STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
INTRODUCTION
- Science of rearing, improvement and caring of domesticated animals is called animal husbandry.
- Domesticated animals, especially the farm animals, kept for profit are collectively called livestock.
E.g., Cow (Bos indicus), buffaloes (Bos bubalus), sheep, goat, pigs, horses, camel etc.
ANIMAL HUSBANDRY
CATTLE
BREEDS OF CATTLE
- There is a variety of breeds of cattle and buffaloes in our country. All of them differ in general body build, colour, form of horns and geographical distribution.
- The best cattle breeds occur in the drier region of the country. There are 26 breeds of cattle.
- In India, the most important breeds of buffaloes are – Surti, Niliravi, Nagpuri (ellichpuri), Jaffrabadi, Bandawari, Murrah, Mehsana.
- Depending upon the utility, the cattle are classified into the following groups
- Milk breeds (Milk producing animal)
- Draught breeds (Used for working)
- General utility breeds (Used for safety)
Table : Important breeds of Indian Cattle
SUPEROVULATION AND EMBRYO TRANSPLANTATION
- Superovulation is a technique where in a cow is made to ovulate more ova by injection of luteinizing hormone (LH).
- High quality cow (e.g., more milk producing) is chosen and is given hormonal injections to induce superovulation.
- Fertilization is achieved by artificial insemination.
- From this cow, 4 to 10 embryos are collected at a time.
- Each of the embryo is transplanted into carrier cow (Surrogate mother).
- By deep freezing (– 196°C), it is possible to preserve the seven days old foetus for several years and transplanted when required.
- This embryo transplantation technique can also be used for other livestock like sheep and goat etc.
- Fertility in local breeds of cattle has been overcome through the use of pregnant mare serum gonadotropin(LH + FSH).
- Sterile and immature cows can be induced to lactate through stilbestrol.
CATTLE DISEASES
- Anthrax, foot and mouth disease, rinderpest, black quarter, blue tongue, mastitis, tuberculosis are some of the common diseases among farm animals.
- Use of uncontaminated water, fodder and proper nutrition, immunization and sanitation make the animals disease resistant.
- Lice, ticks are external parasites of cattle.
SHEEP (OVIS ARIES)
- Today, sheep are raised in all parts of the world. They are reared for wool and mutton, mostly in hilly tracts.
- Sheep graze on grass and herbs.
- Farm waste, mineral mixture, oil cake and other cattle feeds can also be given.
- The fine soft wool (called Pashmina) is the underfur of Kashmir and Tibbet goat.
- High quality soft wool shahtoosh is obtained from the animal Chiru.
- A sheep lives for about 13 years.
Table : Some breeds of Indian Sheep
BREEDING OF SHEEP
- Sheep begin breeding at the age of about two years and then have young ones every year.
- After that, sheep feed on tender grass, weeds of pasture and hill side.
- To improve the quality of a sheep, cross breeding experiments are usually done.
For this purpose, a good quality wool yielding or mutton producing sheep is chosen and cross breed with-exotic breed like Dorset, Horn and Merino.
GOAT (CAPRA)
- Goat is also called poor mans cow because it yields a small quantity of milk and feeds on a variety of wild plants even prickly ones.
- Goat destroy vegetation and forests if not kept under control.
- bout 19% of world goat population occurs in India.
- Goats are reared in open sheds.
- The wild goat Baluchistan and Sindh is the ancestral stock of all breeds of domesticated goats.
- An adult male goat is also called bully goat or a buck and a female adult is a nanny goat or a doe.
- The goats are less prone to serious diseases. They suffer from some contagious diseases such as anthrax, goat pox, pleuropneumonia and foot and mouth disease. The general signs of illness are as in the cows. Parasitic infection is common in goats.
Table : Indian breeds of goats
HORSES
- The horses (Equus cabalus) are solid- hoofed, non-ruminant quadrupeds with long, pendant mane and tail bearing long hair all over.
- If compared to other animals, horses have a low reproductive rate. Controlled natural mating in horses has been in practice in India for a long time. A high professional skill is required for rearing, training and medical care of race horses.
Table : Breeds of Indian Horses
POULTRY
- Poultry is rearing of domesticated fowls (chicken), ducks, geese, turkeys, guinea fowls, pigeons, partridges, etc. for the meat and eggs.
- Poultry and poultry products are a rich source of animal protein and the right kind of fats for good health.
- In our country, poultry mainly means domestication of chickens for meat and eggs.
- Poultry birds are easy to raise and can acclimatize to a wide range of climate conditions. They are prolific (highly reproductive and have a short life span).
- Poultry farming yields quick return, needs little space and easy to manage.
- Chickens are bred in large colonies in special places called poultry farms.
- The poultry birds are kept in dry comfortable and well ventilated cages.
- Domestic fowl (Gallus domesticus) constitute the major poultry bird.
- Poultry birds exclusively grown for meat are called broilers (e.g., Plymouth rock), layers are for egg production, cockerel are young male fowls and rooster are mature male fowls.
- Broilers are generally quick growing birds which are generally males but can also be female. Broilers are sold in fresh and frozen form after dressing (removal of feathers, head and feet).
- The domestic fowl (gallus gallus) can be classified as –
- Indigenous (Desi) or Indian breeds
- Aseel, Ghagus, Karaknath, Brahma, Bursa, Black Bengal, Chittagong, Tellicherry, etc.
- Assel is best game bird, it is used in cock fighting.
- Indian breeds are slow growing, less efficient converters and produce fewer eggs (60/years).
- Exotic Breeds
- White leghorn, Red Rhode island, Plymoth rock, New Hampshire, Sussex, Barre Plymoth, Austraiorp, Light, Minoreha etc.
- HH 260 lays more than 260 eggs in a year and its mortality rate is low.
- The broilers (bird grown for meat), with high nutritive value have been produced by cross breeding (heterosis).
COMMON DISEASE OF POULTRY
- Viral diseases : Fowlpox, infectious bronchitis, lymphoid leukosis and ranikhet diseases are common viral diseases of poultry. Ranikhet (New Castle) disease is the most common disease of hens and fowls in which the affected individuals suffer from fever and diarrhoea. With the progression of this disease, the birds show mucus secretion from their beaks, paralysis of wings and birds repeatedly moving round.
- Bacterial diseases : These include fowl cholera, Pullorum, Coryza, Mycoplasmosis and Spirochaetosis.
- Fungal diseases : These include Aflotoxicosis, Brooder pneumonia and aspergillosis.
- Parasitic diseases :
- Internal parasites : Roundworms, tapeworms and threadworms.
- External parasites : Fowl mite, chicken mites, fleas, ticks etc.
If any of the infectious disease has affected a mass proportion of the chicken and hens, then the best and safer decision to avoid the fatal consequence is to destroy the affected individuals.
POULTRY DEVELOPMENT IN INDIA
Poultry contributes about Rs. 7,500 crores to the Gross National Product (GNP) of India. India ranks fifth in the world's egg production. Egg is one such food commodity which cannot be adulterated. The average per capita consumption is about 32 eggs and 600 grams of poultry meat a year. At present, poultry is estimated to provide employment to about seven lakh families.
ANIMAL BREEDING
- Animal breeding aims at improving the genotypes of animals to make them more useful to us.
- The chief objectives of animal breeding may be summarised as follows :
- Improved growth rate.
- Increased production of milk, meat, egg, wool, etc.
- Superior quality of resistance to various diseases.
- Increased productive life.
- Increased or at least, acceptable reproduction rate etc.
- A variety of strategies have been used for breeding of animals. The main approaches for animal breeding, viz., inbreeding, out-breeding, out-crossing, cross breeding and interspecific hybridization, are briefly described below which are based mainly on the breeding work with cattle.
IN-BREEDING
- In-breeding refers to the mating of more closely related individuals within the same breed for 4-6 generation.
- All domesticated animals have male and female individuals. As a result, these are strictly cross-fertilized and highly heterozygous. Each domesticated animal species consists of several distinct breeds that differ from each other in several morphological and other features. Animals belonging to a single breed differ from each other in genotype because of the mode of their reproduction and their heterozygous nature. Therefore, mating between animals of the same breed provides opportunities for genetic improvement. Superior cows and superior bulls of the same breed are identified and mated in pairs. The progeny obtained from such mating are evaluated and superior males and females are identified for further mating. A superior female, in the case of cattle, is a cow that produces more milk or lactation. On the other hand, a superior male is that bull, which gives rise to superior progeny as compared to those of other males. Inbreeding, as a rule, increases homozygosity.
- In-breeding exposes harmful recessive genes that are eliminated by selection.
- In-breeding also helps in accumulation of superior genes and elimination of less desirable genes. Therefore, this approach increases the productivity of inbred population. Practically, every breed was developed by some type of inbreeding.
But continued inbreeding, especially close in-breeding, usually reduces fertility and even productivity (inbreeding depression). Whenever this becomes a problem, the selected animals of the breeding population should be mated with such superior animals of the same breed that are unrelated to those in the breeding population.
- In-breeding depression refers to the loss of vigour associated with inbreeding.
OUT-BREEDING
- Outbreeding is the breeding of unrelated animals, which may be between individuals of the same breed (but having no common ancestors), or between different breeds (cross breeding) or different species (interspecific hybridization).
OUT-CROSSING
- Out-crossing is the practice of mating of animals within the same breed but having no common ancestors on either side of their pedigree up to 4-6 generation.
- The offspring of such a mating is known as an outcross.
- A single outcross often helps to overcome in-breeding depression.
CROSS-BREEDING
- In cross-breeding, superior males of one breed are mated with superior females of another breed.
- Cross-breeding allows the desirable qualities of two different breeds to be combined in a single breed. The progeny animals may themselves be used as hybrids for commercial production. Alternatively, they may be subjected to some form of inbreeding and selection to develop new stable breeds that may be superior to the existing breeds. Many new animal breeds have been developed by this approach.
- Progeny produced through cross-breeding may be mated according to various schemes to achieve specific objectives. For example, cows of an inferior breed may be mated to bulls of a superior breed. In each successive generation, the progeny cows are mated to the bulls of the same superior breed that was used in the original cross. Thus, in 6-7 generations, the progeny will be almost similar to the breed of bulls used for the mating. But these progeny would retain some original advantageous conditions, etc., of the other breed from which the cows were used in the original mating.
- Hissardale is a new breed of sheep developed in Punjab by crossing Bikaneri Eves and Marino rams.
INTERSPECIFIC HYBRIDIZATION
- In this strategy, male and female animals of two different species are mated. The progeny obtained from such a mating are usually different from both the parental species.
- In some cases, the progeny may combine desirable features of both the parents, and may be of considerable economic value. An example of this type is mule, which is produced from a cross between a female horse (mare) and male donkey. Mules are sturdier and hardier than their parental species, that are well suited for hard work in difficult terrains like mountainous regions.
APICULTURE
- The scientific method of care and management of honey bees is called apiculture. Although bees are very active throughout the year but in winter they become sluggish and very active in spring.
- Honeybee is a social insect and show polymorphism and good division of work.
- The diameter of a normal bee hive is about 30-90 cm. In it, the number of bees is about 50-60 thousands.
- Bee-Hive : Honey bee is one of the few domesticated insects. In modern days, bee colonies are reared in artificial wooden boxes for maximum production of honey and wax. The artificial box where the bee colony is maintained and managed is called hive. The place where hives are kept and managed is called apiary.
- The hives should be set in places where there are plenty of flowering plants. The place should be neat and clean and free from any obnoxious smell. There should be clean drinking water nearby because each bee colony requires two glasses of water per day for their survival.
- Bees are pollinators for sunflower, Brassica, apple and pear.
IMPORTANT VARIETIES OF HONEYBEE
- Apis dorsata (Rock bee) : It is also named as sarang bee. It is of largest size and produces highest yield of honey. However, it is of highly aggressive nature and migratory species which is not suitable for rearing by man.
- Apis indica (Indian Mona-bee) : It lives across the whole country of India and is smaller in size than sarang-bee. It is mild in nature so that it is easily manageable during rearing. Mona-bee yields about 3-4 kg. of honey per hive.
- Apis florea (Bhringa-bee) : This bee is smallest in size and of timid nature. It only yields about 250gms. of honey every hive. Hence, it is not suitable for commercial purpose.
- Apis mellifera (European bee) :This bee is of mild nature. It yields 9-10 times more honey than mona-bee. It is the most useful bee for commercial purpose. The Italian variety of this species is by far the most important variety.
SOCIAL ORGANISATION
- A highly organised division of labour is found in the colony of honey bee.
- Each colony has 40,000 to 50,000 individual consisting of 3 casts - queens, drones and workers.
QUEENS
- It is about 15-20 mm long and its body is about three times larger and 3 times heavier than a worker bee. It lives only for 5 years. The legs and wings are short but crop is long. It has ovary which is filled with eggs.
- Only one queen develops from fertilized egg (i.e. it has 32 chromosomes). It feeds on Royal jelly. Its sole function is reproduction. It lays 2000 eggs everyday. One queen lays approx. 1500000 egg in its whole life time.
DRONES
- Drones are males which mate with the queen. Their number in the colony is not much. They are smaller but shorter than queen with broader abdomen, longer appendages and larger wings.
- Drones are developed from unfertilized eggs so there are only 16 chromosomes present in them.
- In drones, salivary and wax secreting glands and stings are absent.
- Their life span is of 45 days or 5 weeks.
- Like the queen, they also depend on worker bees for nutrition.
- Their sole duty is to fertilize the queen.
WORKERS
- Their number is maximum in a hive.
- They are darker and the smallest bees of the colony.
- Their wings and mouth parts are very strong.
Their mouth parts and legs are modified to suck the nectar of flowers and to collect the pollen grains respectively.
- Pollen basket is present on hind leg (tibial) for collection of pollen. Pocket like wax glands are present at base 2nd to 5th abdominal segment.
- Worker bees are sterile females. These are developed from fertilized eggs. Due to high labour, the lifetime of a worker bee is about 6-8 weeks.
LIFE CYCLE
- When the colony becomes overcrowded, the old queen leaves the hive along with some workers and drones. They fly to a new place to establish another colony. This is called swarming.
- Swarming takes place during the spring or early summer. New queen is then formed in the old colony. She soon undertakes a marriage or nuptial flight with the drones. Mating occurs in the air.
- Drones die during the course of copulation. The queen mates only once in a lifetime.
- After mating, the queen generally lays one egg in one brood cell.
- he eggs are pinkish coloured, elongated with cylindrical body generally attached to the bottom of the cell.
- Larvae emerge out from both the fertilized as well as unfertilized eggs. Thus, the larvae from the unfertilized eggs form the drones while the workers are developed from the larvae of the fertilized eggs. Amongst the larvae of the workers, one is fed on the royal jelly, a special diet secreted by the young workers in the colony, and becomes the queen of the colony.
- The royal jelly consists of digested honey and pollen, mixed with a glandular secretion into the mouth of the workers.
- The life cycle of honeybees includes complete metamorphosis or holometabolic development.
- The worker bees have a pollen collecting apparatus, honey storing mechanism and wax secreting glands.
Fig. : Life cycle of Apis indica
ECONOMIC IMPORTANCE
- Formation of honey : Honey is a viscous sugary fluid formed from the nectar within the stomach of the honey bee. The bees visit flowers, suck the nectar, store it in the stomach and return to the hive. In the stomach, the nectar is processed. It is regurgitated and swallowed repeatedly for about 240 times. Then the processed nectar is deposited in the comb cells. This processed nectar is called unripe honey or green honey. It contains about 80% water. The unripe honey is converted into ripe honey by evaporation. The ripe honey contains less than 20% water. When the honey becomes ripe, the cells are capped or closed. The honey in the unsealed cell is unripe.
- Bee wax : Bee wax is secreted by the abdominal gland of bees. It is used for the construction of comb. It is a yellowish solid, insoluble in water. It is used for the preparation of paints, varnishes, candles, models, etc. It is used as a ground substance for the preparation of ointments, creams etc. It has many industrial uses. It is used extensively in engineering industries, railways, textiles, leather industries etc.
- Bee venom : Bee venom is secreted by the poison-glands of stings. Bee venom is a curative toxin in humans. It is transparent and it has a bitter, burning taste. It is acidic in nature. It contains formic acid, histamine, tryptophan, sulphur, many proteins, volatile oils, enzymes like hyaluronidase and phospholipase and magnesium phosphate.
- Propolis : It is a resin derived from plants (axillary buds). It has antiseptic and antibiotic properties.
FISHERIES
- Fishes and other aquatic animals are reared and caught for food which is rich in protein, vit. A and D.
- Aquaculture is rearing and management of useful aquatic plants and animals like fishes, oyster, prawns, mussel etc.
- Pisciculture is rearing, catching and management of fishes.
- Culture fishery is the raising of fishes in tanks and ponds.
- Capture fishery is management of catching of fish without actually raising them.
- Inland fisheries includes culture and capture fishery.
- The per capita consumption of fish in India is estimated at 1.52 kg/yr.
- India is at present the 6th foremost sea food producing nations in the world.
- Blue revolution is effort to increase fish yield in India.
Table : Cultivable fish species
PLANT BREEDING
- The branch of botany, which is related with the studies about genetic improvement of crop plants is known as plant breeding. Improved varieties of crop plants are developed by its application.
- Improvement of crop plants is made to obtain following characters :
- Increased yield of seeds, oil and fibres.
- To develop, insect, disease and frost resistance.
- To acclimatize in adverse conditions.
- To change maturation period.
NOTES
EMINENT PLANT BREEDER
- Norman Borlaug : He was famous plant breeder of Mexico, who proposed dwarf varieties of wheat, e.g., Sonora-64, and Lerma Rojo-64. These are high yielding varieties. He was awarded Nobel prize for peace on the basis of this substantial contribution in resolving food problem of world. He is also known as Father of Green Revolution.
- Dr. M.S. Swaminathan : Mainly contributed in mutation breeding. He developed "Sharbati sonora" variety of wheat by mutation breeding. He is also known as "Father of Indian Green revolution".
METHODS OF PLANT BREEDING
- Methods of plants breeding are –
- Plant introduction and Acclimatization
- Selection
- Hybridization
- Polyploid breeding
- Mutation breeding
- Tissue culture
PLANT INTRODUCTION AND ACCLIMATIZATION
- This is the easiest and most rapid method of crop improvement. The growing or establishment of a plant to a new place, by transfer from its centre of origin is known as plant introduction.
- If the plant material is brought from foreign country then it is known as exotic collection and if it is brought from some other place of the same country then it is known as "Indigenous collection".
- Acclimatization is the adaptation of introduced plant in newly changed climatic conditions. First of all introduced plant material is put to quarantine law/plant-protection inspection. During this process, inspection or screening is made about the presence of weed or insect pest along with introduced plant. Once the plant material is found totally suitable then only it is used for agriculture.
- Several weeds, e.g., Argemone mexicana, Eicchornia and Parthenium also invaded our country due to uncontrolled introduction.
SELECTION
- This is most primitive and simplest method used for crop improvement.
- Selection is sorting out of the plants having desired characters e.g., high yield or disease resistance from plant population on the basis of homozygous characters. Plant selection is always done by breeder, e.g., in case of maize dispersal and propagation is done by man, hence it is known as "pampered corn."
- There are three methods of artificial selection :
- Pure line selection : Progeny of self pollinated homozygous plant is known as pure line. This word was coined by Johanson (1903). To develop new variety from pure line is known as pure line selection. This method is only useful for self pollinated crops,
e.g., Wheat. - Mass-selection : This method is applied for self as well as cross pollinated crops both, but more useful for cross pollinated crops. It is based on external characters only.It is the easiest and quickest method of crop improvement.
- Clonal selection : This method is used for vegetatively propagated crop plants, e.g., sugarcane, banana and potato etc. The progeny of vegetatively propagated parent is known as clone which are similar to their parent plants. Therefore, selection in between clones is done in this method on the basis of phenotypic characters. There are certain limitations of clonal selection, these are :
- This method can be used for vegetatively propagating crop plants only.
- New variations are not observed.
HYBRIDIZATION
- When new variety of a crop plant is developed by the cross of 2 genetically different plants, then it is known as hybridization.
- The plants which are crossed may be of same or different species or genera.
- The progeny obtained due to cross between two genetically different parents, appeared to be more robust, vigorous and of higher yield in comparison to its parents, this phenomenon is known as hybrid vigour or "heterosis". It is developed due to heterozygosity.
- Heterosis gets disappeared due to inbreeding. Hybrid vigour remains maintained in vegetatively propagated plants.
- Basic steps of hybridization are as follows –
- Selection of parents
- Self pollination in parents which induces homozygosity.
- Emasculation : Removal of anthers or male reproductive structures before maturation of flower.
- Bagging : To avoid contamination by unwanted pollen, the female and male flowers are covered with cellophane or parchment or paper bags. This process is called bagging. Female flower is covered by a bag. Bagging is mainly done to check undesired cross pollination.
- Cross is made between selected parents with desired characters.
POLYPLOID BREEDING
- The plants which have more than 2 sets of chromosomes are known as polyploids.
- There are various types of plants on the basis of chromosome set numbers. E.g., monoploid, diploid, triploid, pentaploid (e.g., wheat) and hexaploid and so on.
- Triploidy is of general occurrence in various crop plants. These triploids are usually seedless or parthenocarpic, e.g., most of the banana species are triploid hence, their fruits are seedless (parthenocarpic).
- In sexually reproducing members, polyploidy is generally evolved due to fusion of egg with more than one male gametes. Besides this, polyploidy can be artificially induced by the treatment of colchicine (an alkaloid obtained from Colchicum-autumnale.) Some triploid plants have got more vigour and large sized fruits. E.g., Apple and pear.
MUTATION BREEDING
- Various important varieties of numerous crop plants have been developed by mutation breeding. E.g., "Sharbati Sonora" and "Pusa lerma" varieties of wheat have been evolved by gamma radiation mutation treatment of dwarf varieties "Sonara" and "Lerma rojo".
- "Sharbati Sonora" is responsible for "Green revolution".
- Similarly, Remei and Atomita-2 varieties of rice have also been developed by mutation breeding. Erectoides and Erectiferum varieties of Barley were also developed by mutation breeding.
- The world fame Aruna variety of castor well known for its disease resistance and high yield of oil is also obtained by mutation breeding only.
- By U.V. Rays treatment of P. chrysogenum and P. notatum, the production of penicillin is enhanced.
- Some important limitations of mutation breeding are :
- Most of the mutations are recessive.
- Rate of mutations is quite meagre.
- Most of the induced mutations are useless for the plant breeders because these are lethal.
- Sometimes stability of mutants is doubtful. Some mutants get back their normal type once again.
TISSUE CULTURE
- Tissue culture is a modern method of crop improvement. It is based on totipotent nature of plant cell or phenomenon.
i.e. every type of totipotency plant cell has got the capability to develop into a new plant. - The principle of totipotency was put forward by Haberlandt, but elaborated by Steward through his experiments. He developed a completely natural wild carrot plant by tissue culture of a single cell from root apex.
- A single cell or a group of cells used in tissue culture method, is known as explant. As a result of explant culture in culture medium, an irregular group of cells is formed which is known as callus.
- Later on necessary concentrations of auxins and cytokinins are added in culture media and root and shoot formation is stimulated. This process is known as organogenesis. In this manner, a complete plantlet is developed by single cell culture. Later on, it is grown in soil or flower pots for further growth.
- Practical applications of tissue culture for crop improvement are :
- Micropropagation, by which numerous plantlets are developed in a limited space which can be later utilized for agriculture or horticulture, or forestry.
- Androgenic haploids : Haploid plants are developed by anther culture technique. These are known as androgenic haploids. Guha and Maheshwari first of all obtained androgenoic haploids by anther culture of Datura innoxia. Androgenic haploids are very much useful in plant breeding because –
- Only one set of chromosomes is found in haploid plants. Therefore, slightest variations can also be easily detected.
- These haploid plants are used for the production of homozygous diploids (by colchicine treatment) and later on these homozygous diploids may be used as parents.
- Production of disease free plants : These can be developed by shoot tip culture. Because "shoot apex" does not get effected by virus.
- Culture of rare hybrids : The hybrid plants obtained by interspecific or intergeneric cross are mostly sterile, because their embryo becomes abortive in earlier or later stages. These rare hybrids can be preserved by embryo culture.
- Somatic or protoplast hybridization: In this method, protoplasts from cells of two genetically different species are made to fuse. With the help of cellulase or pectinase enzymes, cell wall of the cells is separated as a result of which walless cells or protoplasts are formed. Fusion of protoplasts is done. Pomato and Bromato hybrids have been developed by this method.
Potato × Tomato → Pomato
Brinjal × Tomato → Bromato
- Somaclonal variations : The variations amongst the plants developed by tissue culture method are known as somaclonal variations. These variations are stable and useful for agriculture, e.g., pest and disease resistance.
INTERNATIONAL EFFORTS FOR UTILIZATION OF CROP GERMPLASM
- Cereals, e.g., wheat, rice, barley, sorghum, maize and pearl millet are basic food sources for human population. Out of this, rice is the main food source for more than 50% of the population.
- Improvement in rice : For the enhancement in crop yield in rice, a dwarf variety gene "De-Geo-Woo-Gene" was brought from Taiwan.
- IRRI (International Rice Research Institute, Los Banos, Philippines) utilized this gene in developing early ripening varieties IR-8 and IR-24 of rice with higher crop yield.
NOTES
Under supervision and direction of Dr. Gurdev Singh Khush, 13 varieties of rice (brought from 6 countries) were crossed with a wild species Oryza nivara and a new improved variety IR-36 was developed in IRRI Manila. This variety is resistant against grossy, stunt virus. IR-36 variety of rice is well known for higher crop yield, and has been helpful in solving major food problem of Asia.
PLANT BREEDING FOR DISEASE RESISTANCE
- Diseases are the main enemies of the crops and they cause enormous loss to the agricultural production of the country.
- Breeding for disease resistance is carried out by the conventional breeding techniques or by mutation breeding.
- The conventional method of breeding for disease resistance is that of hybridization and selection.
- Disease resistance is the ability of plants to withstand, oppose or overcome the attack of pathogens.
Table : Some crop varieties developed by hybridization and selection, for disease resistance against fungi, bacteria and viral diseases
Table : Some crop varieties developed by hybridization and selection against insect pest resistance :
PLANT BREEDING FOR IMPROVED FOOD QUALITY
- Improved food quality is an important aspect for plant breeders because it determines the suitability of plant product for various uses.
- Breeding for improved food quality is undertaken with objectives of improving-
- Protein content and quality
- Oil content and quality
- Vitamin content
- Micronutrient and mineral content.
- Biofortification is the process of breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats is the most practical means to improve public health.
- Through biofortification , scientists can provide farmers with crop varieties that naturally reduce anaemia, cognitive impairment and other nutritionally related health problems.
SINGLE CELL PROTEIN
- Single cell protein is a microbial biomass. This biomass is obtained from both unicellular and multicellular microorganisms. Single cell protein can be produced using algae, fungi, yeast and bacteria.
- Commercial production of S.C.P. is mostly based on yeasts and some other fungi, e.g., Fusarium graminearum.
- Production of SCP requires carbon source as well as nitrogen, phosphorus and other nutrients needed to support optimal growth of the selected micro-organism. SCP process are highly aerobic (except those using algae). Therefore, aeration must be provided.
ADVANTAGES OF SCP
- The SCP is rich in high quality protein and is rather poor in fats, which is rather desirable.
- They can be produced all year round and are not dependent of the climate (except the algal processes).
- SCP may be used directly as human food supplement, or else it may be used in animal feed to at least partially replace the currently used protein-rich soyabean meal and fish proteins, and even cereals, which can be diverted for human consumption.
- The microbes are very fast growing and produce large quantities of SCP from relatively small area of land. For example, 250 gm of Methylophilus methylotrophus, a microorganism, can produce 25 ton protein.
- These use low cost substrates and in some cases, such substrates which are being wasted and causing pollution to the environment.
- When the substrate used for SCP process is a source of pollution, SCP production helps reduce pollution.
- Strains having high biomass yields and a desirable amino acid composition can be easily selected or produced by genetic engineering.
- Some SCPs are good sources of vitamins, particularly B-group of vitamins e.g., yeasts and mushrooms.
- At present, SCP appears to be the only feasible approach to bridge the gap between requirement and supply of proteins.
Study Notes for NEET/AIIMS/JIPMER
