STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
There are 12 centres of diversity / megadiversity. India is one of the 12 megadiversity regions of the world
with 8% of global genetic resource and some 45000 species of plants. Vailov (1926) proposed that different
crop plants originated in different areas where their wild relatives are present and genetic diversity is
maximum with temperature fluctuations and UV radiation’s Vavilov proposed 8 centres. Australia is the
12th centre. The eight main geographic centres of centres of origin of cultivated plants with their natives are
as follows :
1. The Chinese centre of origin : This is the largest and oldest independent centre of cultivated plants.
2. The Indian centre of origin :
(i) Main Centre : It includes Assam and Burma.
(ii) Indo–Malayan Centre : It includes Indo–China and Malaya.
3. Central Asiatic centre of origin : It includes Punjab, North–West Frontier Provinces, Afghanistan,
Tajakistan and Uzbekistan.
4. Near Eastern centre of origin : It includes Asia Minor, Transassia and Iron.
5. Mediterranean centre of origin : It Includes border of Mediterranean Sea.
6. The Abyssinian centre of origin : It includes Ethiopia and Somalia.
7. South Mexican and Central American centre of origin
8. South American centre of origin :
(i) The Peruvian–Ecuadorian–Bolivian Centre
(ii) The Chile Centre
(iii)
The Brazilian–Paraguayan Centre
Primary Crop
It is a crop which came under domestication from the very beginning. e.g, Wheat
Secondary Crop
There are originally the wild relation of primary crop which was domesticated when primary crop failed.
If the collected germ plasm belongs to the same country, it is known as Indigenous collection but it the
collected germ plasm belongs to foreign origin, it is known as Exotic collection.
Plant Breeding
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When genotype of an organism is modified to make that organism more useful to humans, the process
is called breeding. The branch of science concerned with improvement of varieties of crops is called
Plant breeding.
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Aims and objectives of plant breeding are :–
(a) To improve the quality of the crops.
(b) To improve resistance to drought, frost, disease and salinity.
(c) To get higher yield.
(d) To introduce other useful traits.
The applied branch of Botany, which deals with improvement of agricultural crop plants is called Plant
breeding.
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Important Plant Breeders
(i) N.I. Vavilov : Famous Russian plant breeder, who gave centres of origin of cultivated plants.
(ii) N.E. Borlaug : Famous Mexican plant breeder, who was awarded Nobel Peace Prize (1970) for
developing high yielding dwarf wheat varieties like Sonora–64, Lerma rojo–64, etc. He is known as
‘Father of green revolution’.
Indian Plant Breeders
(i) Sir T.S. Venkatraman : Pioneer Indian plant breeder famous for sugar cane improvement.
(ii) Dr. B.P. Pal : Famous wheat breeder, who produced many NP wheat varieties.
(iii) Dr. M.S. Swaminathan : He is pioneer mutation breeder. He has produced Sharbati Sonora variety of
wheat by mutation, which is responsible for green revolution in India. Dr. Swaminathan is called ‘Father
of green revolution in India’.
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
A. Steps in plant breeding
Plant Introduction
(i) The process of introducing plants with specific characters from their area of origin to a new area (where
they may be used directly or indirectly) is called plant introduction.
(ii) If plants are introduced from foreign country then it is called exotic collection (EC) but if brought from
same country, then it is called indigenous collection (IC).
(iii) It is brought about mainly by the movement of man.
(iv) It is very easy, effective and quickest method of plant breeding.
(v) Introduced plants may be used directly for cultivation (Primary introduction) ; or may be used after
subjecting to selection/hybridization (Secondary introduction).
(vi) National Bureau of Plant Genetic Resources (NBPGR), New Delhi keeps control on plant introduction.
Procedure of plant introduction
It consists of the following steps :–
(i) Procurement of germplasm – New plants are introduced in the form of seeds, cuttings, tubers,
bulbs, runners, suckers, seedlings, etc.
(ii) Quarantine checks – All the introduced material is thoroughly inspected for contamination with weeds,
diseases and insect pests.
Plant quarantine is meant for preventing introduction of exotic pests, weeds and disease in the country
under Destructive Insects and Pests (DIP) Act, 1914. Twenty six plant quarantine and fumigation station
have been set up in India.
(iii) Cataloguing – The material is given an entry number and information regarding the name of species,
variety, place of origin, adaptation are recorded.
(iv) Evaluation – Performance with respect to disease resistance etc. are checked.
(v) Acclimatisation – The adjustment of newly introduced plant to new or changed environment is called
acclimatisation.
(vi) Multiplication and distribution – The introduced material/plants are multiplied and finally distributed.
Organisations involved in plant introduction
(i) National Bureau of Plant Genetic Resources (NBPGR), New Delhi (Estd. 1976) helps in plant introduction
in India.
(ii) Forest Research Institute (FRI), Dehradun helps in introduction of forest trees in India.
(iii) Central Rice Research Institute (CRRI), Cuttack  Rice.
(iv) Central Potato Research ,Institute (CPRI) Shimla  Potato.
(v) Sugarcane Breeding Research Institute, Coimbatore  Sugarcane.
(vi) Botanical Survey of India  Aromatic and medicinal plants (Headquarter of BSI  Calcutta)
(vii) Central Plantation Research Institute, Kaisargode  Coconut.
(viii) International Crops Research Institute for Semi – Arid Tropics (ICRISAT), Near Hyderabad  Groundnut,
Gram etc.
B. Selection
It refers to selecting an economic an economic plant having desirable characters from a given population of
plants based on its phenotypic characteristics. Plant selection can be practised in three ways:
i)
Mass Selections:
It is practised in naturally cross-pollinated crops e.g., maize. The seeds of selected plants are sown in the
same field to allow natural cross-pollination. The plants are selected from this field by eliminating the
undesirable ones and saving the best. The seeds of selected plants are multiplied on large numbers and
supplied to the farmers.
ii) Pure Line Selection:
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It is practised in naturally self-pollinated crops
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
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A population of homozygous plants raised from a single homozygous plant or from a plant which
has been rendered homozygous by repeated selfing, is called pure line all the plants in a pure line
have identical genotypes .
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Pure line selection is better as compared to mass selection because here the selected plants
retain their desirable characters for several years. e.g., PV-18, HUW-468, Kalyan Sonavar or
wheat
iii) Clonal Selection :
It is practised in vegetatively propagated plants e.g., Kufri Sated var. or Potato
C. Hybridisation
It is the most common method of creating genetic variation. This technique involves crossing two plants
differing in genotypes to get a new synthetic one possessing the combination of good qualities of the
parental plants. The main steps followed during hybridisation are:
i) Selection and isolation of parents: The plant breeder selects the plants that he will use as male and
female plants. The crossing is often performed in a green house under controlled conditions. The male
plants are kept ready so that their flowering coincides with that of female plants.
ii) Emasculation: If the two plants (parents) have bisexual flowers then their anthers are carefully removed,
this is called emasculation. The prevents self-pollination in these flowers.
iii) Bagging : The flowers on female plants are kept in isolation by enclosing them in bags (made of paper,
polythene or muslin cloth) so that no foreign pollen may fall on stigma. This process is called bagging.
 Pollination. With the maturation of stigma, the pollen grains from the mature made plants are
dusted upon the stigma of the female flowers after removing the bags. The bags are replaced
immediately after the pollination. The seeds produced by these flowers of the female parent are the
hybrids or F1 seeds.
 The crosses between different varieties of the same species constitute the intervarietal
crosses or interspecific hybridisation. Such types of crosses have been of greatest importance in
the improvement of vegetables and wheat crops. Ganga and Ranjit variety of maize is the result of
intervavietal cross while rice variety ADT-37 (oryzae japouica x O-indices) are the result of interspecific
crops.
 A cross between two different genera is called intergeneric cross. A classical example of
intergeneric hybridisation is that of wheat-rye (Triticale)
Hybrid Vigour or Heterosis. It refers to the exhibition of superiority of the hybrid over both of its parents in
one or more traits.
Inbreeding Depression. When two related individuals of a species which have common ancestry are mated
together, it is known as inbreeding. The process of self-pollination (selfing) in case of cross-pollinated
plants is called inbreeding. The close inbreeding normally reduce fertility and productivity in cross-pollinated
plants and all animal species. The phenomenon is known as inbreeding depression.
D. Mutation Breeding
It can arise due to a change in any of the following (i) chromosomes structure, (ii) chromosome number
and (iii) base sequence of the gene. Mutations may occur in nature at a very low rate and are called
spontaneous mutations or may be induced artificially and are called induced mutations. The agents which
cause mutations are called mutagens or high energy rays. The chemical mutagens like nitrous acid,
ethylmethane sulphonate (EMS), nitromethyl urea and nitrosoethyl urea, mustard gas and ionising, radiations
like UV rays have been widely used to induce useful mutations Some examples of crop improvement by
mutations breeding are:
Wheat
- Sharbati Sonora, Lermarozo
Rice
- Reimei, Atomita-2, Jagannalti
Barley
- Erectorides and Eceriferum
Castor
- Aruna
Gram
- Kiran
Groundnut
- TG1 & TG3
Cotton
- Indore - 2
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
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Peppermint (Mentha piperata), Todd’s Mitcham variety are of high oil content and disease resistant in
nature.
E. Polyploidy
The polyploid individuals are of following two types:
(i) Autopolyploid : An autopolyploid individual contains more than two sets of single e.g., autotriploid
(AAA), autotetraploid (AAAA). There are few cases where an autopolyploid has succeeded as a variety,
e.g, an autotriploid variety of tea in India. The other examples of triploids include seedless banana,
watermelon, apple, pear etc.
Doob grass (cynodon dactylon) is autotriploid and Barseem (Trifolium alexandrium) is autotetraploid.
Autotriploids are sexually sterile and propagated vegetatively e.g., sugarbeat, doob grass while
autotetraploids are sexually fertile e.g., apple, grapes, potato, etc.
(ii) Allopolyploid : They develop due to hybridisation between tow distinct species followed by doubling
of ;chromosomes by colchicine. Allotetraploid (AABB) is the common type. More than half of the
cultivated plants are allopolyploids such as wheat, cotton oats, sugarcane, tobacco and plums. Common
bread wheat (Triticum aestivum) is one of the best example) is one of the best example of allopolyploidy.
Artificially a developed allopolyploid is Triticale which is the first man-made crop derived by crossing
wheat (Triticum) and rye (Secale). This new cereal gives better bread and is well adopted in sandy soil
where normally wheat cannot by grown. Example 1: Origin of bread wheat.
Triticum boeoticum (wild Einkorn)
(T. aegilopoides)
2n = 14, AA
Cultivated Einkorn
(2n = 14)
Aegilops speitoides
(2n = 14, BB)
Sterile Hybrid
Chromosome doubling
Mutation
Durum wheat
(T. durum)
Tetraploid Emmer wehat
(T. turgidum) 2n = 28, AABB
Aegilops speitoides
(2n = 14, BB)
Sterile Hybrid
Hexaploid Bread wheat
(T. aestivum)
AABBDD (2n = 6x = 42
Origin of Bread and Durum Wheat
Example 2 : Origin of Raphanobrassica
Raphanus sativus (Radish)
X
Brassica oleracea (Cabbage)
RR = 18
BB = 18
F1 hybrid (sterile)
R + B = 18
Doubling of chromosomes
Raphanobrassica
RR + BB = 36
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
Testing for Disease Resistance and Selection.
For testing the proper incorporation of the disease resistance, the improved plants are grown alongwith
susceptible ones under conditions in which the susceptible plants develop disease. The pathogen is allowed
to freely infect the plants in heavy doses. The disease resistant plants are identified and selected for
multiplication.
Some Common Disease Resist Varieties
Crop
Variety
Resistance to Diseases
Wheat
Himgiri
Leaf and stripe rust, Hill Blunt
Brassica
Pusa Swarim (Karan Rai)
White rust
Cauliflower
Pusa Shubhra, Pusa Snow ball K-I
Black rot and Curl blight black rot.
Cowpea
Pusa Komal
Bacterial blight
Chilly
Pusa Sadabahar
Chill mosaic virus, Tobacco mosaic
virus and Leaf curl.
Plant Breeding for Developing Resistance to insect pests
A number of insects and other pests feed on crop plants. Damage to crop plants is often tremendous.
Insecticides or pesticides are useful to a minor extent as insects develop resistance to them very soon. So
newer and more potent insecticides are required all the time. They make agricultural operations costlier.
The environment as well as the crop yield becomes polluted and harmful to humans and other living forms.
Therefore, it is important that insect resistance is incorporated in crop varieties.
Germplasm consisting of all present day, old and local varieties as well as wild relative are screened for
desired trails that can give protection from pests. Plants with desired traits are incorporated in breeding
programmes for new high yielding varieties. They are tested for insect resistance and then selected for
cultivation. Through genetic engineering, cry gene of Bacillus thuringiensis has been incorporated in some
crop plants e.g., Bt Cotton.
Some varieties having Insect Resistance
Crop
Variety
Resistance to Insects
Brassica (Rapeseed Mustard)
Pusa Gaurav
Aphids
Flat Bean
Pusa Sem2, Pusa Sem 3
Plra (Bhindi)
Pusa Sawani, Pusa A-4
Jassids, Aphids and Fruit
borer
Shoot and fruit borer
Plants Breeding for Improved Food Quality
Nearly 50% of the world population suffers from hidden hunger or deficiency disease because their food is
deficient in one or the other component i.e., micronutrients, proteins, vitamins.
It is, therefore, important to enhance nutritional quality of the crops. Nutritional quality of a crop is the
suitability of the crop in providing proper nutrition to human and animals by having good carbohydrate
content (for calories), protein content with presence of essential amino acids, fats with essential fatty
acids, vitamins, minerals, roughage and absence of antinutritional factors. The breeding programme that
increases levels of mineral, vitamins, complete proteins and healthier fats is called biofortification. Hence
breeding for enhanced nutritional quality is aimed at improving (i) Protein content and protein quality (for
essential amino acids) (ii) Oil content and oil quality (for essential fatty acids), (iii) Higher vitamin content.
(iv) Higher micronutrient and other minerals)
Cereals lack amino acids lysine and tryptophan. In 2000, Maize hybrids were developed which have twice
the amount of lysine and tryptophan as compared to then existing varieties. The trait of high protein content
of old Wheat variety Atlas 66 has been transferred to currently cultivated Wheat varieties. Another development
is Rice variety having five times more iron than the commonly consumed varieties. IARI (Indian Agriculture
Research Institute) has also released a number of biofortified vegetables e.g., vitamin A enriched Carrot,
Spinach and Pumpkin, vitamin C enriched Bitter Gourd, Chenopodium (Bathua), Mustard and Tomato, Iron
and Calcium enriched Spinach and Chenopodium (Bathua) as well as protein rich Broad Bean, Lablab,
French Bean and Garden Pea.
Another requirement of breeding for nutritional quality is to remove antinutritional factors. Antinutritional
factors are toxic factors which are present naturally in plants for protecting themselves against excessive
grazing. They are of several types (a) Glucoinoslates. They are sulphur containing cyanogen-like toxins
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
(e.g., sinigrin in Brassica oleracea, sinalbin and glucobrassicin in Mustard and Rape seed), especially rich
in oils and oil cakes. (b) Cyanogenic Glycosides. Amygedalin in Almond cyanogen in Manihot and Sorghum.
(c) Steroidal Alkaloids. Solanum rubersoum (Potato) (d) Neurotoxic Cyanoalanine. Seeds of Khesari (Lathyrus
sativus) (e) Lectins. They are toxic proteins causing agglutination is of RBCs. Lectins occur in Kidney
Bean and French Bean. Domestication of Potato has removed steroidal alkaloids from tubers but they are
still present in other parts. Boiling and cooking destroy lectins in beans but eating raw soaked beans is
harmful. Rapeseed and mustard are good oil crops but presence of glucoinosolates and fatty acid erucic
acid are harmful. Erucic acid is known to cause damage to cardiac muscle. New varieties like Canola and
Hoya are less toxic. Manihot is repeatedly washed to remove toxin. Excessive use of khesari causes
paraplegia and muscular weakness.
Single cell Protein (SCP)
Single cell protein is protein rich cell biomass which is used as food or feed. Earlier spirulina, a
cyanobacterium (blood-green algae) has long been used as human food and fodder. Microgranisms are
commonly used in raising fermented foods, e.g., curd, cheese, butter, idli, bread, A number of other edible
fungi (e.g., mushroom) and blue green algae (e.g., Nostoc) are also known.
Single cell protein or SCP actually means a protein rich biomass of unicellular microorganisms. However,
it includes biomass of multicellular microganisms as well. (i) SCP can be used as protein rich supplement
of human diet (ii) This will bridge the gap between requirement and supply of protein for human diet and take
off the pressure on agriculture system for increasing the protein content of food articles. (iii) Use of organic
wastes and industrial effluents in raising SCP will help in reducing environmental pollution.
Plant Tissue Culture
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Plant tissue culture is the technique of maintaining and growing plant cells, tissues or organs
aseptically on artificial medium in a suitable container under controlled environmental conditions.
The plant part which is cultured is called explant.
The explants may be root, stem, shoot tip, leaf petioled, embryo etc.
The explants is placed on nutrient medium which contains inorganic salts, certain vitamins, sucrose
and the desired growth regulators.
The growth regulators commonly used implant tissue culture are auxins. like 2, 4-D (2, 4dichlorophenoxyacetic acid) and cytokinins, such as BAP (benzylaminopurine). They are required for
cell division and organ regeneration from the cultures. The cultures are usually kept in a culture room
at about 24oC with some illuminating
Cells and Suspension Cultures
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In callus culture, the explant undergoes cell division and forms and unorganized and undifferentiated
mass of cells called callus. Darkness favour callus formation Differentiation occurs when callus is
exposed to light or provided with growth regulators.
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In suspension culture single cells or small groups of cells are suspended in constantly agitated (at
100-250 revolutions per minute) liquid medium having the auxin 2,4-D. Agitation helps in aeration of
culture, mixing of medium and breaking cell aggregates into smaller cell groups. The cell cultures are
regularly transferred into new culture media to provide better nutrition to the dividing cells. This process
is called subculturing. The callus and suspension culture are used for increasing cell biomass production
and biochemical isolating, regeneration of young plant through tissue culture, production of transgenic
plants and isolation of protoplasts.
Formation of Plantlets

Plant cells cultured in vitro can gives rise to embryoids which can develop into whole plant called
plantlet. This property of developing every somatic cell into a full fledged plant is called totipotency.
This technique was proposed by Haberlandt in 1902 and experimentally confirmed by Steward in 1965
on carrot culture.
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
Meristem Culture
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In case of vegetatively propagated plants, pathogen free clones can be obtained through shoot tip
culture because shoot apical meristem is usually free of the pathogens. The apical meristem is sterilised
and placed over culture medium under aseptic condition. In some cases thiamine or NAA is required
for root initiation. When the plantlet has grown a few leaves, It is subjected to hardening and finally
established in the filed. These explants are also cultured in a medium containing a cytokinin (BAP) as
it promotes axillary branching. Therefore multiple shoots are formed. The technique is, therefore, called
multiple shoot culture. Multiple shoots develop more easily over nodal segments. Meristem cultures
can be used for rapid clonal multiplication, production of virus-free plants, germplasm conservation and
production of transgenci plants.
Embryo Culture


It si the process of taking out young and dormant embryos from developing seeds and their culture on
a nutrient medium to form seedlings and then young plants. Embryo culture has following applications:
During interspecific hybridisation, often the embryo dies quite early, so that no mature seeds can be
obtained. This problem can be overcome, if young hybrid embryos are excised and cultured on a
synthetic medium in vitro to obtain hybrid seedling. This process called embryo rescue has produced
several viable hybrid seedling, e.g., Jut, Tomato, Bean and Rice.
Anther Culture and Haploid Production


(a)
(b)
(c)
(d)
Haploid culture is also known as pollen grain culture or androgenic haploid culture. Guha and
Meheshwari (1964) reported culture of androgenic (of male origin) haploids of Datura inoxia.
Unopened floral buds are first sterilised in 1:3 clorax for 10-20 minutes. The anthers are removed and
kept in culture medium having sucrose, vitamins, auxins and minerals. After 4-6 weeks, the anthers
produce a large number of haploid embryoids. This is also called anther culture. The main importance
of haploid cultures are as follows:
In haploids all mutations show their effect. Therefore, they are useful induction of mutations and also
for mutation breeding.
Colchicine treatment produces pure and perfect homozygous plants in one step which otherwise takes
several years for other normal plants.
Use of haploids in producing pure line has reduced the period required for developing new varieties from
10-12 years to 2-3 years.
The new varieties of plants are superior to other varieties in yield, quality and resistance.
Jhingua1 variety of wheat and guan-18 variety of rice is the result of androfeuic haploid culture.
Protoplast Culture and Somatic Hybridisation
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A hybrid produced by fusion of somatic cells of two species is called somatic hybrid. The process of
producing somatic hybrids is known as somatic hybridisation.
Somatic hybrids in plants were first obtained between two species of tobacco (Nicotianna glauca and
N. Longsdroft) by Carlson et. al. in 1972.
Enzymes like pectinase and cellulase were used to isolate protoplast from cells by digesting cell
walls. The plant cells without cell walls are called protoplasts.
The isolated protoplasts when placed in solutions of suitable osmotic concentration become spherical.
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Fusion between protoplasts of the selected parents is induced by a solution of polyethylene glycol
(PEG), or by a very brief high voltage electric current. The fusion product of two different protoplasts is
called heterokaryon.
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The protoplasts are cultured on a suitable medium where they regenerate cell walls and begin to divide
to produce plantlets. These hybrid plantlets when grown in soil formed full plants. Somatic hybridisation
occurs between sexually incompatible species, permitting.
Pomato is a somatic hybrid between tomato and potato that belong to two different genera. Somatic
hybrids may be used for gene transfer and production of useful allopolyploids and transgenic plants.
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STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
Application of Plant Tissue Culture
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Rapid Clonal Propagation. A Clone is a group of identical cells derived from a single parent individual
or cell through asexual reproduction. A single explant can give rise to numerous plantlets through
callus or suspension cultures which have the same genotype and constitute a clone. These plantlets
can be used for rapid clonal propagation of superior lines, e.g., Palms.
Somaclonal Variation Genetic variations produced in plants regenerated from tissue cultures involving
callus formation are described as somaclonal variations. Some of the somaclonal variations are stable
and useful, e.g. resistance to diseases and pests, stress tolerance, male sterility, early maturation,
better yields, etc. The usefulness of this variability in crop improvement programmes, was first
demonstrated through the recovery of disease resistant plants in:
(a) Potato to Phytophythora infestant which causes late blight diseases,
(b) Wheat tolerant to rust and high temperature
(c) Rice to leaf ripper and Tungro virus
(d) High protein content of potato
(e) Short duration sugarcane and resistance against eye-spot disease and downy mildew, and
(f) Increase shelf-life of tomato.
Transgenic Plants. The plant in which foreign gene is introduced by genetic engineering is called
transgene. Such plants that contain and express a transgene. Such plants that contain and express a
transgene are known as Transgenic organisms. The cells containing transgenes can be grown to
plantlets in vitro. These plantlets give rise to the highly valuable transgenic plants
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