising triplication of grain yield (Fig. 2) was observed
associated with changes in plants' morphology such as increased number of
tillers, increased panicle lengths and diameters, steeper leaf angles and
delayed maturity which may be the result of increase developmental and
genetic homeostasis. The equally large plasticity of all RS populations was
obvious by their ability to produce shorter plants (about -30 cm) under
36
Traits for ideotypes
favourable and longer (about + 40 cm) plants under drought stress conditions
in comparison with the base population.
Figure 1 (left). Change in frequency of genotypes with different level of
outcrossing in popu-lations during the course of four RS cycles.
Figure 2 (right). Change in grain yield (g/plant) across two environments in
sorghum populations at successive cycles of RS (C0-C4).
The study revealed the usefulness of MARS in accelerating the RS process
and increasing the efficiency and accuracy of constructing heterozygous
populations. Promising heterogeneous and heterozygous material has been
generated for development of high yielding sorghum varieties. Improvement of
37
Traits for ideotypes
agronomic traits during the course of the four RS cycles was by far higher than
expected and can mainly be explained by the generally low initial yield level of
the genetic material used in the base population. In addition to developmental
and genetic homeostasis, plant morphology changes observed, may imply
features of sorghum ideotypes for drought prone environments. Although
results may have direct implications for sorghum breeding strategies under
marginal conditions, stability of increased outcrossing behaviour of obtained
populations needs to be evaluated in subsequent field experiments.
Literature
Becker, H. 1993. Pflanzenzüchtung. Ulmer Verlag, Stuttgart.
Einfeldt, C.H.P., S. Ceccarelli, S. Grando, A. Gland-Zwerger and H.H. Geiger. 2005. Heterosis and
mixing effects in barley under drought stress. Plant Breeding 124:350-355.
Haussmann, B.I.G., A. B. Obilana, P. O. Ayiecho, A. Blum, W. Schipprack, and H. H. Geiger.
2000. Yield and yield stability of four population types of grain sorghum in a semi-arid area of
Kenya. Crop Sci. 40:319-329.
Nandety, A. 2010. Recurrent Selection for Increased Outcrossing Rates of Barley from Semi-arid
Regions of Syria and Jordan. PhD-thesis, University of Hohenheim, Stuttgart, Germany.
Rabbi, I.Y., H.H. Geiger, B.I.G. Haussmann, B. C. Reddy, and H.K. Parzies. Outcrossing rates of
sorghum cultivars from two contrasting agro-ecosystems in Kenya and Sudan. Submitted to
Genetic Resources and Crop Evolution, 2010.
Contact: h.parzies@uni-hohenheim.de
38
Traits for ideotypes
Effect of phenological variation on photoperiodic
sensitive sorghum production in the Sahel
LANSAH ABDULAI1, MAMOUTOU KOURESSY2, MICHEL VAKSMANN3,
MOHAMED TEKETE2, KANE MAHAMADY2, FOLKARD ASCH1, MARCUS GIESE1,
HOLGER BRUECK1
1
University of Hohenheim, Stuttgart, Germany
IER, Bamako, Mali
3
CIRAD, Bamako, Mali
2
Studies were conducted to characterize diverse sorghums varieties adaptation
to climate change at the Institut d’Economie Rurale (IER) of Mali in three sites
covering latitude and rainfall gradients. Experimental sites were Cinzana
Agronomic Research Station (600 mm rain fall, latitude 13° 15 N, longitude 5°
58 W); Sotuba Research Station (900 mm rainfall, latitude 12° 39 N, longitude
7° 56 W) and Farako research Station (1000 mm, latitude 11°21 N, longitude
5°46 W).
A split plot design with planting date as main factor and varieties as sub factor,
in a randomized complete block design (RCBD) was used. 200kg/ha of “15N15P205-15 K20 were applied 2 weeks after seedling emergence while 50kg/ha
of urea (46N-0-0) were side dressed 4 weeks after seedling emergence.
Dates of phonological phases for each variety were scored from emergence to
panicle initiation. Above ground biomass was also measured (stems, leaves,
panicles).
Results indicated that most varieties react to variation in sowing dates by
reducing their cycle (emergence to maturity) from 7 to 20 days from north to
south gradients (13°N to 11°N). This is a consequence of varieties sensitivity to
day length (photoperiod). Total biomass was reduced (50 to 800g m-²) with
vegetative phases shortening. There exists great variability among varieties
within and between sites on total biomass produced. This variability is due to
threshold differences in varieties sensitivity to photoperiod. These results justify
well the early sowing practices of Sahelian farmers which support reasonable
use of their biodiversity in order to better exploit early rain falls. These practices
are to mitigate climate change effects.
Keywords: sowing dates, photoperiod, biomass, sorghum, biodiversity and
climate change.
Contact: alabdulai@yahoo.co.uk
39
Traits for ideotypes
Phenological Responses of Upland Rice Grown
Along an Altitude Gradient
SUCHIT SHRESTHA1, FOLKARD ASCH1, HOLGER BRUECK1, ALAIN
RAMANANTSOANIRINA2, JULIE DUSSERE3
1
University of Hohenheim, Department of Crop Production and Agroecology in the Tropics and
Subtropics, Crop Water-stress Management Section, Stuttgart, Germany
2
National Center for Applied Research and Rural Development (FOFIFA), Research Unit in
partnership for Sustainable Farming and Rice Cropping Systems, Antsirabe, Madagascar
3
Agricultural Research for Developing Countries (CIRAD), Research Unit in partnership for
Sustainable Farming and Rice Cropping Systems, Antsirabe, Madagascar
Crop adaptation strategies are required in terms of varietal development and
crop management to avoid negative impacts of climate change. In order to
characterize the agronomic fit of a potential upland rice ideotype, the
phenological response of ten selected upland rice varieties were studied on
three different altitude gradient locations (low altitude 25 m asl, mid altitude 965
m asl and high altitude 1625 ma asl) in Madagascar, ranging from hotequatorial conditions to the lower limit of the crop’s thermal adaptation.
Genotypic phenological responses were studied by closely observing the time
required to panicle initiation, booting, heading, flowering, and physiological
maturity. Above ground biomass, grain yield and yield components, and
spikelet sterility were recorded for each genotype and planting dates from all
the three locations for two years. Depending on genotypes, the duration from
germination to flowering stage ranged between 100 and 146 days in the high
altitude condition, whereas in the mid altitude it ranged between 73 and 97
days, and between 56 and 80 days in the low altitude as the mean air
temperature gradually increases to the lower altitude. The local landrace
genotype Botramaintso has the longest crop duration in all the three locations,
however the duration reduced in the lower altitudes. All genotypes yielded
better in the lower altitudes as the total sterility due to heat and/or cold is
minimum during cropping period. In the high altitude, genotypes such as
Chomrong, and FOFIFA 161, FOFIFA 167 and FOFIFA 172 produced more
grain yield. These cold tolerant genotypes have above average yield stability.
Variation in cold tolerance can be used to adapt genotype to different
environments. Morpho-physiological traits contributing to cold tolerance need to
be identified for further breeding. Phenological responses, photo-thermal
effects and sterility will be discussed and presented for an altitude gradient
upland rice cropping system.
Keywords: crop adaptation, crop duration, phenology, photo-thermal,
RISOCAS
Contact: suchitps@uni-hohenheim.de
40
Traits for ideotypes
Climate change impacts on African Agriculture:
ideotypes to adapt crops to climate change with
emphasis to barley in Ethiopia
BERHANE LAKEW
Holetta Agricultural Research Center, Ethiopian Institute of Agricultural Research. P.O.Box 2003,
Addis Ababa, Ethiopia
Keywords: Climate change, Ideotypes, Adaptation, Africa, Barley
Introduction
Climate change is expected to have serious economic, social and
environmental impacts in Africa in general and sub-Saharan Africa in particular.
Many Sub-Saharan African economies depend on agriculture for their
livelihoods. For some of them, agriculture accounts for as much as 40 percent
of the total export earnings and employs about 60-90 percent of the total labor
force (Hubert 2009). The major agricultural systems in Africa are climate
dependent, as most of sub- Sahara relies mainly on rain-fed agriculture. Due to
changed rainfall patterns, a decrease in fertile arable land and more extreme
weather events, agricultural production is likely to decrease. Under a fast global
warming scenario, large areas of Africa would experience changes in
December-February or June-August rainfall that significantly exceed natural
variability, with significant consequences on agricultural systems (Hubert
2009). Food security diminishes with an increase in the frequency of extreme
weather situations. According to the Intergovernmental Panel on Climate
Change (IPCC 2007), projected reductions in yield in some countries could be
as much as 50% by 2020, and crop net revenues could fall by as much as 90%
by 2100, with small-scale farmers being affected the most. There is urgent
need for adaptation of the agricultural sector to the changes in climate.
Climate change and Agriculture in Africa
Climate change could be particularly damaging to countries in Africa, being
dependent on rain-fed agriculture and under heavy pressure from food
insecurity and often famine caused by natural disasters such as drought, is
likely to be affected (Mendelsohn and Tiwari 2000). One fundamental
characteristic of rain fed agriculture is the variability of rainfall both within and
between seasons and the underlying uncertainty this imposes on production.
The area suitable for agriculture, the length of growing seasons and yield
potential, particularly along the margins of semi-arid and arid areas, are
expected to decrease (Mendelsohn and Dalfet 2000). There is a general
decline in most subsistence crops such as sorghum in Sudan, Ethiopia, Eritrea
and Zambia; maize in Ghana; millet in Sudan; and groundnuts in Gambia
(UNFCC 2007). In general climate change will severely affect African
agricultural and the many millions of people who are dependent on it.
41
Traits for ideotypes
Increasing agricultural productivity by improving yield levels of important
African staple crops through technological advances is required. Development
of several new varieties and traits offer farmers greater flexibility in adapting to
climate change, including traits that confer tolerance to drought and heat,
tolerance to salinity, and early maturation in order to shorten the growing
season and reduce farmers’ exposure to risk of extreme weather events
(Lybbert and Summer 2010). Understanding farmers’ response to climatic
variation is therefore crucial in designing appropriate copping strategies to
climate change for many poor countries that are highly vulnerable to effects of
climate change. African farmers pursue a wide range of crop and livestock
enterprises that vary not only within but across the major agro-ecological
zones. Even at the level of the individual farm unit, farmers typically cultivate
various crop types in diverse mixtures, depending on soil type, topographical
position, and distance from the household compound. Such Diversification and
mixed-cropping systems diminish risk, reduce crop losses from pests and
diseases, and make for more efficient use of farm labor.
Ideotypes to adapt climate change – barley
Barley (Hordeum vulgare ssp. vulgare L.) is the world’s fourth most important
cereal crop, after wheat, maize, and rice and the fifth most important food crop
in Ethiopia (Table 1), contributing 9.87 % of the total area and 9.41 % of the
total production of grain (CSA 2006, 2007 & 2008). The diversity of barley
ecology is quite high with a large number of landraces and traditional practices
in Ethiopia, which enables the crop to a wider plasticity of adaptation in the
different agro-ecologies and production systems. It sustains a livelihood of
millions of people residing on the highlands (Zemede 2002) and fetches a
substantial income for farmers. It is widely grown in diverse rain-fed agroecological zones of Ethiopia at altitude of 1500 to over 3500 meters. The fact
that agriculture is largely traditional and rain fed, that weather conditions play
an important role (Diao and Pratt 2007), makes the issue of climate change of
particular importance for Ethiopia
Ethiopian farmers grow barley because it has several advantages over other
cereals grown in the country: (1) barley can be grown in marginal areas where
the choice of other cereals is practically limited; (2) it offers the farmer an
earlier crop harvest than most cereals, providing relief of food shortages during
the long rainy season; (3) it has better stability of production over other cereals;
(4) it is a dependable food crop as it is grown in different seasons and
production systems; and (5) its straw is highly palatable for livestock.
42
Traits for ideotypes
Table 1: Cereal Production – Estimates of Acreage and Production. Source:
Author’s computation using Central Statistics Authority (CSA) data (CSA (July
2006), CSA (July 2007), and CSA (June 2008))
Average- 2004/2805 – 2007/2008
Crop
Grain
Area cultivated in hectares
Level
Share in total
area cultivated %
10,382,365
Production in quintals
Level
Share in total
production %
140,902,733
Cereals
8,230,211
79.27
120,628,724
85.61
Teff
2,237,850
21.55
24,079,480
17.09
Barley
1,024,390
9.87
13,264,217
9.41
Wheat
1,439,098
13.86
22,933,077
16.28
Maize
1,595,238
15.36
33,142,865
15.73
Sorghum
1,429,886
13.77
22,161,808
15.73
1,384,488
13.33
14,955,466
10.61
Oil Seeds
767,655
7.39
5,317,543
3.77
Minor grains
503,760
4.85
5,048,277
3.58
Pulses
The concept of crop ideoptypes was introduced by Donald (1968) to design
plants ideotypes with enhanced yield potential based on a composition of
favorable traits. Ideotype breeding gives higher priority to sets of individual
traits than selection for yield per se (Donald 1968). In barley, the most
consistent traits associated with higher grain yield under a changinging climate
such as drought are growth habit, early growth vigor, and earliness, plant
height under drought, long peduncle and short grain filling duration (Acevedo
and Ceccarelli 1989; Ceccarelli et al. 2004). Cattivelli et al. (1994) reported
additional morphological and physiological traits linked to drought resistance
such as tillering, root development, plantlet vigor, leaf water potential, stomata
size, membrane stability, desiccation tolerance, leaf rolling, waxiness, leaf
temperature, carbon isotope discrimination and the accumulation of
metabolites such as proline and betaine. A field experiment conducted in the
drought stress sites of Syria (Berhane et al. 2009) with a set of diverse barley
germplasms from Syria, Ethiopia and Australia indicated that among the
developmental and yield related traits measured, growth vigor, peduncle
length, plant height, days to heading and thousand kernel weight were mostly
associated with grain yield with moderate to high heritability under drought
conditions. In another field experiment conducted in Ethiopia (Sinebo et al
2009) to assess the genotype by environment interaction of diverse barley
genotypes under different management options, traits such as early vegetative
43
Traits for ideotypes
shoot height growth and heading time were important traits observed for yield
improvement in a year of high season-end drought. A number of adaptive traits
are present in the current Ethiopian germplasm pools for which phenotypic
selection can be applied. Thus, a combination of adaptive morphological and
agronomic traits of breeding value could provide the basis for developing new
varieties through targeted crossing programs to adapt a changing climate in
Ethiopia.
References
Acevedo E, Ceccarelli S., 1989 Role of physiologist-breeder in a breeding program for drought
resistance conditions. In ‘Drought resistance in cereals’. (Ed FWG Baker) pp.117-139.
Cattivelli L, Delogu G, Terzi V, Stanca AM (1994) Progress in barley breeding. In: Slafer GA (ed)
Genetic improvement of field crops. Marcel Dekker INC, New York, pp 95-181.
Ceccarelli S, Grando S, Baum M, Udupa S., 2004 Breeding for drought resistance in a changing
climate. In ‘Challenges and strategies for dry land agriculture’ (Ed CA Roberts) pp 167-190.
(Crop Science Society of America Inc and American Society of Agronomy Inc, Madison,
Wisconsin)
Central Statistics Authority (CSA) data CSA (July 2006), CSA (July 2007), and CSA (June 2008).
Diao, X., and A. N. Pratt, 2007 ‘Growth options and poverty reduction in Ethiopia: An economywide model analysis’, Food Policy 32(2):205-228.
Donald, C.M. 1968. The breeding of crop ideotypes. Euphytica 17: 385–403
Hubert E. Meena, 2009. African Progress and Effectiveness in International negotiations Leading to
the Post -2012 Climate Change Treaty, CEEST Foundation, Dareselam, Tanzania,
IPCC ,2007. Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability Summary for Policymakers. Contribution of Working Group II to the Fourth Assessment Report
of the IPCC.
Lakew B, Eglinton J, Henry R J .Baum M, .Grandod, S and .Ceccarelli S., 2010 The potential
contribution of wild barley(Hordeum vulgare ssp. spontaneum) germplasm to drought tolerance
of cultivated barley(H. vulgare ssp. vulgare)
Lybbert, T., and Sumner D., 2010. Agricultural Technologies for Climate Change Mitigation and
Adaptation in Developing Countries: Policy Options for Innovation and Technology Diffusion,
ICTSD–IPC Platform on Climate Change, Agriculture and Trade, Issue Brief No.6, International
Centre for Trade and Sustainable Development, Geneva, Switzerland and International Food &
Agricultural Trade Policy Council, Washington DC, USA.
Donald, C.M., 1968. The breeding of crop ideotypes. Euphytica 17: 385–403
Mendelsohn R & Tiwari D, 2000. Two essays on climate change and agriculture: A developing
country perspective. FAO Economic and Social Development Paper 145. Rome, Italy.
Mendelsohn, R. Dinar, A, and Dalfet, A., Climate change impacts on African Agriculture, The
WorldBank, Washington, DC, 2000.
Sinebo W, Lakew B, Feyissa A.,2010. Biplot analysis of grain yield in barley grown under differing
management levels in years of contrasting season-end drought . Journal of Plant Breeding and
Crop Science Vol. 2(6), pp. xxx-xxx,
United Nations Framework Convention on Climate Change (UNFCCC), Climate Change: Impact,
Vulnerabilities and Adaptation in Developing Countries, Climate Change Secretariat, Bonn,
Germany, 2007.
Zemede, A., 2002. The Barley of Ethiopia. Pp 77-107. In: Stephen, B.B (ed.). Genes in the Field.
On-farm Conservation of Crop Diversity. Lewis Publisher, Boca Raton.
Contact: berhanekaz@yahoo.com
44
Traits for ideotypes
Morphological traits for sorghum ideotype development to cope with climate variability in Africa
LANSAH ABDULAI1,2, HOLGER BRUECK1, MAMOUTOU KOURESSY3, MICHEL
VAKSMANN3, FOLKARD ASCH1
1
Univ. of Hohenheim, Dept. of Plant Prod. and Argoecol. in the Trop. and Subtrop., Germany
Savanna Agricultural Research Institute, Scientific Support Group
3
Institut d’Economie Rurale (IER), Mali
2
Climate change is forecast to adversely affect agriculture in the tropical arid
and semi-arid areas. The contribution of grain sorghum production systems to
the economy and food security of the populace of these regions could be
affected if climate changes. Adapting these systems to climate change in the
arid to semi-arid tropics (ASAT) would require ideotype traits that can enhance
among others, plasticity of crop cyles, tolerance to drought, delayed start of
senescence and maintenance of green leaf area (staygreen) and/or reserve
mobilization during grain development. A pool of diverse traits and well
established breeding methodologies exist, but the magnitude and specificity of
response to changed climates, of these genotypes need to be determined via
field research. Field experiments involving split plot arrangements of date of
sowing (mainplot factor) and genotypes (subplotfactor), were tested in a RCBD
with 3 replications at 3 locations (Farako, Sotuba and Cinzana) along a
latitudinal gradient in Mali during 2008 and 2009. The aim was to determine the
grain yield response and relationships between yield and key morphological
traits of the ten diverse grain sorghum genotypes. Data were recorded on
morphological traits such as features of the largest leaf area, length and width,
total leaf number, time from sowing to ligulation of the flag-leaf (in days and
GDD)], plant height, maximum leaf area index, leaf area duration, harvest index
and grain yield (GY). Relationships between GY and each of the other traits
were tested by Pearson correlation.
-2
Grain yield response to variation in sowing date ranged from 0 to 475 g m , 0
-2
-2
to 319 g m and 0 to 431 g m at Farako, Sotuba and Cinzana respectively. All
main effects represented significant sources of variation in GY at all the sites.
First order interactions, except year and variety at Sotuba significantly affected
GY. Second order interactions were also significant sources of yield variation at
Farako and Sotuba but not Cinzana. Across factors, a weak positive correlation
was observed between HI and GY while there was no relationship between GY
and the rest of the traits. The significant interaction between genotype and
location and genotype and sowing date for GY indicate that genotypic
variability can be exploited in order to adapt sorghum production systems to
variable climate. The implications for both modelling and development of
appropriate ideotypes are highlighted and discussed.
Keywords: sorghum genotypes, latitudinal gradient, G*E interaction, yield
45
Traits for ideotypes
What farmers want: farmer requested traits for major
crops on a climate gradient in West Africa
H.M. OUMAROU1, L. HERRMANN1, B.I.G. HAUSSMANN2, J. NAAB3, M.
OUEDRAOGO4, K. TRAORE5
1
University of Hohenheim 310, Stuttgart, Germany
ICRISAT, Sahelian Centre, Niamey, Niger
3
SARI, Wa, Ghana
4
INERA, Ouagadougou, Burkina
5
IER, Bamako, Mali
2
The hypothesis that agricultural phytodiversity contributes to adaptation to a
changing and variable climate was assessed in the CODE-WA project applying
a zonal approach covering four sites on an agro-ecological gradient in West
Africa: Niger (N-Sahelien), Mali (transition S-Sahelian - N-Sudanian), Burkina
Faso (S-Soudanian), Ghana (N-Guinean). Varietal performance under different
climate conditions was studied using multi-location GxE trials on-station and
on-farm in 2008-2010 seasons. With the aim to introduce new crops and
varieties direct on-farm comparison of local and introduced varieties were
performed going along with participatory evaluation, use of the opposite
pyramid approach and culinary testing. Traits important for performance and
farmer preference at different sites during different seasons and reasons
farmers stated for choosing a specific crop or variety are presented. The
results show that earliness is an important trait for farmers. This preference is
not only due to climate change but also due to economic and food security
issues. We noted that earliness in the sense of farmer statements is a relative
rather than absolute trait. In wetter zones, photoperiod sensitivity is requested
for major cereal staples. In addition, for staple as non-staple crops non-yield
related traits like taste and storage behavior after processing are important in
the farmers' view. These traits are difficult to incorporate in ordinary breeding
programs unless local germplasm is used as a basis. Some requested traits
like stay green are gender specific. In conclusion, requested traits are
numerous and depend on different aspects like multiple uses, economic return,
climate variability and food security. There is no “one-size-fits-all” solution for
any of the crops investigated. Under these conditions, efficient breeding
strategies need close contact with the farmers in order to respond to their
needs.
Keywords: G*E trials, participatory selection, climate variability, zonal gradient,
CODE-WA project
Contact: ludger.herrmann@uni-hohenheim.de
46
Traits for ideotypes
Rice Panicle Temperature and Crop Microclimate in
Stressful Thermal Environments: Towards a Model
of Spikelet Sterility.
CECILE JULIA, MICHAEL DINGKUHN
CIRAD, BIOS Department, Montpellier, France
Rice inflorescences are sensitive to chilling and heat, resulting in spikelet
sterility. It is not the air temperature itself, however, that causes the stress but
the temperature of the sensitive tissues during specific developmental stages.
Chilling affects sterility mainly through (1) disruption of meiosis during
microspore stage (tissues located at bottom of canopy exposed to floodwater
temperature at the beginning of booting) and (2) failure of panicle exertion
(temperature of elongating internodes at mid height of canopy). Heat affects
mainly pollination and fertilization processes at anthesis at the top of the
canopy. The organs concerned can have markedly different temperature from
air by up to 6°, depending on microclimate generated by the architecture,
roughness and transpiration rate of the canopy. Quantifying and predicting
these complex thermal relationships is essential to evaluate the impact of
climate change scenarios and the adaptation of cultivars to them. So far, no
crop model is available to simulate crop microclimate dynamics and to link
them to physiological processes.
This study, conducted in the context of the GTZ-funded RISOCAS project, aims
as a first step to observe experimentally on 7 contrasting varieties of irrigated
rice at climatically contrasting sites (Senegal, Philippines, Camargue in France)
the thermal relationships and components of the crop heat balance. This
includes diurnal soil, water, canopy, panicle and air temperature patterns and
their relationship with canopy structure and weather. First results are presented
from the 3 environments, notably vertical temperature gradients in the canopy
and temperature distribution with the panicle, using infrared photography and
thermocouples, as well as heat balance measurements and recordings of
nd
standard agrometeorology. As a 2 step, these observations will be related to
spikelet sterility and yield losses. Finally, the results will be used to develop a
micrometeorological module for the cereal crop models SARRAH and
EcoMeristem.
This paper presents first results, discusses methodological issues and provides
an outlook on the planned modelling approaches.
Keywords: oryza sativa, thermal stress, panicle sterility, microclimate, panicle
temperature, modelling, climate change
Contact: cjulia@irrialumni.org
47
Traits for ideotypes
Effect of temperature on relative yield and duration
of lowland rice under water-saving irrigation
SABINE STÜRZ1, ABDOULAYE SOW 2, BERTRAND MULLER2, BABOUCARR
MANNEH2 FOLKARD ASCH1
1
University of Hohenheim, Garbenstr.13, 50799 Stuttgart, Germany
Africa Rice Center, B.P.96, St.Louis, Senegal
2
With increasing water scarcity and climate variability the demand for water
saving crop production is growing. For irrigated rice as one of the largest
consumers of fresh water resources, several water-saving practices have been
identified and already adopted. Water-savings of up to more than 60% have
been reported, but the impact of water-saving irrigation on grain yield is highly
variable. Reported effects on grain yield vary from severe yield reductions to
yield increases in comparison to flooded fields.
Rice production in the Senegal River Valley strongly depends on intra-annual
climatic variation with a hot and dry period from March to July, a short wet
season from August to October, and a cold and dry period from November to
February. During the hot season, heat sterility as well as high water losses due
to extreme vapor pressure deficits are common. The cold season is
characterized by low development rates and high yield losses due to cold
sterility. These variable conditions are ideal for studying genotype-byenvironment interactions in order to assess genotypic traits with regard to their
suitability to specific environments.
For the ongoing study, 10 contrasting genotypes were selected representing
the large variation in the global gene pool in terms of duration, water use, and
heat and cold tolerance. In bi-monthly sowing dates, irrigation water input, yield
and physiological parameters were observed at 2 climatically different sites
under flooded and non-flooded conditions in order to identify genotypic traits
supporting water limited rice production as well as stable high yields under
varying thermal conditions. Weather parameters as well as floodwater
temperature were recorded.
Water input under water-saving irrigation relative to flooded fields ranged from
0.3 to 1.17 and was mainly dependent on soil texture, ground water table and
precipitation. Relative yield varied from 0.2 to 1.15 and was found to be highly
dependent on varietal characteristics as well as weather conditions. Whereas a
strong positive correlation between the relative yield of IR64 under watersaving conditions and the Tmin over the cropping period was found, coldtolerant upland variety Chomrong showed relatively stable relative yields over
different seasons.
Floodwater temperature (Tw) recordings showed that mean Twmin over the
cropping period was up to 2°C higher than air temperature. This effect was
greater during the cold period. Especially in the cold season, the extended
duration in the water-saving treatment, where plants were exposed to air
48
Traits for ideotypes
temperature, compared to flooded conditions, where plants were exposed to
floodwater temperature, confirms this difference in microclimate due to higher
floodwater temperature. This temperature effect appears to have a negative
impact on relative yield of IR64, but not on Chomrong, and might explain the
variability of the reported results of the impact of water-saving irrigation on
relative grain yields. Thus, tolerance of lower temperatures without a decrease
in yield is an important trait to improve the yield stability in water-saving
irrigation systems.
Keywords: Irrigated rice,
interactions, cold tolerance
water
temperature,
genotype-by-environment
contact: sabine.stuerz@uni-hohenheim.de
49
Modelling for ideotype development
Crop Modelling for Genetic Improvement and
Adaptation to Climate Change
KENNETH J. BOOTE
Department of Agronomy, University of Florida, USA
Genetic improvement of crop plants is important to increase world food supply,
in view of the continued increase in world population, soil degradation, climate
change, and limited resources. With the recent advances in dynamic crop
growth simulation and molecular technologies, crop models have excellent
potential for evaluating genetic improvement, linking to genetic markers, and
proposing plant ideotypes for target environments (Yin et al. 1999, Boote et al.
2001, Boote et al. 2003, Tardieu 2003, Hammer et al. 2005, Hammer and
Jordan 2007). It is timely to extend these efforts to genetic improvement in lowinput agricultural regions. Dynamic crop growth models compute a crop C, N,
and water balance on a daily (or hourly) basis. There are detailed equations in
the crop models for describing C, N, and soil water balance processes (Boote
et al. 1998). The crop models respond dynamically to daily weather and soil
conditions. The crop models integrate over multiple dynamic processes while
honoring C, N, and soil water balances, thus illustrating that yield requires and
is limited by inputs of water, N, solar radiation, and time (nothing is free).
The DSSAT crop models contain genetic characteristics that are vary
frequently among cultivars within a given crop (Jones et al., 2003). These
genotype-specific traits include day length sensitivities, life cycle phase
durations, seed size, seed composition, seed filling duration, leaf photosynthesis rate, specific leaf area, leaf size, rate of leaf appearance, etc (Boote
et al. 2001). These trait descriptions are generic and not linked to genes, but
efforts are needed to link molecular markers to “crop model” genetic
coefficients or specific processes in the dynamic models to see the integrated
effects of all traits to final yield. There are important built-in linkages and
feedbacks among real and modeled genetic traits. For example, a longer time
to anthesis allows a greater leaf area index (LAI) to be achieved by the time of
anthesis if all other traits were similar.
Dynamic crop growth simulation models can be used to hypothesize plant
genetic traits (phenology, process characteristics, and plant architecture) that
can potentially enhance crop growth and yield in defined target environments.
But first, it is important to define the target environment in terms of weather,
soils, management, fertility inputs, and initial cultivar type (desired life cycle).
Crop models can be simulated at several levels: 1) Level 1, with no limitations
from water and soil fertility (climatic yield potential), 2) Level 2, with limitations
of soil water-holding traits and rainfall (rainfed yield potential), 3) Level 3, with
limitations of water and N, 4) Level 4, considering limitations of water, N, as
well as other soil fertility limitations (P, K, micronutrients) and biotic stresses
(attainable yield). Actual attained yield, especially in Africa, is much lower than
50
Modelling for ideotype development
climatic potential yield or rainfed climatic potential yield or even water- and Nlimited yield, because of Level 4 limitations.
Genetic Improvement of Peanut Using the CROPGRO Model: Peanut seed
yields (Table 1) were simulated with genetic modification of the short-season
Chinese type cultivar using the CROPGRO-Peanut model under rainfed
conditions with 15 years of weather at Wa, Ghana, using a sandy loam soil with
good water-holding traits to 90 cm. Single and multiple trait combinations were
evaluated in four target environments. Yield of standard Chinese averaged
-1
1841, 2248, 1553, and 1770 kg ha at ambient CO2 (380 ppm), elevated CO2
(500 ppm), +3 ºC increase in temperature, and elevated CO2 plus elevated
temperature plus 20% less rainfall. Water stress was mild as rainfall was good.
Table 1. Peanut seed yield response to 10% change in cultivar coefficients
simulated for Chinese cultivar grown rainfed at Wa, Ghana with 15 years of
weather. Auto-sowing after sufficient rain. Initial soil water at 50% field
capacity.
Cultivar Coefficient Modified
Ambient
380 ppm
CO2
500 ppm
Yield /
% change*
Yield /
% change*
+3 ºC
temp
500 ppm CO2
+3 ºC temp
-20%RF
Yield /
Yield /
% change* % change*
-1
1841
2248
1553
1770
+10% Amax (leaf Ps)
7.3
6.4
6.9
5.4
+10% Specific Leaf Area
0.5
0.5
0.5
0.0
+10% EMFL
4.2
3.6
4.3
3.9
+10% SDPM
9.0
8.3
12.6
12.4
12.4
11.1
16.1
14.6
Chinese (std) (kg ha )
+10% EMFL&SDPM
+10% WTPSD (wt/sd)
0.7
0.8
0.7
0.5
-10% Pod Adding Duration
0.1
0.7
3.9
3.6
+10% XFRUIT (partitioning)
3.4
3.8
5.3
5.7
+10% SIZLF (veg. vigor)
1.5
1.4
0.9
0.8
EMFL, SDPM, XFRT
16.5
15.5
21.3
19.7
EMFL, SDPM, Amax
20.4
18.0
22.7
20.3
EMFL,SDPM,XFRT, Amax
24.7
22.6
28.6
25.8
*Percent increase compared to Chinese standard cultivar
51
Modelling for ideotype development
A 10% longer grain-filling period (first seed to harvest maturity, SDPM) gave
the largest increase in seed yield (8.3 to 12.6% over four environments).
Increasing the time from emergence to first flower (EMFL) increased yield 3.6
to 4.3%. Chinese is a 90-day cultivar, so it is not surprising to see traits that
increased the life cycle (time to flower and time to maturity) would increase
yield. The combination of two traits (EMFL & SDPM) gave 11.1 to 14.6% yield
increases, with the simulated life cycle increased by only 6.5 days. Higher leaf
-2 -1
photosynthesis (from 1.20 to 1.32 mg CO2 m s ) increased yield by 5.4 to
7.3%. Partitioning (XFRUIT) increase from 0.74 to 0.84 increased yield by 3.4
to 5.7%.
Table 1 illustrates that we can use crop models to evaluate single and multiple
combinations of genetic traits to improve yield, and that additivity of traits
occurs in most target environments. The two-way and three-way combinations
of EMFL & SDPM & XFRUIT gave outcome similar to adding up the separate
effects. The three-way combination (EMFL & SDPM & XFRUIT) gave a 16.5%
increase and adding Amax to the two or three-way combinations gave 20.4 or
24.7% increases in yield. These variations in EMFL, SDPM, Amax, and
XFRUIT are less than half the possible genetic range, so they are quite
feasible. In fact, improved cultivars in Ghana (with later flowering, longer life
cycle, higher partitioning, and higher biomass from disease resistance) have
50% higher yield than the Chinese cultivar. Simulations of multiple trait
combinations on soybean yield in Iowa were found to be generally additive
(Boote et al. 2003), and some traits were management- and CO2-dependent. In
the peanut example (Table 1), the response to traits and the additivity of traits
was similar under elevated CO2 and even greater under elevated temperature.
Genetic Improvement of Sorghum Using with CERES-Sorghum Model:
Cultivar traits were modified for generic Indian sorghum cultivar using the
CERES-Sorghum model, simulated with 15 years of weather data at Wa,
-1
Ghana with the same soil as for peanut with 20 or 80 kg N ha . These
simulations (Table 2) illustrate the importance of defining the target
environment, as the yield responses to genetic modification were greater under
high N than under low N. Some of the responses were opposite under high
versus low N. Under high N “target environment”, sorghum grain yield was
increased by trait modifications that gave later anthesis (smaller critical short
daylength - P2O, or longer basic vegetative phase - P1), or higher LAI (shorter
P2O, increased P1, smaller PHINT, and increased G1). The commonality is
that all of these traits including later anthesis increased LAI, thus increasing
light interception, photosynthesis and yield. Under low N fertility, the same
factors that gave later anthesis or increase in LAI had the opposite effect to
reduce yield. This highlights the trait dependence on target environment. As
expected, increased grain fill period (P5) increased yield under high and low N.
Increasing G2 (scalar for partitioning of assimilates to the panicle) increased
grain yield with no relationship to LAI or life cycle duration or N fertility.
52
Modelling for ideotype development
Additivity of traits appeared to hold for CERES-Sorghum, a different crop
simulated with a different model, as it did with CROPGRO for peanut or
-1
soybean. At 80 kg N ha , the three-way combination of P1, P5, and G2 gave
11.1% yield increase (approximately additive of 2.3%, 2.3%, and 6.3%). An
important point is that the simulated yield responses and additivity were less if
the crop was simulated with low N fertilization.
Table 2. Grain yield response to modified cultivar coefficients with 20 or 80 kg N
-1
ha simulated with CERES-Sorghum grown rainfed at Wa, Ghana with 15 years of
weather. Auto-sowing after sufficient rain. Initial soil water at 50% of field
capacity. Split N applied at day 1 and 31.
Cultivar Coefficient Modified
Yield
(20 kg N)
% change
Yield
(80 kg N)
% change
LAI
(80 kg N)
2
-2
m m
Maturity
(both)
days
Standard: P1=410.0, P2O=13.60, P2R=40.0, P5=540.0, G1=3.0, G2=5.5, PHINT=49.00
-1
Standard simulation (kg ha )
1409
3367
3.79
101.5
P2O, 12.6 hr
-2.5
4.3
4.21
104.3
P2O, 14.6 hr
0.0
0.0
3.79
101.5
P1=369 GDD
2.9
-3.9
3.14
99.4
P1=451 GDD
-1.8
2.3
4.41
104.0
P5=486 GDD
-3.2
-2.9
3.79
98.7
P5=594 GDD
3.9
2.3
3.79
104.6
G1=0
0.9
-2.5
3.35
101.5
G1=6
-0.6
0.8
4.05
101.5
G2=5.0
-5.8
-9.2
3.79
101.5
G2=6.0
6.0
6.3
3.79
101.5
PHINT=44 GDD
-1.6
1.7
4.27
101.8
PHINT=54 GDD
1.5
-3.2
3.16
101.5
P1=451, P5=594
1.4
4.6
4.41
106.8
P1=451, P5=594, G2=6
7.7
10.0
4.41
106.8
P1451, P5=594,G2=6, G1=6
7.0
11.1
4.69
106.8
53
Modelling for ideotype development
References
Boote, K. J., J. W. Jones, W. D. Batchelor, E. D. Nafziger, and O. Myers. 2003. Genetic coefficients
in the CROPGRO-soybean model: Links to field performance and genomics. Agron. J. 95: 3251.
Boote, K. J., J. W. Jones, and G. Hoogenboom. 1998. Simulation of crop growth: CROPGRO
Model. Chapter 18. pp. 651-692. IN: R. M. Peart and R. B. Curry (eds.). Agricultural Systems
Modeling and Simulation. Marcel Dekker, Inc, New York.
Boote, K. J., M. J. Kropff, and P. S. Bindraban. 2001. Physiology and modelling of traits in crop
plants: implications for genetic improvement. Agricultural Systems 70:395-420.
Hammer, G. L., S. Chapman, E. van Oosterom et al. 2005. Trait physiology and crop modeling as a
framework to link phenotypic complexity to underlying genetic systems. Aust. J. Agric. Res.
56:947-960.
Hammer, G. L. and D. R. Jordan. 2007. An integrated systems approach to crop improvement. pp.
45-61. IN: J. H. J. Spiertz, P. C. Struik, and H. H. van Laar (eds.) Scale and complexity in plant
systems research: gene-plant-crop relations. Springer.
Jones, J. W., G. Hoogenboom, C. H. Porter, K. J. Boote, W. D. Batchelor, L. A. Hunt, P. W.
Wilkens, U. Singh, A. J. Gijsman, and J. T. Ritchie. 2003. The DSSAT cropping system model.
Europ. J. Agronomy 18:235-265.
Tardieu, F. 2003. Virtual plants: modelling as a tool for the genomics of tolerance to water deficit.
Trends in Plant Science 8:9-14.
Yin, X., M. J. Kropff, and P. Stam. 1999. The role of ecophysiological models in QTL analysis: the
example of specific leaf area in barley. Heredity 82:415-421.
Contact: kjboote@ufl.edu
54
Modelling for ideotype development
Climate change impact on maize yield and water and
nutrients utilization in Ghana: scenario analysis
using APSIM
BENEDICTA YAYRA FOSU-MENSAH, AHMAD M. MANSCHADI, PAULL. G. VLEK
Center for Development Research (ZEF), University of Bonn, Germany
Climate change and variability pose a serious threat to food production in the
sub-Saharan Africa. The projected changes in spatio-temporal patterns of
rainfall and temperature will likely affect water and nutrients availability and
utilization, crop growth, and yield formation. This paper presents the simulated
effects of climate change on maize (Zea mays L.) in the Ejura region of Ghana,
known as the food basket of the country. Experimental Data from maize grown
under different nitrogen (N) and phosphorus (P) regimes in 2008 major and
minor seasons at 2 sites in Ejura were used to parameterize and evaluate the
cropping systems model APSIM. Daily climatic data for the period 2030-2050
under the scenarios A1B and B1 (2030-2050) were obtained from the regional
mesoscale model MM5. Model evaluation revealed that APSIM was able to
successfully simulate the response of maize to water, N and P. The model
simulated maize grain yields with a coefficient of efficiency (r2) of 0.90 and 0.88
for Obatanpa and Dorke cultivars, respectively. Assessment of climate change
impact on maize grain yield by the model suggested a likely shift in the onset of
the rainy season with sowing dates occurring in about 70% of the years in the
2nd week of May compared to 3rd week of March simulated for the historical
weather data (1980-2000). This 6 weeks delay in sowing resulted in yield
reduction of on average 50% as well as a significant increase in yield variability
under both climate change scenarios. Simulation results indicate clearly that
maize yield is likely to decrease in the future in Ejura. Potential adaptation
measures include planting of early-maturity maize cultivars and introduction of
supplemental irrigation. The major conclusion is that developing productive and
resilient cropping systems will require implementation of site- and seasonspecific adaptation measures. For instance, depending on the onset of the
rainy season, farmers would need to have access to suitable maize varieties in
order to avoid significant yield losses in case of delayed sowing, while being
able to capitalize on favorable conditions in good seasons. This would require
development and availability of locally-adapted maize varieties with different
maturity periods.
Keywords: Africa, simulation modeling, water availability, crop management,
nitrogen, phosphorus, sowing date
Contact: manschadi@uni-bonn.de
55
Modelling for ideotype development
Improvement of data from highly heterogeneous
sorghum field trials in Mali employing geostatistical
methods
WILLMAR LEISER 1, FRED RATTUNDE2, HANS-PETER PIEPHO3, HEIKO K.
PARZIES1
1
University of Hohenheim, Institute of Plant Breeding, Seed Sciences and Population Genetics,
Stuttgart, Germany
2
ICRISAT, Sorghum Breeding and Genetic Resources, Bamako, Mali
3
University of Hohenheim, Institute of Bioinformatics, Stuttgart, Germany
A growing world population juxtaposed with diminishing fertilizer resources e.g.
phosphorous presents new challenges for current and future plant breeding.
The burden of low-input conditions is particularly felt in Sub-Saharan Africa as
many farmers don’t have access to fertilizer. Plant breeding for adaptation to
low-input conditions presents an opportunity to increase yields on farm level.
Spatial variability of plant nutrients and other growth factors is mostly higher in
low-input field trials. A four year multi-location experiment was conducted in
Mali, West Africa. Seventy sorghum genotypes were evaluated under low and
high input conditions. High spatial heterogeneity within each trial was observed
for plant available soil P content and different plant traits. Therefore spatial
adjustment models were applied to increase heritability and efficiency of each
trial. Data for grain yield were analyzed in each environment with 92 different
models including 82 models with autoregressive spatial correlation terms. A
column and row factor was given to each plot of a trial. Spatial models (AR1,
AR2) could significantly improve broad sense heritability and relative efficiency
of grain yield compared to randomized complete block (RCB) and lattice
designs. No specific model was best for all environments. Spatial models
increased genetic variance and reduced environmental error, leading to
different genotype ranking for grain yield compared to RCB. Improvement of
heritability and efficiency was greater in low-input trials. Thus the use of spatial
models is recommendable for trials with high soil heterogeneity and low broad
sense heritability values and therefore an important tool especially for plant
breeding trials under low-input conditions and other agronomical field trials
hampered by spatial heterogeneity.
Keywords: low-input plant breeding, sorghum, spatial adjustment
Contact: willmar_leiser@uni-hohenheim.de
56
Modelling for ideotype development
Phenotyping vs Ideotyping: Opportunities and
Limitations of model-assisted crop design drawing
from information on genetic diversity
DELPHINE LUQUET
CIRAD, AIVA “Agro-ecological Adaptation and Innovation of Varieties” research unit, Montpellier,
France
Keywords: plant modeling, physiological and genetic architecture, complex
traits, molecular breeding
Crop improvement & climate change: Place of phenotypic plasticity
Climate change and variability (CCV) is characterized by both a steady trend
leading to a global warming and an increasing frequency of extreme (drought,
thermal) events (IPCC 2007). Crop performance becomes more variable and in
many environments will show downward trends. Because it is forecasted that
this climatic trend will keep intensifying, there is a need today to breed for
varieties better adapted to future cropping conditions. This is particularly urgent
in developing countries where farmers mostly have limited capacity to
financially bridge a failed season or the technical means to minimize the impact
of climatic events on yield through improved cultural practices (Giese et al.
2009). Rice, the tropics’ foremost food crop, is particularly vulnerable because
of its high water demand and poor drought tolerance. Sorghum is a major food
crop in drought prone environments and has great potential for crop
improvement for food, feed and bio-fuel production (“FFF”). These two cereals
are thus of particular interest for developing new plant designs for changing
environments and uses.
Marker assisted selection (MAS) will strongly contribute to and accelerate
improvement of rice and sorghum because both are fully sequenced model
plants and possess a great genetic diversity which is crucial to rapid progress
in breeding (Cooper et al. 2002). To face CCV, genotypes are needed that
combine high yield potential, tolerance to warmer and drier conditions and
adaptive traits to tolerate highly variable environments. Inducible adaptive traits
are expected to provide the plant with phenotypic plasticity that helps
maintaining performance under fluctuating conditions. While breeders designed
varieties with reduced phenotypic plasticity as a way to achieve an optimal
plant type for favorable conditions to maximize potential productivity and
fertilizer response during the green revolution, it is obvious today that this
strategy is not adapted to meet forthcoming climatic challenges (Dingkuhn et
al. 2005). Phenotypic plasticity draws from the plant’s inherent capacity to
dynamically regulate its morphogenesis based on compensatory source-sink
processes and to optimize its productivity under fluctuating conditions (Nicotra
et al. 2010). Combining high yield potential with adaptive behavior to face CCV,
constitutive and inducible traits need to be further combined, implying an
57
Modelling for ideotype development
increase of potential Genotype X Environment interactions GxE. Care must be
taken to minimize trade-offs, potentially involving ‘counter-productive’ plasticity
through negative feedback on yield (Nicotra et al. 2010). Trade-offs exist not
only between adaptation and yield but also among multiple yield objectives,
e.g., sweet sorghum producing for ‘FFF’ (Gutjahr et al. 2010).
Plant modeling to support phenotyping and ideotyping: state of the art
Genetic analysis and breeding for complex traits such as grain yield, biomass
or sugar needs to address component traits that impact on the phenotypic
expression of the complex trait in a given set of environments. Component
traits are expected to be genetically and physiologically simpler but their
measurement must take into account GxE. Phenotyping of panels of cultivars
or lines is thus extremely sensitive to the choice of environmental conditions.
Molecular markers can then be derived from association mapping (providing
QTLs) and can be directly used for selection, provided that probability of
phenotypic expression is high. This is where the main hurdles reside: effective
expression in different genetic backgrounds and different environments needs
to be ascertained beforehand and requires (i) a sufficiently large and diverse
panel ensuring recurrence of useful alleles in different backgrounds, and (ii)
phenotyping methodology and environments expressing the useful loci/alleles.
During the last decade plant physiology and modeling demonstrated their
relevance in supporting the stepwise, upstream processes of molecular
breeding:
i)
Support for phenotyping: Plant physiology is increasingly providing
applied tools for phenotyping down to the molecular scale (eg. transcriptomics:
Takahashi et al. 2005). But still, association genetics mostly use rather crude
(but economical) phenotyping tools. Behavioral, plasticity traits, conditional to
environment, cannot be captured this way. Identifying their genetic basis
requires pairs of environments that make such traits observable, and models
that help extract the underlying reaction norm. A model formalizing the
response of a simple biological process (output variable) to external variable(s)
can be used to separate the G (genotypic parameters) from the E (input
variables) effects (Yin et al. 1999). By fitting the model, G parameters can be
quantified heuristically and can be considered traits in the genetic analysis.
Reymond et al. (2003) used a simple model of maize leaf expansion rate (LER)
response to soil water deficit, leaf to air vapor pressure deficit and temperature
to analyze the GxE in different temperate environments. QTLs detected for
model parameters were genotype specific and stable across environments;
they were also confirmed in another genetic (tropical) background (Welcker et
al. 2007). Here, QTLxE interactions were overcome by modeling that causing
QTL instability if detected with directly measured. Further progress is under
way in this field, eg. using architectural modeling in conjunction with image
analysis, or functional-structural plant model to extract parameters of
compensatory growth (Luquet et al. 2010).
58
Modelling for ideotype development
ii)
Support for ideotyping: The added value of elemental traits and related
QTLs for breeding cannot be estimated without considering their impact on the
performance of the whole plant system in a population context. This requires
crop models having sufficient detail of both varietal traits and environment
(including management), as well as interactions among them. The challenge is
to capture the interactions realistically to account for GxE (Hammer et al.
2010). If adaptation to CCV is the objective, the GxE simulations must be
sufficiently accurate to allow extrapolation of ideotype performance to
hypothetical scenarios. By introducing the LER model of Reymond et al. (2003)
into the APSIM crop model (Chenu et al. 2009), the effect of LER related QTLs
on grain yield was simulated for different genotypes and drought environments,
opening the door for in silico design of plant ideotypes. This study is probably
the first real proof of concept for ideotype simulation using crop models driven
by genetic parameters. Doing this for traits constituting phenotypic plasticity,
however, requires models with greater physiological detail.
Can plant modeling help molecular breeding in dealing with the genetic
and physiological architecture of complex traits?
An important obstacle to molecular breeding are the genetic and/or
physiological linkage among traits making difficult the study of a trait without
another (W. ter Steege et al. 2005). Many traits are not what they appear to be
because there are an indirect result of other processes. Models can help
explain emergent properties of the plant system difficult to apprehend
experimentally (Génard et al. 2010). Welcker et al. (2007) reported that some
QTLs controlling maize LER (Reymond et al. 2003) also control silk expansion
rate, and thus ASI (Anthesis to Silking Interval), with similar allelic effects.
Chenu et al. (2009) included into APSIM the pleiotropic effect of these QTLs on
both LER and ASI. Simulation experiments showed a positive impact of QTL
accelerating LER on yield under well watered conditions. Considering the
pleiotropic QTL effects on LER and ASI strongly affected yield, highlighting the
potential errors committed in ideotyping when the genetic architecture and
physiological trade-offs of a complex trait are not accounted for. The elemental
traits considered here (LER, ASI) are physiologically weakly linked as they
impact on yield at different developmental stages. Complexity increases
dealing with more interacting traits (Hammer et al. 2010), for example, that
regulating plant morphogenesis (plasticity) vs. drought responses.
Plants develop according to a specific construction plan that is implemented as
an orchestrated phenological process that can be more or less rigid or plastic.
Besides the responses of the organogenetic process itself to stresses, it
determines in a constitutive way resource use and thus, the probability and
intensity of stress occurrence such as drought. It involves several traits related
to the activity of the meristems having dynamic physiological feedbacks and
compensations among them (Granier and Tardieu 2009): e.g., organ initiation
rate, organ expansion rate and potential size, tillering, and geometric traits
59
Modelling for ideotype development
such as leaf or root angle. The result is a dynamic system of assimilate sources
and sinks that continuously adjusts its internal equilibrium as environment
changes, buffered by transitory reserve pools. It involves physiological
signaling because adjustment of organ size requires adjustment in cell number,
determined by meristem activity. Tisné et al. (2008), on A. thaliana, and W. ter
Steege et al. (2005) (on wheat) provided some first results on the genetic links
between plant leaf number and leaf epidermal cell area and number. These
findings indicate that the physiological linkages among morphological traits at
different organizational levels (cell to plant) are subject to genetic control and
not only physiological interaction. This in turn has consequences for the way
traits constituting morphological plasticity can be phenotyped and modeled
(Granier and Tardieu 2009). Can such traits be phenotyped separately or is a
systemic approach essential?
Genetically controlled response norms thus interact with environment to
generate adaptive, phenotypic plasticity. This is the concept behind the crop
model Ecomeristem (Luquet et al. 2010a). It simulates plant morphogenesis in
a population context at organ level, with GxE interactions through C source
feedback on sinks and development processes (supply/demand). Feedbacks
are tuned by G parameters. Luquet et al. (2010a; 2010b) used Ecomeristem to
explore the impact of genotypic development rate (DR) on the early vigor of
rice. Physiological feedbacks between DR, tillering ability, leaf size, expansion,
senescence and non structural C storage were demonstrated under optimal
and drought conditions, and their regulation seen as an expression of different
adaptation strategies. Greenhouse observations on a panel of 200 japonica
rices identified trait associations predicted by the model. Model parameters that
control the elemental traits of vigor were estimated for each genotype of the
panel. Genetic association mapping of genotypic parameter values will
evaluate the appropriateness of using Ecomeristem for phenotyping of complex
traits, the hypothesis being that structural-functional architecture will provide
keys to the architecture of genetic control. If confirmed, the approach will allow
designing ideotypes with greater confidence using models.
References
Chenu K, Chapman SC, Tardieu F, McLean G, Welcker C, Hammer GL (2009) Simulating the Yield
Impacts of Organ-Level Quantitative Trait Loci Associated With Drought Response in Maize: A
‘‘Gene-to-Phenotype’’ Modeling Approach. Genetics 183, 1507–1523.
Cooper DW, Poldich DW, Micallef KP, Smith OS, Jensen NM, Chapman SC, Kruger NL (2002)
Linking biophysical and genetics models to integrate physiology, molecular biology and plant
breeding (Chapter 11). In 'Quantitative Genetic, Genomics and PLant Breeding'. (Ed. MS
Kang) pp. 167-187. (CAB International)
Dingkuhn M, Luquet D, Quilot B, Reffye PD (2005) Environmental and genetic control of
morphogenesis in crops: Towards models simulating phenotypic plasticity. Australian Journal
of Agricultural Research 56, 1-14.
Génard M, Bertin N, Gautier H, Lescourret F, Quilot B (2010) Virtual profiling: a new way to analyse
phenotypes. The Plant Journal 62, 344–355.
60
Modelling for ideotype development
Giese M, Brueck H, Dingkuhn M, Kiepe P, Asch F (2009) Developing rice and sorghum crop
adaptation strategies for climate change in vulnerable environments in Africa RISOCAS. In
'Tropentag 2009'. University of Hamburg, Hamburg.
Granier C, Tardieu F (2009) Multi-scale phenotyping of leaf expansion in response to
environmental changes: the whole is more than the sum of parts. Plant , Cell and Environment
62, 1175-1184.
Gutjahr S, Clément-Vidal A, Trouche G, Vaksmann M, Thera K, Sonderegger N, Dingkuhn M,
Luquet D (2010) Functional analysis of sugar accumulation in sorghum stems and its
competition with grain filling among contrasted genotype. In 'Agro2010'. Montpellier, France
Hammer G, van Oosterom E, McLean G, Chapman C, Broad I, Harland P, Muchow RC (2010)
Adapting APSIM to model the physiology and genetics of complex adaptive traits in field crops.
Journal of Experimental Botany 61, 2185–2202.
IPCC (2007) 'Summary for Policymakers.' Cambridge, United Kingdom and New York, NY, USA.
Luquet D, Rebolledo MC, Soulié JC, Rouan L, Dingkuhn M (2010b) Developmental dynamics and
early growth vigour in rice 3. Model based and experimental exploration under drought
conditions. in preparation.
Luquet D, Soulié JC, Rouan L, Dingkuhn M (2010a) Developmental dynamics and early growth
vigour in rice 2. Importance in modelling biomass production of rice.
Nicotra AB, Atkin OK, et al. (2010) Plant phenotypic plasticity in a changing climate. Trends in Plant
Science 15, 684-692.
Reymond M, Muller B, Leonardi A, Charcosset A, Tardieu F (2003) Combining Quantitative Trait
Loci analysis and an ecophysiological model to analyse the genetic variability of the responses
of maize leaf growth to temperature and water deficit. Plant Physiology 131, 664-675.
Takahashi S, Ishimaru K, et al. (2005) Microarray Analysis of Sink-Source Transition in Rice Leaf
Sheaths. Breeding Science 55, 153-162.
Tisné S, Reymond M, VILE D, Fabre J, Dauzat M, Koormeef MG, C. (2008) Combined Genetic and
Modeling Approaches Reveal That Epidermal Cell Area and Number in Leaves Are Controlled
by Leaf and Plant Developmental Processes in Arabidopsis. Plant Physiology 148, 1117-1127.
W. ter Steege M, den Ouden FM, Lambers H, Stam P, Peeters AJM (2005) Genetic and
Physiological Architecture of Early Vigor in Aegilops tauschii, the D-Genome Donor of
Hexaploid Wheat. A Quantitative Trait Loci Analysis1[w]. Plant Physiology 139, 1078–1094.
Welcker C, Boussuge B, Bencivenni C, Ribaut J-M, Tardieu F (2007) Are source and sink strengths
genetically linked in maize plants subjected to water deficit? A QTL study of the responses of
leaf growth and of Anthesis-Silking Interval to water deficit. Journal of Experimental Botany 58,
339-349.
Yin X, Kropff M, Stam P (1999) The role of ecophysiological models in QTL analysis: the example
of specific leaf area in barley. Heredity 82, 412-421.
Contact: delphine.luquet@cirad.fr
61
Modelling for ideotype development
Latitude effect on the development of photoperiodic
sensitive sorghum
LANSAH ABDULAI1, MAMOUTOU KOURESSY2, MICHEL VAKSMANN3, FOLKARD
ASCH1 , MARCUS GIESE1, HOLGER BRUECK1
1
University of Hohenheim, Stuttgart, Germany - 2 IER, Bamako, Mali - 3 CIRAD, Bamako, Mali
Matching phenology with favourable abiotic and biotic conditions is a
prerequisite for good varietal adaptation. That is particularly important in a
context of climate change because the temperature increase is likely to modify
the precocity of the varieties. The forecast of the phenology of photosensitive
cereals is complex because flowering depends on both temperature and day
length. The effects of photoperiod and temperature can be studied by trials in
phytotron, but, high cost prohibits the use of this technique where large
numbers of varieties are handled. The day length varies with latitude. Multilocation field trials can be employed for creating a range of environments, but
in this type of trials, the great variability of the environments (mainly
photoperiod x temperature interaction) often masks the photoperiodic effect.
The maturity of the photoperiodic varieties is especially very variable according
to the sowing date. Trials comprising of several sowing dates facilitate the
study of the effect of small variations of photoperiod on phenology. The
objectives of this work are to compare these two last approaches by precisely
measuring the effect of the latitude on the development of selected varieties of
sorghum sown at staggered planting dates and to verify the precision of our
models to predict sorghum maturity. A field experiment in Mali was conducted
at the experimental sites of Cinzana (13°15' N), Sotuba (12°39' N) and Farako
(11°13' N) in 2009 and 2010. Six sorghum cultivars representing the diversity
cultivated sorghum in Mali were sown on three dates (10th June, July and
August). The study is related to the phenology and the phyllochrone on the
main stem. The effect of latitude on the phenology was underestimated by the
existing models. Although the day length difference between Cinzana and
Farako is less than 8 minutes, for some varieties we observed a variation in the
duration of the crop cycle of up to two weeks. Thus comparable small latitudinal
differences highly affected on photosensitivity. However, some varieties
respond non-photosensitive in Farako and photoperiodic in Cinzana. To
determine the optimal areas for the varieties in West Africa and to forecast the
effects of climate change, it is necessary to develop a new model that is able to
predict the effects of both, sowing date and latitude. Further research is needed
to understand physiological response mechanisms of the pronounced latitude
effects on phenology of sorghum.
Keywords: Sorghum, photoperiodism, latitude, sowing date
Contact: michel.vaksmann@cirad.fr
62
Modelling for ideotype development
Development of new sorghum ideotypes to meet the
increasing demand of bioethanol
S. BRACONNIER, G. TROUCHE, S. GUTJAHR, D. LUQUET, M. DINGKHUN
CIRAD, UMR AGAP, F-34398 Montpellier, France
Keywords: sweet sorghum, bioethanol, new ideotype, SAMARA model
Fossil fuels reserves are limited and we will reach the peak oil very soon, if not
already passed (http://www.oildecline.com). As we consume oil faster than we
discover new reserves, the price will inexorably increase in the next years. We
also know that in the future we have to reduce GHG emissions, of which large
part comes from the transport sector, to mitigate climate change. Thus it is
urgent to find alternative and sustainable energies. Biofuels or agrofuels,
defined as solid, liquid or gas fuels derived from biomass, are today the only
direct substitutes for oil on a significant scale particularly in the transport sector.
The development of biofuel production may result in the decrease of the
surfaces available for food production and then lead to a great instability of the
staple food market and finally to a dramatic increase of the food insecurity. To
avoid or minimize such negative impact, we have to identify new crop and
define future ideotypes able to meet the energy demand without compromising
food security.
Which plant for producing energy?
Considering bioethanol production, the two main sources currently used are
maize under temperate area and sugar cane in tropical area. If production from
sugar cane in Brazil has a positive energy balance, allows a great GHG saving
with a competitive price, production from corn in the USA results in less
positive if not sometimes negative balances. Sorghum (Sorghum bicolor L.
(Moench)) is one of the most efficient crops to convert atmospheric CO2 into
sugar with great advantages compared to sugarcane in the tropics and maize
in the temperate zone: (i) its growth cycle is short (about four months), (ii) the
crop can be established from seed, (iii) its production can be completely
mechanized, (iv) it produces sugar in stalk, and starch in grain, (v) it has a high
water and nutrient use efficiency, (vi) the bagasse produced from sweet
sorghum has high biological value when used as forage and (vii) it has a wide
adaptability to environment. Finally, unlike sugarcane and maize, sweet
sorghum has little breeding history and the potential of production improvement
through genetic enhancement is thus very high. It represents an alternative
energy crop.
The FP7 project “SWEETFUEL / Sweet sorghum: an alternative energy crop”
was elaborated to develop ethanol production from sweet sorghum in
temperate and tropical area through genetic enhancement and improvement of
harvest and cultural practices.
63
Modelling for ideotype development
Definition of new sorghum ideotypes
The target plant type depends on the environment and also on the type of
processing.
• In temperate climate, the sorghum ideotype can be defined as a
“biomass” sorghum, sweet or not, with or without grain. Its essential traits are a
(i) high biomass production with a good quality and homogeneity (low lignin
nd
content + good digestibility) suitable for 2 generation processing, (ii) a good
tolerance to cool temperature at the beginning and end of the season, (iii) high
water use efficiency to minimize irrigation requirements, and (iv) a phenology
suited to make maximal use of the summer season. The system is highly
mechanized and centralized.
First data showed it was possible to combine interesting traits like high biomass
production + low lignin content + good digestibility of fibers (figures 1).
• Under tropical area, situation is a little more complicated as we may
find centralized and decentralized systems with different objectives.
In Brazil, the first objective is to complement sugarcane production for
maintaining plants/distilleries at full charge all over the year (the issue is to
convert 20% of sugarcane area into sweet sorghum = 1.5 millions ha). In that
case, the target ideotype includes maximal stem soluble sugars with high
biomass production. Stem juicyness, sugar-°Brix% with tolerance to Al toxicity
and P deficiency are the main traits, secondary characters are a good
production of grains, high feed quality of biomass (low lignin). When
considering decentralized systems in Brazil, where the objective is to develop
production systems for providing a village or a cooperative with food and fuel,
grain production is an essential trait. Some results confirm that it is possible to
combine a high sugar concentration in juice with a high quantity of juice as well
as a high stalks production, while a gene for tolerance to Al toxicity (AltSB) is
being incorporated to best lines.
In India, where both centralized and decentralized systems exist, the target
ideotype is a triple f plant, producing food (grain), feed (bagass) and fuel
(ethanol from sugar in stalks). The main traits are stem juiciness, grain yield,
sugar-°Brix%, adaptation to rainy and post rainy seasons, stay green, low lignin
content, and biomass. First data on competition between grain production and
sugar accumulation in stalks showed there is a competition between the 2
sinks, but if we explore the diversity in sorghum, we can find some genotypes
combining good production of grain with high accumulation of sugars in stalks
(figures 2). Two sources of stay green with a high °Brix% were identified and
will be used in breeding programs.
64
Modelling for ideotype development
a.
b.
Figures 1: lignin content (a) and digestibility of fibers (b) according to the
biomass of stalk for 206 accessions (source: 2009 Grassbiofuel report)
a.
b.
Figures 2 : °Brix% value in 15 lines with or without inflorescence (a) and
according to fresh weight panicles among 12 accessions (b)
In the case of Haïti, where we can find some very contrasted situations in terms
of rainfall distribution and where we target a triple purpose crop (grain, ethanol,
fodder), an adapted phenology is essential as the favorable season around
Port au Prince (from April to August) is quite different from those near Cap
Haïtien (from October to February).
From the first observations conducted in different environments, the new target
ideotypes of sorghum are achievable giving this plant a good opportunity to be
a promising alternative energy crop in many environments.
Development of a new sorghum model
For the conception of new ideotypes, for the identification of their Target
Populations of Environment (TPE) as well as the study of their adaptation to
climat change or climat variation, we needed a new model able to simulate
particularly accumulation of reserves (sugars) in stalks.
65
Modelling for ideotype development
Based on ECOTROP software and on water balance and phenology modules
from SARRAH, the new model, SAMARA was developed (figure 3). As
calibration for sorghum is possible in many different environments, the model
seems quite robust. The first sensitivity analysis was performed by modifying
varietal parameters (plant height, cycle duration…) or agronomic practices
(irrigation, plant density…) or a combination of 2 parameters (height +
density…) before analyzing evolution of output values (panicle and grain yield,
total biomass, sugar yield, LAI…). On a qualitative basis, results of the
sensitivity analysis matches field observations. We need now to conduct
specific field experimentations to validate SAMARA for sorghum.
Figure 3: Example of the biomass outputs of SAMARA model for sorghum
Contact: serge.braconnier@cirad.fr
66
Poster – Crop improvement
Field evaluation of West African sorghum landraces
introgressed with genomic regions for resistance to
the parasitic weed Striga hermonthica
P. MUTH 1, S. KATILE 2, F.W. RATTUNDE 4, A. TOURÉ 3, H.K. PARZIES 1
1
Univ. of Hohenheim; Inst. Plant Breeding, Seed Sci. and Population Genetics; Stuttgart, Germany
Institut d’Économie Rurale (IER); Station de Cinzana; Ségou, 3Station de Sotuba; Bamako, Mali
4
ICRISAT Mali, Sorghum breeding; Bamako, Mali
2
The parasitic plant Striga hermonthica is a serious biologic constraint in the
production of sorghum [Sorghum bicolor (L.) Moench] and other cereals in subSaharan Africa, with yield reductions in infested fields commonly reaching 2080%. The impact on the host plant is especially severe under conditions of poor
soil fertility and drought, with a potential of total crop failure. Striga-resistant
and well adapted sorghum varieties are seen as an important part of an
integrated pest management to reduce yield loss as well as to avoid further
build-up of the striga- seed bank in infested fields. One known source of stable,
mechanical striga resistance in sorghum is the line N13 from India, which,
however, is poorly adapted to West African conditions. In a previous project
genomic regions (Quantitative Trait Loci, QTL) responsible for resistance have
been identified in a segregating population of N13 crossed with the susceptible
variety E-36-1. Five QTL were expressed consistently over two years and five
sites and explained between 12 and 30% of the observed genetic variance for
resistance. In a following cooperation between ICRISAT, IER, and the Univ. of
Hohenheim, two locally adapted, farmer-preferred sorghum varieties from Mali
were introgressed with up to four of the five resistance- QTL by markerassisted backcrossing. In this project, 32 of the resulting backcross-two lines
(BC2S3) were field-evaluated for their striga resistance under natural and
artificial striga infestation at three sites in Mali, West Africa, in 2009 and 2010.
Together with yield data and agronomic properties the number of emerged
striga plants per experimental plot was evaluated at regular intervals over the
cropping season as an integrative measure of disease severity. In parallel, the
presence/absence of the targeted genomic regions from N13 neighbouring the
QTL was tested in all lines using flanking SSR markers mapped to the vicinity
of the targeted QTLs. Preliminary analyses of the data show a resistance of the
best sorghum lines equal to or exceeding the resistance of the donor parent
N13. However, yield of BC2-lines was on average inferior to the recurrent
parents. A strong environmental influence on resistance between trial sites was
observed in the field experiments. The influence of the introgressed QTL and
their usefulness in breeding programs will be discussed.
Keywords: QTL, marker-assisted selection, environmental interaction
Contact: peter.muth@uni-hohenheim.de
67
Poster – Crop improvement
Application of TILLING to African understudied
crops
KORINNA ESFELD, SONIA PLAZA, REGULA SCHNEIDER, MORITZ JÖST,
ZERIHUN TADELE
University of Bern, Institute of Plant Sciences, Altenbergrain 21, 3013, Bern, Switzerland
Feeding the ever increasing population is one major challenge in the next
century. Resource-poor farmers and consumers in developing countries like in
Africa mostly depend on special staple crops (orphan crops) for their food
security, nutrition and income generation. These species like finger millet
(Eleusine coracana), tef (Eragrostis tef) or cassava (Manihot esculenta) are
locally important but are mainly unknown outside their countries. Understudied
crops are better adapted to unfavourable soil and climatic conditions and also
socio-economically accepted. However orphan crops have several limitations
and prominent bottlenecks are low productivity, poor in essential nutrients or
production of toxic substances. Since conventional breeding methods often do
not overcome these problems and transgenic methods can not be applied due
to negative public perception alternative molecular methods are needed from
which orphan crops may benefit. One promising technique is the nontransgenic and low-cost reverse genetic TILLING technique (Targeting Induced
Local Lesion IN Genomes), a method to identify single nucleotide changes in
the genes of choice. The procedure of TILLING comprises classical mutagenesis, development of a non-chimeric population, preparation of a germplasm stock, DNA extraction, sample pooling, population screening for induced
mutations as well as validation and evaluation of candidates. The technique
was first developed in the year 2000 for the model plant Arabidopsis thaliana
but successfully adopted to other species including orphan crops. Here, we
present the application of the TILLING technique to improve tef, one
understudied crop of Africa. Tef adapts to diverse climatic and soil conditions
and also tolerates many pests and diseases. In addition to its nutritional
advantages, seeds of tef are free of gluten. However, the productivity of tef is
limited mainly due to the prevalence of lodging. The plants have a tall and
tender stem which is susceptible to damage by wind and rain. Therefore,
developing lodging resistant semi-dwarf tef cultivars is one major goal of the
Tef TILLING Project. So far, screening of two genes involved in plant height,
DWARF11 (D11) and Tan-Ginbozu that encodes the ent-kaurene oxidase
(KO2), were done for more than 4000 M2 families of the ethyl methanesulfonate (EMS) treated tef cultivar DZ-Cr-37. Altogether up to 40 candidates were
found and confirmed by sequencing. 17 candidates were sown to evaluate their
performance and determine their use as semi-dwarf tef varieties.
Keywords: TILLING, understudied crops, Eragrostis tef
Contact: esfeld@ips.unibe.ch
68
Poster – Crop improvement
Improving drought tolerance and standing ability of
African under-studied crops: the case of tef
ZERIHUN TADELE, REGULA SCHNEIDER, KORINNA ESFELD, MORITZ JÖST, K
ASSEFA, SONIA PLAZA
University of Bern, Institute of Plant Sciences, Altenbergrain 21, CH-3013 Bern, Switzerland
Tef (Eragrostis tef) is a small grain cereal widely cultivated in the Horn of Africa
particularly in Ethiopia, where it is the number one in terms of acreage. The
crop is tolerant to many biotic and abiotic stresses prevalent in the region. In
general, tef plays a vital role in food security, nutrition, and income generation
to resource poor farmers. Despite its importance tef produces the lowest yield
compared to other cereals due mainly to the widespread use of landraces and
cultivars lacking desirable agronomic traits such as lodging resistance. Tef is
considered as understudied or orphan crop since it is largely neglected by the
world scientific community. Recently modern techniques such as Markerassisted Breeding and TILLING (Targeting Induced Local Lesions IN
Genomes) have been implemented to improve its agronomic performance.
TILLING is a non-transgenic and a high-throughput method used to improve
plants by identifying novel genetic variations in genes that affect traits of
choice. The technique has been successfully applied in major crops such as
maize and rice. We implement TILLING to tackle the major yield limiting factors
in tef production: drought and lodging. The tef TILLING population consists of
about 6000 M2 families. Three drought tolerant candidate mutants are being
tested for agronomic and physiological parameters related to drought
tolerance. Two semi-dwarf candidate lines obtained from the screening are
being evaluated in the field in Ethiopia. We have also initiated the Global Tef
Genome Sequencing Project and currently the sequencing is progressing at
various Next Generation Sequencing Platforms. The genome sequencing has
immediate applications in techniques such as TILLING since it elucidates
genomic sequences for the genes of interest.
Keywords: drought tolerance, under-studied crops, Eragrostis tef, TILLING,
genome sequencing
Contact: tadele@ips.unibe.ch
69
Poster – Crop improvement
Improvement strategies for dry tolerance on triticale
SALMANI ELHAM, HADDAD RAHEEM
International University of Gazvin, Department of Plant Biotechnology, Iran
The effects of single stress of silicon on plant growth, oxidative stress and
antioxidative enzymes were studied using two triticale (X Triticosecale)
genotypes differing in tolerance in an experiment. This plant was cultivated in
soil with 16ml silicon. We estimated growth, chlorophyllcontent, leaf
freshweight and yield. Results showed application of stress significantly
affected plant growth components such as fresh (FW) and dry weight (DW) of
triticale genotypes. dry stress decreased plant growth and caused oxidative
damage, as characterized by increased MDA and H2O2 contents. Under
silicon stress, the activities of Proline and antioxidative enzymes in leaves,
including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT),
were dramatically increased in plant tissues. A resistance tolerant genotype
had less oxidative damage than sensitive genotype. The extent of oxidative
damage induced by dry decrease of harvest. The combination of dry with
silicon caused a further decrease in plant growth, a decrease in and an
increase the activities of antioxidative enzymes. There was also a marked
difference between the two triticale genotypes in the extent of increased
antioxidative enzyme activity under dry and silicon stress.
Keywords: triticale, silicon stress, dry stress, antioxidat enzym
Contact: res.pina@yahoo.com
70
Poster – Crop improvement
Priming of NERICA and O. glaberrima rice seeds
enhanced germination and plant vigour
DANIEL ISAAC OLUDAYO
University of Agriculture, Plant Breeding/Seed Technology Dept., Abeokuta, Nigeria
New rice for Africa (NERICA) lines showed poor seed establishment
characteristics, a trait inherited from their West African native rice parent - O.
glaberrima. This constitutes a major limitation to acceptance and commercial
cultivation of the improved rice in Africa. In a preliminary trial, seed
germinability and plant vigour of 10 accessions of NERICA in response to
various priming duration treatments in aerated distilled water (hydro-priming)
and 20ppm KCl (halo-priming) were examined. In a second trial, germination
and vigour data were collected from 10 accessions of O. glaberrima seeds
which had undergone priming for different hours of hydro-priming with distilled
water and salt-priming with 20ppm KNO3 salt. In both trials, seeds that were
hydro-primed or salt-primed for 2, 24 and 48 hours germinated better than
control seed lots of all the NERICA and O. glaberrima varieties. Germination of
seeds was also optimal in the seeds treated for 48 hours in both studies. The
results showed efficacy of seed priming with water and/or salt as seed
enhancers for NERICA and O. glaberrima, indicating possible treatments for
seedling establishment and plant invigoration.
Keywords: Seed enhancement, Priming, West African rice
Contact: drdayodaniel@yahoo.com
71
Poster – Crop improvement
Improvement strategies for drought tolerance of rice
BIGLARY FATEMEH, HADAD RAHIM
Imam Khomeini of International University, department of plant biotechnology, Qazvin, Iran
Drought is the most important limiting factor for crop production and it is
becoming an increasingly severe problem in many regions of the world. Rice
(Oryza sativa L.) as a paddy field crop is particularly susceptible to water
stress. Drought is a world-spread problem seriously influencing grain
production and quality and with increasing population and global climate
change making the situation more serious. Silicon is one of the abundant
elements in soil and numerous studies have demonstrated that silicon elevates
tolerance of plants against environmental stresses. Simultaneously, the
variation in proline and total protein in leaves at different ages was determined.
In this study, effects of sodium silicate were investigated to analyze drought
induced oxidative stress on antioxidant enzymes (catalase (CAT), peroxidase
(POX) and proline content), total soluble protein and in two rice cultivars
namely Hashemi (tolerant) and Khazar (sensitive) at different developmental
stages. The results showed that antioxidant enzyme activities and osmolyte
contents were increased with the application of silicon in compared to the
control and drought treatments. Application of silicon improved the water status
of drought stress plants. Activities of antioxidant enzymes and osmolytes were
higher in the tolerant cultivar than sensitive. Also the experiment exhibited that
silicon effects are time dependent and its effects increased with lapse. Since
antioxidant enzymes were produced against reactive oxygen species (ROS)
induced by drought stress and osmolyte accumulation occurred in response to
stress to protect plant tissues against oxidative stress. It might be concluded
that silicon increased drought tolerance in both cultivars. Therefore, exogenous
silicon should be applied to reach a higher efficiency of plant production.
Keywords: Rice, drought, CAT, POX, antioxidant enzyme
Contact: fatemeh_biglaryznu2005@yahoo.com
72
Poster – Crop improvement
Performance of elite Faba Bean (Vicia faba L.)
varieties at two different altitudes on Nitisols of
southwestern Ethiopia
AMSALU NEBIYU1, JAN DIELS2, PASCAL BOECKX3
1
College of Agriculture and Veterinary Medicine, Jimma University, Ethiopia
Faculty of Biosciences Engineering, KU Leuven, Belgium
3
Laboratory of Applied Physical Chemistry - ISOFYS, Faculty of Biosciences Engineering, Ghent
University, Belgium
2
A field experiment has been carried out involving fifteen elite faba bean
varieties and a local variety in RCBD with three replicates at Jimma and Dedo,
southwestern Ethiopia, in 2007/2008 cropping season. The aim was to
evaluate varieties for adaptation and grain yield performance allowing selection
and promote adaptable varieties for further integrated soil fertility management
practices. Combined analysis of variance showed that the effect of location was
highly significant (P<0.01) on plant height, pods per plant, seeds per pod and
grain yield per hectare. The main effect of variety was highly significant on
plant height, 1000 seeds weight and grain yield per hectare. The interaction
effect of location and variety was also highly significant (P<0.01) on 1000
seeds weight and grain yield. The highest grain yield at Dedo and Jimma was
-1
-1
obtained with the local variety (3.1 t ha ) and Walki (1.9 t ha ), respectively.
-1
Average grain yield for Dedo and Jimma was 2.3 and 1.2 t ha , respectively.
Out of the total variation observed for grain yield, a relatively large variation
(40.1%) was accounted for by the location. The remaining was due to the
interaction effect (25.6%), varieties (15.7%) and the block and error term
together (18.6%). No variation was observed in nodule number for variety,
location or their interaction. Correlation analysis among yield and yield
components indicated that grain yield was highly significantly and positively
(P<0.01) correlated with plant height and seeds per pod at Dedo and with
plant height and pods per plant at Jimma. The present study highlighted that
most varieties showed good adaptation and grain yield performance
predominantly at Dedo and pointed out to the presence of potential faba bean
varieties for production in the region and similar areas. However, quantifying
the magnitude of nitrogen fixation and balance is required to evaluate the
potential of faba bean to contribute to long-term crop production stability and
effects in legume-cereal rotation.
Keywords: adaptation, faba bean, grain yield, southwestern Ethiopia
Contact Address: anebiy@yahoo.com
73
Poster – Crop improvement
Genotype x Environment interaction of Bambara
groundnut grown in Soudan and Sahel regions of
Burkina
MAHAMA OUEDRAOGO, HALIDOU GUIGMA, JACQUES SAWADOGO,
MOHAMED OUEDRAOGO
INERA, Institute, Burkina Faso
The yield of any crop is the result of interactions between its genetic potential,
agricultural practices provided during its growing and the agro ecological
conditions (soil structure, texture, fertility, temperature, sunlight, water
availability, etc?). In subsistence agriculture and in particular in semi arid region
like Burkina Faso, farmers have fair control of agro ecological conditions.
Mainly, it’s a rain fed agriculture. But, in the Soudan agro ecological zone
(annual rainfall ranges between 900 and 1100 mm), water supply is not a big
constraint in comparison to Sahel agro ecological zone (300 to 600 mm).
Bambara groundnut is an underutilized African native legume which is grown
mainly by female farmers from the arid Sahel area to Soudan agro ecological
area in Burkina Fas. It is a complete food as it contains 54.5 - 69.3 % of
carbohydrates, 17 - 24.6 % of protein, 5.3 - 7.8 % of fat and 367 - 414 Kcal
energy per 100g. Even if, average yield of Bambara groundnut in Burkina Faso
is around 750 kg per ha, there is a wide range of yield according to rain fall and
agro system patterns. In the aim to provide accurate agricultural practices in
complement to the breeding program of Bambara groundnut in a climate
change conditions characterized in Burkina Faso by drought and flooding, an
experiment on interaction of genotype x environment was implanted in both
Sahel and Soudan agro ecological zones. A completed randomized block
design with four replications was implemented in the two regions. Data were
collected on fifteen parameters including stomatal conductance and soil water
content.
Keywords: Bambara groundnut, Environment, Genotype
Contact: mahama.ouedraogo@fulbrightmail.org
74
Poster – Traits for ideotypes, Modelling
Intra-annual genotypic patterns of growth and water
use of irrigated rice in the Sahel
SABINE STÜRZ1, FOLKARD ASCH1, ABDOULAYE SOW2, BERTRAND MULLER3,
BABOUCARR MANNEH 2
1
Department of Plant Production and Agroecology in the Tropics and Subtropics, University of
Hohenheim, Germany
2
AfricaRice, St. Louis, Senegal
3
CIRAD, St. Louis, Senegal
With an increasing world population, the demand for rice as one of the most
important staple crops is growing. Rice production can be increased either by
intensification of existing or by exploitation of new and less favourable land
resources. At the same time, rice production is confronted with climate change
and increases in temperatures as well as more frequently occurring weather
extremes are expected. In order to overcome the challenge of climate change
as well as an increasing demand for rice, locally adapted varieties are needed,
which are able to meet the given climatic conditions.
Rice production in the Senegal River Valley strongly depends on intra-annual
climatic variation with a hot and dry period from March to July, a short wet
season from August to October, and a cold and dry period from November to
February. During the hot season, heat sterility as well as high water losses due
to extreme vapor pressure deficits are common. The cold season is
characterized by low development rates and high yield losses due to cold
sterility. These variable conditions are ideal for studying genotype-byenvironment interactions in order to assess genotypic traits with regard to their
suitability to specific environments.
For the ongoing study, 10 contrasting genotypes were selected representing
the large variation in the global gene pool in terms of duration, water use, and
heat and cold tolerance. In bi-monthly planting dates, irrigation water input,
evapotranspiration, plant development and yield were observed at 2 climatically
different sites under flooded and non-flooded conditions in order to identify
genotypic traits supporting water limited rice production as well as stable high
yields under rather unfavourable thermal conditions. Varietal responses in
terms of water use and yield will be presented and the related traits and their
beneficial characteristics for specifically targeted environments discussed.
Keywords: Irrigated rice, temperature stress, water use efficiency, climate
change
Contact: sabine.stuerz@uni-hohenheim.de
75
Poster – Traits for ideotypes, Modelling
Phenological responses of irrigated rice in the Sahel
SABINE STÜRZ1, FOLKARD ASCH1, ABDOULAYE SOW2, BERTRAND MULLER3,
MICHAEL DINGKUHN4, BABOUCARR MANNEH2
1
Department of Plant Production and Agroecology in the Tropics and Subtropics, University of
Hohenheim, Germany
2
AfricaRice, St. Louis, Senegal
3
CIRAD, St. Louis, Senegal
4
CIRAD, Montpellier, France
Worldwide rising temperatures are already being observed and are expected to
increase within the next decades. In the Sahel cool periods cause yield losses
due to spikelet sterility in late sown rice and thus Sahelian rice production
systems might benefit from increasing temperatures. Higher temperatures
during the vegetative phase will lead to shortened crop duration and during the
reproductive phase higher temperatures during cool periods might reduce
sterility. For the hot periods negative effects on biomass production and
increased sterility due to heat stress are expected. The complexity of those
phenomena requires well validated crop models able to precisely assess
development and yield according to genotype and climate for predictive
conclusions and adaptive decisions (choice of genotype, sowing date) under
changing climatic conditions.
In the early 90s for a wide range of germplasm phenology was observed and
yield components were determined in staggered planting dates at AfriceRice’s
Sahel station in Ndiaye, Senegal. Based on this, a model (RIDEV) was
developed by Dingkuhn et al. (1995) to estimate duration and sterility for
multiple rice varieties in the Sahel as a function of sowing date. Until now, it
has been used by the operational services. However, differences between crop
cycles observed in farmers’ fields and assessed by RIDEV have been reported.
This could be explained either by model deficiencies, varietal evolution and/or
climatic changes.
Presently in Ndiaye (coastal-semi-arid) and Fanaye (continental-semi-arid), 10
strongly contrasting rice varieties are grown year-around in monthly-staggered
planting dates in order to determine duration, leaf appearance rate and sterility
under current climatic conditions. Those varieties include some of the formerly
observed genotypes as well as heat- and cold-tolerant reference varieties.
Results will be used to improve RIDEV thus allowing for predictions of crop
responses to climate change. Preliminary results with a focus on derivation of
photo-thermal constants will be presented for the first completed year and
compared to results from former years.
Keywords: modelling, RIDEV, Climate Change
Contact: sabine.stuerz@uni-hohenheim.de
76
Poster – Traits for ideotypes, Modelling
Climatic Effects on the Yield of Upland Rice Grown
Along an Altitude Gradient in Madagascar
SUCHIT SHRESTHA 1, FOLKARD ASCH1, ALAIN RAMANANTSOANIRINA2, JULIE
DUSSERRE3
1
University of Hohenheim, Department of Plant Production and Agroecology in the Tropics and
Subtropics, Stuttgart, Germany
2
FoFiFa, Madagascar
3
CIRAD, France
Development of upland rice can supplement to lowland rice as the pressure is
increasing on irrigated land. In Madagascar, rice is cultivated on 1.3 M ha of
which 29% are upland rice, growing from the coastal area up to the higher
altitude. High altitude rice cultivation is constraint by a short vegetation period
due to low temperatures and thus by the time the crop needs to complete its
cycle. Climate change is assumed to result in a rise in mean temperatures of
2–5 degrees depending on the simulation scenario. Thus, rice cropping in
higher altitudes may become more favorable as long as precipitation is not a
limiting factor. The RISOCAS project of the University of Hohenheim for
developing rice crop adaptation strategies for climate change in vulnerable
environments has selected three different altitude gradient locations
(Andranomanelatra 1625 m, Ivory 965m and Ankepaka 25m asl)
in
Madagascar for the upland rice field experiments. Mini Rice Gardens were
designed for 10 contrasting rice genotypes with 5 monthly planting dates on
three locations resulting in 15 different photo-thermal environments. At all sites,
genotypic and planting date responses were studied by closely observing the
time and temperature requirements to panicle initiation, booting, heading,
flowering, and physiological maturity. In addition grain yield and yield
components and spikelet sterility were observed. Temperature effects on
sterility are discussed in order to judge the agronomic fit of a potential upland
rice ideotype for higher altitude cropping in a changing climate.
Keywords: Climate change adaptation, temperature, yield, sterility, RISOCAS
Contact: suchitps@uni-hohenheim.de
77
Poster – Traits for ideotypes, Modelling
Photochemical Reflectance Index and SPAD values
for Leaf Nitrogen of Rice
SUCHIT SHRESTHA, HOLGER BRUECK, FOLKARD ASCH
University of Hohenheim, Department of Crop Production and Agroecology in the Tropics and
Subtropics, Section: Crop Waterstress Management, Stuttgart, Germany
Plants are often subjected to abiotic stresses. Of the stressors, nitrogen
deficiency is important in many natural vegetations and agricultural production
systems. Chlorophyll Meter (SPAD) is widely used in crops like wheat and rice.
An alternative approach of non-destructive measurements is based on spectral
reflectance of vegetation surfaces like photochemical reflectance index (PRI), a
normalized difference index using two narrow reflectance bands at wavelength
of 531 nm and 570 nm, which has been developed as a quantitative measure
of leaf reflectance. This study is indented to compare measurements with
PlantPen PRI-200 handheld PRI device with Minolta SPAD-502 chlorophyll
meter readings, and chlorophyll fluorescence and gas exchange parameters
using GFS-3000 (Heinz Walz GmbH, Germany) of rice plants.
Cold-tolerant rice cultivar Chomrong was grown in a hydroponic systems using
Yoshida nutrient solution of pH 5.5 with different N levels (0.18, 0.36, 0.71,
1.43, 2.86, 4.28, 5.71 mM N) in a greenhouse at the University of Hohenheim,
Germany, from August 2009 to October 2009. After 41 and 57 days in Yoshida
solution, fully developed youngest leaves were measured and harvested.
SPAD and PRI values increased with increasing N supply explain correlation
between SPAD and PRI values. Non-photochemical quenching parameters qN
and NPQ were significantly affected by N levels. PRI values correlate
negatively with NPQ. Maximum assimilation (Amax) positively correlates with
N-levels.
Keywords: Photochemical Reflectance Index, Chlorophyll, Non-Photochemical
Quenching, Rice
Contact: suchitps@uni-hohenheim.de
78
Poster – Traits for ideotypes, Modelling
Climate change and future rice production in Ghana:
Farmers’ perceptions and experimental evidence
F.O.TABI 1, S.G.K. ADIKU2, K. OFORI 3, M. OMOKO 3
1
University of Dschang, Department of Soil Science, Dschang, Cameroon
University of Ghana, Department of Soil Science2, Crop Science3, Legon, Ghana
2, 3
Rice cropping systems are found in a number of ecologies, from coastal
swamps which may be affected by sea level rice and intrusion of salt water to
water-scarce upland ecologies. Presently, rice demand far exceeds production
and it is expected that climate change (CC) would increase this deficit. The
views of small-scale farmers when coupled with scientific experimentation
would provide suitable adaptation options to reduce the impact of CC on
society. How farmers perceive CC, how they have been coping and their future
worries coupled with scientific evidence on CC is important in shaping
adaptation strategies. However, the link between farmer’s perception and
scientific evidence in developing suitable adaptations has often been weak.
This study was undertaken as a basis to strengthen this link with the aim of
identifying strategies to direct future rice production in Ghana. Four study sites
were selected in the Volta region of Ghana. The research methods included
structured questionnaires to capture farmers perceptions, agronomic
experiments and the CERES-Rice, Cowpea and Soybean models of the
Decision Support System for Agrotechnology Transfer (DSSAT 4.2) to evaluate
soil management options in rainfed lowland rice cropping system under current
and future (downscaled GCMs) climates. Rice farmers perceive CC as less and
irregular rainfall, delayed onsets of rains, increasing frequency of extreme
events, increasing weed population and frequency of crop failure. Although
high yielding rice varieties are available, farmers prefer a local variety, Viwonor
because of its good taste, ability to meet the needs of the household from a
smaller quantity and other cultural roles it performs. Farmers require
technologies that would reduce the impact of anticipated decrease in rainfall on
rice (year 2046-2065): decrease of 2 - 23% = 21.8 - 312.7 mm, with 78 - 85%
of this decrease between June to September. A shift in peak rainfall from June
to July is expected. Cowpea/soybean - rice rotation would be an option to
utilize early rains and build soil fertility for increased and stable rice yield
through biomass incorporation. A national breeding program which seeks to
increase the yield potential and drought tolerance of Viwonor, while maintaining
farmer’s preference characteristics is advocated. Additional re-search is
required to establish suitable planting dates for efficient use of limited rainfall
and to avoid moisture stress at critical growth and reproductive stages.
Keywords: Rice, climate change, DSSAT, Global circulation models, cropping
systems
Contact: obenft@yahoo.com
79
Poster – Traits for ideotypes, Modelling
Assessing and setting a coping mechanism for the
impact of climate variability on severity of rust
diseases and wheat production Over Arsi Highlands,
Ethiopia
ESHETU DEBELE, SISAY1, KORECHA DADI, DIRIBA2, BEDADA GIRMA3,
1
Arba Minch University; 2 National Meteorological Agency; 3 Kulumsa Agricultural Research Center
El Nino/Southern oscillation (ENSO) is one of the most important and bestcharacterized mechanisms of global climatic variations. It has tremendous
impacts on local, regional and global climatic conditions. Tropical agricultural
practices are very sensitive to climatic anomalies that jeopardize the
performance of crop production by generating water stress or excess during
various developmental stages. The Arsi highland is highly influenced by global
circulation patterns that govern the local climate. Among crop varieties that
grow over the Arsi highland, number of wheat cultivars is widely cultivated both
at individual farm levels and mechanized state farmers. Previous studies have
revealed that these cultivars are highly sensitive to seasonal rains, temperature
and relative humidity occurring during the sowing, germination, vegetative,
flowering, and seed-filling and harvesting periods. We examined the coherence
or lag-time relationships between local climate variables and teleconnection
parameters such as ENSO and other prominent atmospheric phenomena.
Besides, this study is trying to see whether there exist any linear association
between the severity of rust diseases and local climatic variables that affect the
overall performance of wheat crop and climatic parameters. The study results
revealed that ENSO has played a great role in modulating the seasonal rainfall
over the Arsi highlands, which in turn influences wheat crop performance. In
particular, it has induced rust diseases over the regions that significantly affect
the quality and quantity of wheat yield. We propose that skillful early warning
can be well practiced by acquiring appropriate lead-time climate-based
forecasting of on the possible occurrence of both climates and diseases on
varieties of wheat crops across the Arsi highland. On the basis of our findings it
will be possible to identify less climatic sensitive wheat cultivars that may give
high productivity over the study region. Thus the choice of wheat cultivars such
as Galama, Enkoy, Kb295-4a and Israel that could be highly resistant to the
rust diseases and climate variability should be selected and distributed to the
farmers Whereas over Kulumsa, Arsi Negele and Asasa regions, it should be
better to sow wheat varieties like Galama, Enkoy, Tussie, Abola, Kb-290 and
ET-13A, which are highly resistant to yellow rust diseases infection and climate
anomalies.
Keywords: ENSO, Climate Variability, Rust Diseases, Modeling, Yield Fluctuation
Contact: dkorecha@yahoo.com
80