Sunday, December 27, 2020

Strategies for Enhancement in Food Production | Plus 2 Botany | Exam Capsule Notes

STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION: 
CHAPTER AT A GLANCE

I. ANIMAL HUSBANDRY

Scientific agricultural breeding practice and raising livestock.

1. Dairy Farm Management (Dairying): 
  • For increasing yield and quality of milk and its products. 
  • Ways for the yield potential: Look after the cattle, Feeding of cattle in a scientific manner, Cleanliness and hygiene.
2. Poultry Farm Management: 

Its components are: 
  • (i) Selection of disease free & suitable breeds. 
  • (ii) Proper and safe farm conditions. 
  • (iii) Proper feed and water. 
  • (iv) Hygiene and health care.
Animal Breeding

Modification of genotype of an organism to make it more useful to humans. E.g. Jersey (cattle), Leghorn (chicken).

2 types: Inbreeding and out-breeding.

a) Inbreeding: 

Mating of closely related individuals within the same breed for 4-6 generations. This strategy is as follows:
  • Identify and mate superior males & females of same breed.
  • Evaluate the progeny obtained and identify superior males and females among them for further mating.
Advantages of Inbreeding: (i) Increases homozygosity. (ii) Exposes harmful recessive genes that are eliminated by selection. (iii) Helps in accumulation of superior genes.

Inbreeding depression: Reduction in fertility and productivity due to continued inbreeding. To solve this problem, mate selected animals with unrelated superior animals of the same breed.

b) Out-breeding: 

Breeding of the unrelated animals. 3 types:

1. Out-crossing: Mating within the same breed, but having no common ancestors up to 4-6 generations. The offspring of such a mating is known as out-cross. Best method for animals having low milk productivity, growth rate in beef cattle, etc. It overcomes inbreeding depression.

2. Cross-breeding: Mating of superior males of one breed with superior females of another breed to combine desirable qualities. E.g. Bikaneri ewes X Merino rams = Hisardale (sheep).

3. Interspecific hybridization: Mating of male and female of two different species. E.g. Mule (male ass X female horse).

Controlled breeding experiments

1. Artificial insemination: Injection of semen from male parent into the reproductive tract of selected female.

2. Multiple Ovulation Embryo Transfer Technology (MOET): A cow is administered hormones such as FSH to induce follicular maturation & super ovulation. The animal is either mated with an elite bull or artificially inseminated. Fertilised eggs at 8–32 cells stage are recovered and transferred to surrogate mothers.

Bee-keeping (apiculture)

Maintenance of honeybees to produce honey and beeswax. 

Most common species: Apis indica.

Important points for successful bee-keeping: 
  • Knowledge of the nature and habits of bees.
  • Selection of suitable location for beehives.
  • Catching and hiving of swarms. 
Fisheries

An industry of catching, processing or selling of fish, shellfish or other aquatic animals.

Freshwater fishes: Catla, Rohu, common carp etc. 

Marine fishes: Hilsa, Sardines, Mackerel, Pomfrets etc.

Aquaculture: farming of aquatic organisms. Pisciculture: farming of fishes.

Blue Revolution: The development of the fishery industry.

II. PLANT BREEDING

Manipulation of plant species to create desired plant types for better cultivation, better yields and disease resistance.

Green Revolution: The development and flourishing of the agriculture. It was dependent on plant breeding.

Desirable traits for plant breeding:
  • Increased crop yield and quality.
  • Increased tolerance to environmental stresses, resistance to pathogens and insect pests.
Steps of Plant breeding:
  1. Collection of genetic variability from wild relatives: The entire collection of plants/seeds having all the alleles for all genes in a crop is called germplasm collection.
  2. Evaluation and selection of parents from germplasm.
  3. Cross hybridisation of the selected parents with desired characters to produce hybrid. Limitations: Very time-consuming and tedious process, Hybrids may not combine the desirable characters. 
  4. Selection & testing of superior recombinants: These are self-pollinated for several generations till they reach a state of uniformity (homozygosity), so that the characters will not segregate in the progeny. 
  5. Testing, release & commercialization. 
Norman E. Borlaug developed semi-dwarf wheat.

Sonalika & Kalyan Sona: High yielding & disease resistant wheats.

Semi-dwarf rice varieties were derived from IR-8, (developed at International Rice Research Institute (IRRI), Philippines) and Taichung Native-1.

Jaya & Ratna: Semi dwarf varieties developed in India.

Sugar cane: Saccharum barberi X S. officinarum → hybrid sugar cane.

Plant Breeding for Disease Resistance

Some plant diseases

Fungal: Rusts

Brown rust of wheat, Red rot of sugarcane, Late blight of potato

Bacterial

Black rot of crucifers

Viral

Tobacco mosaic, Turnip mosaic


Methods of breeding for disease resistance:

1. Conventional breeding:

Some crop varieties bred by Conventional method

The steps are:
  • Screening germplasm for resistance sources.
  • Hybridisation of selected parents.
  • Selection & evaluation of the hybrids.
  • Testing and release of new varieties.

Some crop varieties bred by Conventional method

Crop

Variety

Resistance to

Wheat

Himgiri

Leaf & 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.


2. Mutation breeding: The breeding by mutation using chemicals or radiations to produce plants with desirable characters.

E.g. In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations.

Resistant genes from wild species have introduced into high-yielding varieties. E.g. In bhindi (Abelmoschus esculentus), resistance to yellow mosaic virus was transferred from a wild species. It resulted in a new variety called Parbhani kranti.

Plant Breeding for Developing Resistance to Insect Pests

Morphological, biochemical or physiological characteristics give insect resistance in host crop plants. E.g.
  • Hairy leaves: E.g. resistance to jassids in cotton and cereal leaf beetle in wheat.
  • Solid stems in wheat → non-preference by the stem sawfly.
  • Smooth leaved and Nectar-less cotton varieties → do not attract bollworms.
  • High aspartic acid, low nitrogen and sugar content in maize → resistance to maize stem borers.
Some crop varieties bred for insect pest resistance:

Crop

Variety

Insect pests

Brassica (rapeseed mustard)

Pusa Gaurav

Aphids

Flat bean

Pusa Sem 2, Pusa Sem 3

Jassids, aphids & fruit borer

Okra (Bhindi)

Pusa Sawani, Pusa A-4

Shoot and Fruit borer


Plant Breeding for Improved Food Quality

Breeding crops with higher levels of nutrients is called Biofortification. E.g.

Maize hybrids

Twice amount of amino acids, lysine & tryptophan.

Wheat variety, Atlas 66

High protein content

Iron-fortified rice variety

Five times as much iron as in common varieties

Vegetables rich in vitamins & minerals

By Indian Agricultural Research Institute, New Delhi


SINGLE CELL PROTEIN (SCP)

It is the protein derived from single-celled organisms.

It is an alternate source of proteins for animal and human nutrition. E.g. microbes like Spirulina.

Spirulina is rich in protein, minerals, fats, carbohydrate & vitamins. It is grown on materials like waste water from potato processing plants, straw, molasses, animal manure & sewage. This also reduces environmental pollution.

A micro-organism like Methylophilus methylotrophus produce 25 tonnes protein/day.

TISSUE CULTURE

A technique of growing plant cells/tissues/organs in sterile culture medium under aseptic conditions.

Totipotency: The ability to generate a whole plant from any cell/explant.

Explant: Any part of a plant that is grown in a test tube under sterile nutrient media.

Micropropagation: The method of producing thousands of plants in very short time through tissue culture.

These plants will be genetically identical to original plant, i.e., they are somaclones.

Tissue culture is also used for recovering healthy plants from diseased plants. The meristem (it will be free of virus) from infected plant is removed and grown it in vitro to obtain virus-free plants.

Somatic hybridization: It is the fusion of protoplasts from two different varieties of plants to get hybrid protoplasts. It can be grown to form a new plant called somatic hybrids. E.g. Protoplast of tomato + protoplast of potato → pomato. 

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