Board exam focus — Strategies for Enhancement in Food Production (CBSE & HBSE)

CBSE emphasises plant breeding steps with specific variety names (Sonalika, IR-8, Himgiri), animal husbandry breeds, tissue culture techniques, and SCP with organisms. HBSE focuses on definitions, plant breeding steps, composite fish culture, apiculture, and SCP organisms with advantages.

Animal Husbandry

Animal Husbandry — Definition

Animal husbandry is the branch of agriculture concerned with the breeding, feeding, and care of farm animals to maximise their production of food products (milk, eggs, meat, etc.) and other useful products (wool, silk, honey).

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Cattle Farming (Dairy and Draught)

Aim: Increase milk production (dairy breeds), work capacity (draught breeds), or both (dual-purpose breeds).

Improvement methods:

1. Inbreeding: Mating of closely related individuals within same breed → increases homozygosity, helps fix desirable traits
2. Outbreeding: Mating between unrelated individuals:

• Outcrossing: Mating within breed but unrelated individuals
• Cross-breeding: Mating between different breeds (most important for commercial dairy)
• Interspecific hybridisation: Mating between different species (e.g., horse × donkey = mule; cow × bison = beefalo)

Important Indian Cattle Breeds:

Animal husbandry management:

• Clean housing; proper ventilation; clean water
• Balanced diet: Roughage + concentrates + mineral supplements + vitamins
• Regular veterinary care; vaccination; deworming

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Poultry Farming

Poultry includes: Chickens, ducks, turkeys, geese. Products: Eggs, meat, feathers.

Important breeds:

Poultry management:

• Layers (egg-laying hens): Need 14-16 hours light/day to maximise egg production; calcium-rich feed
• Broilers (meat chickens): High-protein diet; growth in ~6-7 weeks to market weight
• Regular vaccination against Newcastle disease, Marek's disease, avian influenza

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Apiculture (Bee Keeping)

Bee keeping is the maintenance of honey bee colonies for:

• Honey (food, medicine)
• Beeswax (cosmetics, candles, polish)
• Royal jelly (queen bee diet; health supplement)
• Propolis (resin-like substance; antimicrobial)
• Pollination services (most economically important!— ~80% of flowering crops need insect pollination)

Bee species used:

Flora and honey quality:

• The flora (flowering plants) in the area determines honey flavour, colour, and quality
• Khair flower honey, mustard honey, litchi honey — distinct flavours

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Fisheries and Aquaculture

Marine fisheries (Mariculture):

• Important marine fish: Hilsa, Sardine (pilchard), Bombay duck (Harpodon), Mackerel, Tuna, Catfish
• Important marine products: Prawns, Crabs, Lobsters, Oysters (also pearls)
• Technologies: Echo-sounder (fish location), satellite (sea surface temperature maps), modern fishing vessels

Freshwater aquaculture (Pisciculture):

• Important fish: Catla (Catla catla), Rohu (Labeo rohita), Mrigal (Cirrhinus mrigala), Silver carp, Grass carp, Common carp

Composite Fish Culture (Polyculture): Multiple fish species cultivated in one pond simultaneously:

• Select species that occupy different trophic levels/niches in the pond
• No competition; maximum utilisation of pond resources

Problem: Breeding seasons of Indian major carps often don't coincide in ponds → inject pituitary hormone extract (hypophysation) to stimulate breeding.

Blue Revolution: Focused development of fisheries and aquaculture (analogous to Green Revolution in agriculture).

Diagram Indicator: [Diagram of composite fish culture pond showing vertical zonation of 5-6 species at different depths (surface to bottom); AND table of bee species with honey yield comparison]

Plant Breeding

Plant Breeding — Definition

Plant breeding is the purposeful manipulation of plant species to create desired genotypes and phenotypes that are of benefit to humans. It aims to increase crop yield, improve nutritional quality, and develop resistance to biotic (pests/diseases) and abiotic (drought, salinity) stresses.

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Steps in Plant Breeding

Step 1: Collection of Germplasm (Variability)

• Collect maximum genetic diversity
• Sources: Wild relatives, local landraces (traditional varieties), heirloom varieties, related species
• Stored in germplasm banks / seed banks (NBPGR — National Bureau of Plant Genetic Resources, ICAR, India)
• Gene bank (germplasm bank): Repository of seeds, pollen, plant tissue representing genetic diversity

Step 2: Evaluation and Selection of Parents

• Screen the germplasm for the desired trait
• Identify superior parents with the required characteristics
• Phenotypic selection (for simply inherited traits) or progeny testing (for quantitative traits)

Step 3: Cross Hybridisation of Selected Parents

• Controlled crosses between selected parents (hand pollination after emasculation in bisexual plants)
• Emasculation: Removal of anthers from bisexual flowers to prevent self-fertilisation before controlled pollination
• Hybridisation: To combine desirable traits from different parents in one offspring

Step 4: Selection and Testing of Superior Recombinants

• F1 → F2 and further generations → select plants combining desired traits
• Process may take 8-10 years for self-pollinated crops
• Selection of pure-breeding lines that are homozygous for desired traits

Step 5: Testing, Release and Commercialisation

• Selected varieties tested in controlled conditions → then multi-location field trials
• Trials assess yield, disease resistance, quality, and regional adaptability
• Approved by government → released as a notified variety → commercial seed production

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Achievements of Plant Breeding: Green Revolution

Green Revolution (1960s-70s): Introduction of high-yielding varieties (HYVs) + irrigation + fertilisers + pesticides → dramatic increase in food production in India and developing countries.

Wheat varieties:

• Sonalika and Kalyan Sona: High-yielding dwarf wheat varieties developed by M.S. Swaminathan (India) using germplasm from Norman Borlaug (Mexico). Revolutionised wheat production in India.
• Norin-10: Dwarfing gene source (from Japan)
• Norman Borlaug: "Father of Green Revolution"; Nobel Peace Prize (1970)

Rice varieties:

• IR-8 (Miracle Rice): Developed by IRRI (International Rice Research Institute, Philippines, 1966); semi-dwarf, highly responsive to fertiliser; yield ~5× traditional varieties
• Jaya and Ratna: Indian high-yielding rice varieties developed from IR-8

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Disease Resistance Breeding

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Pest Resistance

• Pusa Sawani (bhindi): Resistant to shoot and fruit borer
• Jaya and Ratna rice: Resistant to pests

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Biofortification

Biofortification = development of crop varieties with higher levels of vitamins, minerals, or protein quality through conventional breeding or biotechnology.

Objectives:

1. Improve nutritional content
2. Address hidden hunger (micronutrient deficiency)
3. Improve protein quality and content

Examples:

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Hybrid Seeds and Heterosis

Heterosis (Hybrid vigour): F1 hybrids often show superior performance (yield, disease resistance) compared to either parent.

• Common in maize, sunflower, vegetables
• Disadvantage: F2 seeds lose heterosis → farmers must buy fresh F1 seeds each season (profitable for seed companies, costly for farmers)

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Mutation Breeding

Artificially induced mutations using mutagens:

• Physical mutagens: X-rays, gamma rays, UV radiation
• Chemical mutagens: EMS (ethyl methane sulfonate), nitrous acid

Example: Atomita-2 (rice variety) — developed using gamma rays → resistant to sheath blight + tolerant to salt and flooding.

Diagram Indicator: [Flowchart of 5 steps of plant breeding from germplasm collection to commercial release; AND diagram of emasculation showing removal of anthers from flower before hand pollination with pollen from desired father plant]

Single Cell Protein (SCP) and Tissue Culture

Single Cell Protein (SCP)

SCP refers to the use of microbial biomass (cells of microorganisms — bacteria, yeast, algae, fungi) as a protein-rich food or feed supplement.

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Organisms Used for SCP Production

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Advantages of SCP

1. High protein content (~50-70%) compared to conventional foods (meat ~15-25%, legumes ~20-25%)
2. Rapid growth: Doubling time of hours (bacteria) to days (algae); much faster than cattle or crops
3. Small land area required: Produced in bioreactors or ponds
4. Uses waste materials: Grow on industrial/agricultural waste (sewage, molasses, straw, methanol) → waste treatment + food production simultaneously
5. Year-round production: Not dependent on season or weather
6. Low fat, high protein — good nutritional profile

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Limitations of SCP

• High nucleic acid content (especially in bacteria and algae) → can cause gout (uric acid buildup) — requires processing
• Digestibility issues
• Consumer acceptance challenges (especially for human food)
• High initial capital costs for bioreactors

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Tissue Culture

Tissue culture is the growth of explants (small pieces of plant tissue/organs) in a sterile artificial nutrient medium under controlled conditions to produce:

• Callus → new plants (indirectly)
• Embryoids (directly)

Key Concepts:

Totipotency: The ability of a single plant cell to develop into a complete organism. Concept proposed by G. Haberlandt (1902); experimentally proved by F.C. Steward (1958) using carrot phloem cells → grew into complete carrot plants.

Explant: A small piece of plant tissue (leaf disc, shoot tip, root tip, embryo, endosperm) used as the starting material.

Callus: A mass of undifferentiated parenchymatous cells formed when explant is cultured on a medium with high auxin. The callus can:

• Be subcultured repeatedly
• Differentiate into shoots/roots when hormone ratio changed (organogenesis) or embryos (somatic embryogenesis)

Hormone ratios for organogenesis:

• High auxin : low cytokinin → root differentiation
• Low auxin : high cytokinin → shoot differentiation
• Equal auxin + cytokinin → callus growth (no differentiation)

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Applications of Tissue Culture

1. Micropropagation:

• Rapid clonal multiplication of plants
• Large number of genetically identical plants (somaclones) produced from a single plant
• Commercial uses: Orchids, ferns, banana, strawberry, potato, sugarcane, oil palm, rose
• One banana plantlet → 10,000 plants in 6 months

2. Somaclones: Plants produced via tissue culture that are genetically identical to the parent (clones of somatic cells).

3. Pathogen elimination:

• Meristem culture / Shoot tip culture: Meristematic cells (apical meristem) are virus-free even in infected plants
• Used to produce virus-free plants (crucial for seed potato, sugarcane, banana propagation)

4. Somatic Hybridisation (Protoplast Fusion):

• Protoplast = plant cell with cell wall removed (using cellulase + pectinase enzymes)
• Protoplasts from two different species fused using:
• PEG (polyethylene glycol) — chemical method
• Electrofusion (electric shock) — physical method
• Fused cell = cybrid (cytoplasmic hybrid) or somatic hybrid
• Example: Potato (Solanum tuberosum) + Tomato (Lycopersicum esculentum) → Pomato (somatic hybrid; viable but sterile — did not give potato tubers AND tomato fruits)

5. Embryo Rescue:

• Embryos from wide crosses (distantly related species) that would abort naturally → grown in culture → viable plants

6. Anther Culture:

• Anthers cultured → pollen grains develop into haploid plants (androgenesis)
• Haploid plants treated with colchicine (blocks spindle formation → prevents cell division → chromosomes double) → diploid, completely homozygous plants in one step
• Used for: rapid development of homozygous lines for plant breeding

Diagram Indicator: [Diagram showing tissue culture process: explant → callus (on high auxin medium) → shoot organogenesis (low auxin:high cytokinin) → root organogenesis (high auxin:low cytokinin) → complete plantlet → hardening → field planting; AND diagram of protoplast fusion showing removal of cell wall, mixing, PEG fusion, hybrid cell formation]

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Concept explanations, key formulas and definitions, fully solved examples and board-pattern practice questions for Strategies for Enhancement in Food Production.