Cotton Management Options
TAWC Water College
Craig W. Bednarz – Principal Agronomist
Forward-Looking Statements
This presentation may contain forward-looking statements based on current
assumptions and forecasts made by Bayer Group or subgroup management.
Various known and unknown risks, uncertainties and other factors could lead to
material differences between the actual future results, financial situation,
development or performance of the company and the estimates given here.
These factors include those discussed in Bayer’s public reports which are
available on the Bayer website at www.bayer.com.
The company assumes no liability whatsoever to update these forward-looking
statements or to conform them to future events or developments.
Page 2 • TAWC Water College • January 2016
Agenda
Focus on Drought Mitigation
Breeding
Agronomic Services
Page 3 • TAWC Water College • January 2016
Drought
The absence of rainfall for a period of time long enough to result in depletion of
soil water and injury to plants.
The length of time without precipitation necessary to cause injury depends on the
kind of plant, it’s growth stage, the soil water holding capacity and the rate of
evapotranspiration.
• Severity is determined by intensity and duration of drought.
• Can not predict timing or severity of drought (currently).
• “What kind of drought are we breeding for?”
• Can not be ambiguous.
• Must have very specific breeding objectives.
Page 4 • TAWC Water College • January 2016
How water occurs in soils
Page 5 • TAWC Water College • January 2016
FAO Penman-Monteith ETo
Page 6 • TAWC Water College • January 2016
How do plants respond to drought?
Crops can not avoid random drought events characteristic of most environments.
Adaptations that increase their tolerance to drought.
• Dehydration postponement.
• Dehydration tolerance.
Page 7 • TAWC Water College • January 2016
Dehydration Postponement
Dehydration is postponed by
morphological or physiological
characteristics that either reduce water
loss by transpiration or increase water
absorption.
Root systems:
• Deep and wide spreading.
• Tap rooted vs. fibrous rooted crops.
• Cultivars may differ in rooting
characteristics.
• Earliness may impact rooting.
• Soil type.
• Crop management.
• Interplant competition.
• Insect and disease control.
Page 8 • TAWC Water College • January 2016
Increased Water Absorption
Disadvantage:
• Extensive root system may remove too much water, resulting in not enough
water to mature the crop.
• Where crops are irrigated or receive sufficient rainfall, extensive root systems
may not be necessary and are wasteful.
• Growth and maintenance respiration costs.
Page 9 • TAWC Water College • January 2016
Question
Would it be desirable to have cotton cultivars in the High Plains that possess
deeper and more extensive rooting systems?
• Carbon allocation burden?
• Is there sufficient genetic variance for improvement?
• Can we measure it?
• How do we select for it?
• Would it result in more complete or efficient soil water uptake?
• What if we could extract an additional 2-3% soil water (volume basis)?
• At a rooting depth of 40 inches this would be ~ 1.0” of water.
Page 10 • TAWC Water College • January 2016
Reduced Transpiration
Leaf Adaptations:
• Change leaf orientation – reduced absorption
• Leaf rolling – reduced absorption
• Leaf wilting – reduced absorption
• Leaf pubescence – increased reflectance
• Leaf cuticle – reduce transpiration
• Leaf shedding – reduced absorption
• Stomatal movement – reduced transpiration
Page 11 • TAWC Water College • January 2016
Reduced water loss by energy
shedding
Page 12 • TAWC Water College • January 2016
Reduced Transpiration
Stomata adaptations:
• Xerophytes (plants adapted to
growing in dry conditions) have high
rates of transpiration in moist soils,
but close stomata as the soil dries.
• Mesophytes (plants adapted to
growing with moderate moisture)
such as sorghum have shown
different levels of drought tolerance,
which has been attributed to different
levels of stomatal control.
Page 13 • TAWC Water College • January 2016
Leaf Transpiration vs. Photosynthesis
Photosynthesis (umol m-2 sec-1)
Sorghum, Cotton and Castor
Quaker Farm
080608
50
40
Sorghum
Coefficients:
b[0]=2.5245008139
b[1]=2.8433466669
r ²=0.9460048339
Cotton
Coefficients:
b[0]=1.1748950766
b[1]=1.9842508358
r ²=0.9894598983
Castor
Coefficients:
b[0]=0.7832777271
b[1]=1.7468533781
r ²=0.9867669405
30
20
10
0
0
5
10
15
20
Transpiration (mmol m-2 sec-1)
Page 14 • TAWC Water College • January 2016
25
High Throughput Phenotyping
Which one?
• High Temp.?
• Low Temp.?
• Intermediate?
Page 15 • TAWC Water College • January 2016
High Throughput Phenotyping?
Page 16 • TAWC Water College • January 2016
2015 Irrigation x Variety CAP Trials
AG CARES - Lamesa
Four replicates
Drip Irrigation
In-season Rainfall ~15”
Irrigation
 Dry – 0”
 Low – 4.1”
 Medium –7.4”
 High – 9.9”
Lbs/A
567
712
1,360
1,236
1,075
Conducted by Dr. Wayne Keeling, Texas AgriLife Research
1,365
1,155
1,054
1,390
Irrigation x Variety CAP Trial
689
1,093
1,083
1,445
Low
712
1,165
1,107
Med
634
1,504
1,256
1,143
1,504
1,273
1,070
1,086
1,570
1,613
1,546
1,367
1,286
1,130
1,297
1,047
High
709
677
652
606
615
1,635
1800
1600
1400
1200
1000
800
600
400
200
0
1,317
1,118
2015 Lamesa AG CARES
q
Lint Yield
Dry
Energy Balance:
Horizontal leaf, full sunlight, sea level
Energy in:
605 (SW) + 624 (IR) = 1229 W m-2
Energy out:
1229 – 859 (eIR) – 190 (sensible) – 180 (latent)= 0 W m-2
Approximately 98% of the water used by a crop is to deal with ~15% of the
energy it absorbs.
Improvements in WUE can be made from reducing the % of E dissipated by
latent heat exchange.
Physiochemical and Environmental Plant Physiology by P.S. Nobel, Chapter 7
Page 19 • TAWC Water College • January 2016
Final Thoughts
Adaptation (improved drought tolerance) – heritable modifications in structures
and processes that increase (or decrease) the probability of an organism
surviving in a given environment.
Page 20 • TAWC Water College • January 2016
Final Thoughts
Can we effectively measure drought tolerance?
• Genetic differences may be small.
• Differences in drought may be huge.
• Unexplained field variance more problematic in non-irrigated or limited
irrigated tests.
Page 21 • TAWC Water College • January 2016
Final Thoughts
Do we have sufficient genetic diversity in our elite germplasm for drought
tolerance improvement?
• During domestication alleles that are useful in managed cropping system were
advanced while alleles that are useful for survival in the wild may have been
discarded.
Page 22 • TAWC Water College • January 2016
Thank you!