1. Animal Husbandry
n Animal husbandry is the agricultural practice of breeding and raising livestock useful to man.
n Animal husbandry deals with:
(i) breeding of livestock like buffaloes, cows, cattle, sheep, camels, etc., that are useful to humans.
(ii) rearing, catching, selling, etc., of fish, molluscs and crustaceans.
(iii) breeding of fowls for human use.
n India and China cover more than 70 per cent of the world’s livestock population but contribute only 25 per cent to the world farm produce.
2. Dairy Farm Management
n It is the management of animals for milk and its products for human consumption.
n It deals with processes and systems to improve quality and quantity of milk.
n Milk yield primarily depends on the quality of breeds.
n The processes carried out for managing dairy farm are:
(i) Selection of good breeds having high yielding potential and resistance to diseases.
(ii) Cattle is well-housed with adequate water supply.
(iii) Cattle is fed in a scientific manner with good quality and quantity of fodder.
(iv) Hygiene is maintained while milking, storage and transport of milk and its products.
(v) Regular inspections along with keeping proper records.
(vi) Regular visits by a veterinary doctor.
(vii) Hygiene and cleanliness (both of cattle and handlers).
(viii) Identifying and rectifying problems as early as possible.
3. Poultry Farm Management
n The domesticated fowls (birds) used for food or for their eggs are called poultry.
n It includes chicken, duck, turkey and geese.
n The important parameters of poultry farm management are:
(i) selection of disease-free, suitable breeds.
(ii) proper and safe conditions of farm.
(iii) proper food and water.
(iv) hygiene and healthcare of the birds.
4. Bee-keeping (Apiculture)
n The maintenance of hives of honeybees for the production of honey is termed as bee-keeping or apiculture.
n Bee-keeping is practiced in any area where there is availability of sufficient bee pastures of some wild shrubs, fruit orchards and cultivated crops.
n Among several species of honeybees, one of the most common that can be reared is Apis indica.
n A successful bee-keeping requires:
(i) Knowledge of the nature and habits of bees.
(ii) Selection of a suitable location for keeping the beehives.
(iii) Catching and hiving of swarms (groups of bees).
(iv) Management of beehives during different seasons.
(v) Handling and collection of honey and beeswax.
Ecological Importance of Bees
n Bees are the pollinators of many crop species like sunflower, Brassica, apple and pear. So, keeping beehives in crop fields during flowering period increases both crop yield and honey yield.
Commercial Importance of Bees
(i) Honey is used as food of very high nutritive value.
(ii) Honey is also used in the indigenous system of medicines.
(iii) Beeswax produced by honeybees is used in industry to prepare cosmetics and polishes.
5. Fisheries
n It is an industry that includes catching, processing or selling of fish, shellfish (Mollusca, crustaceans, prawn, crabs) or other aquatic animals.
n Some common freshwater fishes are Catla, Rohu and common carp.
n Some edible marine fishes are Hilsa, sardines, mackerel and pomfrets.
Economic Importance
(i) A large part of human population depends on fish and fish products for food.
(ii) It provides income and employment to a large number of fishermen in coastal states.
(iii) Fish liver oil is used in medicines.
S. No. | Aquaculture | Pisciculture |
(i) | It is also known as aquafarming and involves farming of all types of aquatic organisms in coastal and inland areas. | It is also known as fish farming and involves raising fish commercially in tanks for food. |
(ii) | It involves production of all types of aquatic plants and animals – both fresh water and marine. | It involves culture of fish for food and related food animals in water bodies. |
(iii) | There is little requirement of special feed from outside. | Fish feed has to be provided from outside. |
(iv) | Number of economically important substances are obtained. | Yields only food items. |
6. Animal Breeding
n A breed refers to a group of animals related by descent and are similar in most characters like general appearance, features, size and configuration.
n It can also be carried out artificially by artificial insemination and MOET.
n High yielding breed developed at NDRI (National Dairy Research Institute), Karnal is Karan Swiss.
7. Inbreeding
n Inbreeding refers to the mating between closely related individuals within the same breed for 4–6 generations.
Strategy for Inbreeding
(i) Identify superior males and superior females of the same breed.
(ii) These are then mated in pairs.
(iii) Evaluate the progeny obtained from the mating to identify superior males and females.
(iv) In cattle, superior female is the cow or buffalo that produces more milk per lactation and superior male is the bull that gives rise to superior progenies.
(v) Superior progenies obtained are further mated.
Effects of Inbreeding
l Advantages
(i) Inbreeding increases and evolves a pure line.
(ii) Superior genes can be accumulated by inbreeding by eliminating undesirable genes.
(iii) By selection at every step, productivity of inbred population is increased.
l Disadvantages
(i) Close inbreeding usually results in reduction of fertility and productivity. This is called inbreeding depression. Fertility and yield can be restored by mating the selected animals with unrelated superior animal of same breed.
(ii) Recessive genes are exposed by inbreeding which are then eliminated by selection.
8. Outbreeding
n It refers to the breeding of unrelated animals which may be of the same breed but not having common ancestors (out-crossing) or of different breeds (cross-breeding) or even different species (interspecific hybridisation).
(i) Out-crossing
l It is a practice of mating animals of the same breed, that have no common ancestors on either side of their pedigree up to 4–6 generations.
l The offspring is known as an out-cross.
l Advantages
(a) It is done to increase milk production and growth rate in animals.
(b) A single out-cross overcomes inbreeding depression.
(ii) Cross-breeding
l Cross-breeding refers to the mating of superior males of one breed with superior females of another breed.
l A new sheep breed, Hisardale, was obtained in Punjab by crossing Bikaneri ewes and Marino rams.
l Advantages
(a) It helps to accumulate the desirable genes of the two breeds into a progeny.
(b) The progeny may be used for commercial production.
(iii) Interspecific hybridisation
l It refers to crossing between male and female animals of two different species.
l The progeny may or may not be of economic value.
l For example,
(a) a mule was obtained by crossing a male donkey and a female horse.
(b) Hinny was produced by crossing male horse and female donkey.
(c) Liger and Tigon are interspecific hybrid mammals of tiger and lion.
9. Artificial Insemination (AI)
n It is a method of controlled breeding in which semen from the selected male parent is injected into the reproductive tract of the selected female parent.
Advantages
(i) Helps in overcoming several problems of normal mating.
(ii) Semen collected can be frozen for later use.
(iii) Semen collected can be transported in frozen form.
(iv) Useful when desirable bull may not be available at time of heat period of female.
(v) Males have limited ability for mating 50–100 per year in case of bull.
(vi) It is healthier and cannot spread contagious diseases.
(vii) Males of exotic breeds require particular environment/climate.
10. Multiple Ovulation Embryo Transfer Technology (MOET)
n It is a programme for herd improvement in animals like cattle, sheep, rabbits, buffaloes, mares, etc.
n High milk-yielding breeds of female have been bred with high quality (lean meat with less lipid) meat-yielding bulls to increase herd size in lesser time.
Procedure
(i) A cow is administered hormones with FSH-like activity to induce follicular maturation and super-ovulation.
(ii) The cow produces 6−8 eggs instead of one egg produced normally.
(iii) It is now, either mated with an elite bull or artificial insemination is carried out.
(iv) When the fertilised eggs attain 8−32 cells stage, they are non-surgically removed and transferred to a surrogate mother.
(v) The genetic mother can now be again super-ovulated.
11. Plant Breeding
n Plant breeding is the purposeful manipulation of plant species in order to create plant types that are better suited for cultivation, give better yields and are disease resistant.
n The list of traits or characters that the breeders have tried to incorporate into desired crop plants are as follows:
(i) increased tolerance to environmental stress (salinity, extreme temperature, drought).
(ii) resistance to pathogens (viruses, fungi and bacteria).
(iii) increased tolerance to insect pests.
(iv) high-yielding and improved quality of crop plant.
12. Plant Breeding Programme
n Earlier methods of plant breeding involved crossing or hybridising pure lines, followed by artificial insemination to produce plants of desirable traits.
n The major steps in breeding a new genetic variety of a crop are as follows:
(i) Collection of variability
l Genetic variability is the root of any breeding programme.
l Pre-existing genetic variability is collected from wild varieties, species and relatives of the cultivated crop species.
l These are evaluated for their characteristics and preserved for effective exploitation of the natural genes.
l The entire collection of diverse alleles for all genes in a given crop is called germplasm collection.
(ii) Evaluation and selection of parents
l Evaluation of germplasm is carried out to identify plants with desirable combination of characters.
l The selected plants are multiplied and hybridised.
l By self-pollination, pure line is created whenever desired.
(iii) Cross-hybridisation among the selected parents
l The cross-hybridisation between the parents is done to produce hybrids that genetically combine to give desired characters in one plant.
l Cross-hybridisation is a time-consuming and tedious process because it involves emasculation and bagging techniques to transfer desired pollen grains to the desired plant.
l The chances of the desirable characters combining in the hybrid is also one in few thousand crosses.
(iv) Selection and testing of superior recombinants
l It involves the selection of plants among the progeny of the hybrids with desired combination of characters.
l The hybrid are superior to both the parents. This is called hybrid vigour/heterosis.
l They are self-pollinated for several generations till they reach a state of uniformity or homozygosity in order to avoid the segregation of characters in the future progeny.
(v) Testing, release and commercialisation of new cultivars
(a) Evaluation
l The newly selected lines are evaluated for their yield and other agronomic traits of quality, disease resistance, etc., by growing them in the research fields.
l Their performance is recorded under ideal fertiliser application, irrigation and other crop management practices.
(b) Testing
l After evaluation, the hybrid line is tested in farmer’s fields.
l The crop is grown at different locations in the country with different agroclimatic zones for at least three growing seasons.
l The tested material is evaluated in comparison to the best available local crop cultivar (called check or reference cultivar) as a reference material for marketing of the material.
(c) Release
l The material tested is then selected to be certified and released in bulk as a variety.
13. Green Revolution
n The development of several high yielding varieties of wheat and rice in the mid-1960s, as a result of various plant breeding techniques led to dramatic increase in food production in our country. This phase is often referred to as the Green Revolution.
n India is mainly an agricultural country. Agriculture accounts for approximately 33 per cent of Indian GDP and employs 62 per cent of the population.
(i) Wheat and rice
l Between 1960 and 2000, the production of wheat increased from 11 million tonnes to 75 million tonnes while the production of rice increased from 35 million tonnes to 89.5 million tonnes.
l The increase in production was due to introduction of semi-dwarf varieties of wheat and rice.
l Semi-dwarf wheat was developed by Norman E. Borlaug, at International Centre for Wheat and Maize Improvement in Mexico.
l Semi-dwarf varieties of rice were developed from IR-8 (developed at International Rice Research Institute or IRRI, Philippines) and Taichung Native-1 (developed in Taiwan).
l High-yielding and disease-resistant wheat varieties were introduced in India in 1963, e.g., Sonalika and Kalyan sona.
l Semi-dwarf rice varieties were introduced in India in 1966.
l India later developed better rice varieties like Jaya and Ratna.
l Indian hybrid variety of garden pea is P-1542.
(ii) Sugarcane
l Saccharum barberi and Saccharum officinarum were crossed to obtain sugarcane varieties having desirable qualities.
l S. barberi was grown in north India and had poor sugar content and yield.
l S. officinarum did not grow in north India but had thicker stem and higher sugar content.
l The new sugarcane varieties formed by crossing the two varieties had the following qualities:
(a) high yield,
(b) thick stem,
(c) high sugar content,
(d) ability to grow in north India.
(iii) Millets
l Hybrid breeding has led to the development of several high-yielding varieties resistant to water stress.
l Several high-yielding varieties of hybrid maize, jowar and bajra have been successfully developed in India.
14. Plant Breeding for Disease Resistance
n Resistance is defined as the genetic ability of a plant to prevent pathogen from causing disease.
l Advantages:
(i)Development of resistance in crops enhances production.
(ii)Reduces the dependence on fungicides and bacteriocides.
n Diseases can be caused by fungi, bacteria or viruses.
S. No. | Causative organism | Diseases caused |
(i) | Fungi | Brown rust of wheat, red rot of sugarcane, late blight of potato. |
(ii) | Bacteria | Black rot of crucifers, blight of rice, citrus canker. |
(iii) | Virus | Tobacco mosaic, turnip mosaic. |
Methods of Breeding for Disease Resistance
n There are two methods for carrying out breeding:
(i) Conventional breeding techniques
(ii) Mutation breeding
(i) Conventional breeding method
l It is carried out by the following steps:
(a) Selection and screening of germplasm for disease resistance.
(b) Hybridisation of selected plants.
(c) Selection and evaluation of hybrids.
(d) Testing and release of new varieties into the market.
l Following are some of the varieties developed by above mentioned method:
Crop | Variety | Resistance to diseases |
Wheat | Himgiri | Leaf and stripe rust, hill bunt |
Brassica | Pusa Swarnim (Karan rai) | White rust |
Cauliflower | Pusa Shubhra, Pusa Snowball K-1 | Black rot, curl blight black rot |
Cowpea | Pusa Komal | Bacterial blight |
Chilli | Pusa Sadabahar | Chilly mosaic virus, tobacco mosaic virus, leaf curl |
Disadvantages
(a) Limited number of disease resistance genes are present.
(b) Limited number of disease resistance genes have been identified in crop varieties or wild relatives.
(ii) Mutation breeding
l Mutation is a phenomenon by which genetic variation is achieved through changes in the base sequences within genes which creates a new character or trait absent in parental generation.
l Mutation breeding is defined as the process of breeding by artificially inducing mutations using chemicals (like aniline) or radiations (like gamma radiations).
l It is carried out by the following steps:
(a) Inducing mutations in plants by various means.
(b) Screening the plant for resistance.
(c) Selecting the desirable plant for multiplication and breeding.
l In moong bean, resistance to yellow mosaic virus and powdery mildew were introduced by mutations.
l In bhindi (Abelmoschus esculentus), resistance to yellow mosaic virus was introduced from a wild species resulting a new variety called Parbhani Kranti.
15. Plant Breeding for Developing Resistance to Insect Pests
n The host crop plants may be resistant to insect pests due to the morphological, biochemical or physiological characteristics.
n Some characteristics that lead to pest resistance are:
(i) Hairy leaves in plants., e.g., resistance to jassids in cotton and cereal leaf beetle in wheat.
(ii) Solid stem in wheat exhibits non-preference by stem sawfly.
(iii) In cotton, smooth leaf and absence of nectar repel bollworms.
(iv) In maize, high aspartic acid, low nitrogen and sugar content protects them from stem borers.
n The steps of breeding method is same as for the other agronomic traits.
n Some varieties developed by hybridisation and selection are as follows:
Crop | Variety | Insect pests |
Brassica (rapeseed mustard) | Pusa Gaurav | Aphids |
Flat bean | Pusa Sem 2, Pusa Sem 3 | Jassids, aphids and fruit borer |
Okra (Bhindi) | Pusa Sawani Pusa A-4 | Shoot and fruit borer |
16. Plant Breeding for Improved Food Quality
n Need for breeding plants to improve food quality:
(i) Lack of adequate food having adequate nutritional requirements in the world.
(ii) Majority of people are unable to buy enough fruits, vegetables, legumes, fish and meat, and thus suffer from deficiencies or ‘hidden hunger’.
(iii) Essential micro-nutrients are absent from diet.
n Biofortification is the method for developing crops with higher levels of vitamins, minerals, proteins and healthier fats to improve public health.
n The objectives of biofortification is to improve
(i) protein content and quality.
(ii) oil content and quality.
(iii) vitamin content.
(iv) micronutrients and mineral content.
List of Crops with Improved Nutrient Content
l Atlas 66 has been used as a donor for developing wheat varieties with improved protein content.
l Other varieties developed are:
(i) maize hybrids: twice the amount of amino acids lysine and tryptophan than previous varieties.
(ii) iron-fortified rice: increased iron content.
l List of fortified crop varieties released by Indian Agricultural Research Institute, New Delhi:
Crop | Nutrient rich in |
Carrot, spinach, pumpkin | Vitamin A |
Bitter gourd, bathua, mustard, tomato | Vitamin C |
Spinach, bathua | Iron and calcium |
Broad bean, lablab, french bean, garden pea | Protein |
17. Single Cell Protein (SCP)
n It is protein-rich cell biomass used as food or feed.
n It is an alternative protein source for animal and human nutrition from certain beneficial microorganisms like Spirulina.
n Microbes like Spirulina, Methylophilus methylotrophus can be grown on industrial scale as sources of good protein.
n It has been calculated that a 250 kg cow produces 200 g of protein per day. In the same period, 250 g of microbes like Methylophilus methylotrophus produce 25 tonnes of proteins because of its high rate of biomass production.
n Advantages of single cell proteins:
(i) Easy to grow: Microbes can be grown on materials like waste water from potato processing plants, straw, molasses, animal manure and sewage.
(ii) Nutrient-rich: Provide food rich in protein, minerals, fats, carbohydrates and vitamins.
(iii) Reduces environmental pollution.
(iv) High yield: Due to high rate of biomass production and growth, large amounts are produced in short time.
(v) They bridge the gap between requirement and supply of protein.
(vi) They reduce pressure on agriculture.
(vii) They can be easily genetically modified.
18. Tissue Culture
n Tissue culture is an in vitro technique of regeneration of a whole plant from any part of a plant by growing it on culture medium under aseptic conditions.
n The capacity of a cell explant to grow into a whole plant is called totipotency.
n The part of the plant taken for tissue culture is called explant.
n The method of growing or producing thousands of plants through tissue culture is called micropropagation.
n The nutrient medium for tissue culture should have following components:
(i) Carbon source — sucrose
(ii) Inorganic salts
(iii) Growth regulators — auxins, cytokinins, etc.
(iv) Vitamins
(v) Amino acids
n The plants produced from tissue culture are genetically identical to the original plant from which they are grown, so they are called somaclones.
n Advantages of tissue culture:
(i) A large number of plants can be grown in short time.
(ii) Disease-free plants can be developed from diseased plants.
(iii) Seedless plants can be multiplied.
(iv) The plants where sexual reproduction is absent may undergo somatic hybridisation.
(v) Healthy plants can be developed from diseased plants by meristem culture.
19. Somatic Hybridisation
n The process of fusion of protoplast of somatic cells obtained from different varieties or species of plant on a suitable nutrient medium in vitro to develop a somatic hybrid is called somatic hybridisation.
n It is carried out by the following steps:
(i) Single cells from selected plants are isolated.
(ii) The cell walls of cells are digested by enzymes like pectinase and cellulase, to expose the naked protoplasts.
(iii) Naked protoplasts surrounded only by plasma membranes are isolated.
(iv) The isolated protoplasts are fused with the help of PEG (polyethylene glycol) or sodium nitrate to obtain hybrid protoplasts under sterile conditions in special nutrient media.
(v) The hybrid protoplasts are cultured in a suitable media to form new plant.
n Pomato is an example of a somatic hybrid produced by fusion of tomato and potato protoplasts.
n Advantages:
(i) Interspecific and intergeneric hybrids are produced.
(ii) Polyploids and fertile diploids are produced for sexually sterile hybrids.
20. Meristem Culture
n Healthy plants can be recovered from diseased plants by this method.
n Meristem (apical and axillary) is the only virus-free part of a virus-infected plant.
n By removing the meristem and growing it in vitro, virus-free plants can be obtained.
n Some plants developed by meristem culture are banana, sugarcane, potato, etc.
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