Tamil Nadu HSE Second Year Agricultural Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cropping intensity

Percentage expression of how many times the net sown area is cropped in a year, calculated as total cropped area divided by net sown area multiplied by one hundred.

Land equivalent ratio

Sum of the ratios of intercrop yield to sole crop yield for each component species; a value above one shows intercropping uses resources more efficiently than sole cropping.

Cation exchange capacity

Total quantity of exchangeable cations a soil can hold, expressed in centimoles of charge per kilogram; higher clay and organic matter content generally raises the value.

Lime requirement

Amount of calcium carbonate needed to raise soil pH to a target level; it increases with soil clay content, organic matter and initial acidity.

Leaf area index

Dimensionless ratio of total leaf area of a crop canopy to the ground area it occupies; values between three and five are often optimal for field crops.

Vernalization

Low-temperature treatment during early growth that promotes or accelerates flowering in crops such as wheat, allowing them to complete their life cycle.

Duty of water

Volume of irrigation water needed per unit area over a base period, usually expressed as hectares irrigated per cubic metre per second of continuous discharge.

Fertigation

Application of soluble fertilizers through a drip or sprinkler irrigation system so that nutrients are delivered directly to the root zone with the irrigation water.

Economic threshold level

Pest population density at which control measures should be applied to prevent the pest from reaching the economic injury level and causing unacceptable loss.

Koch's postulates

Four criteria proving a microorganism causes a disease: constant association, isolation in pure culture, inoculation reproducing symptoms, and re-isolation of the same organism.

Apical dominance

Suppression of lateral bud growth by the terminal bud through auxin; removing the tip by pinching or pruning encourages branching in ornamental crops.

Controlled atmosphere storage

Post-harvest storage technique that lowers oxygen and raises carbon dioxide concentrations around produce to slow respiration and extend shelf life.

Gestation period of cattle

Duration of pregnancy from conception to calving, about 280 to 285 days in cattle and about 305 to 310 days in buffalo.

Colostrum

First milk secreted after calving, rich in immunoglobulins and antibodies; feeding it within the first hour of birth protects the newborn calf from infection.

Benefit-cost ratio

Ratio of total returns to total cost of an enterprise; a value greater than one indicates the enterprise is profitable at the prices used.

Diffusion of innovation

Process by which a new practice spreads among farmers through stages of knowledge, persuasion, decision, implementation and confirmation, with adopters classed from innovators to laggards.

Field capacity of machine

Area a farm machine can cover per unit time, calculated as implement width in metres multiplied by speed in kilometres per hour and divided by ten.

Wet basis moisture content

Mass of water in a produce sample expressed as a percentage of the total mass including water, commonly used in grain drying and storage calculations.

Instars of silkworm

Successive growth stages between moults in the silkworm larva; Bombyx mori passes through five instars, with the fifth consuming most of the leaf.

Pebrine disease

Silkworm disease caused by the protozoan Nosema bombycis, transmitted through eggs and causing mottled larvae and reduced cocoon production.

Composite fish culture

Pond culture system stocking several carp species with different feeding habits together so that food available at all depths and niches is used efficiently.

Hypophysation

Technique of inducing fish breeding by injecting pituitary gland extract or synthetic hormone into brood fish to trigger spawning under controlled conditions.

Agroforestry

Deliberate integration of trees with crops or livestock on the same land unit, often using nitrogen-fixing species to improve soil fertility and diversify income.

Social forestry

Management of trees on farmland, community land and roadside strips to meet local fuel, fodder and timber needs while protecting the environment.

Composite soil sample

Mixture of soil cores collected from several spots in a field in a zig-zag pattern, quartered to a representative subsample for laboratory analysis.

Germination percentage

Number of normal seedlings produced from a hundred seeds under prescribed test conditions, expressed as a percentage of the seeds tested.

Critical period of weed competition

Interval in the crop growth cycle during which weed competition causes the greatest yield loss, commonly the first thirty to forty-five days after sowing.

Fertilizer nutrient calculation

Dose of a fertilizer is found by multiplying the recommended nutrient rate by one hundred and dividing by the percentage nutrient content of that fertilizer.

Transpiration ratio

Mass of water transpired by a crop divided by mass of dry matter produced; a lower value indicates more efficient water use by the crop.

Delta of water

Total depth of irrigation water applied to a crop over its base period, usually expressed in metres or centimetres for irrigation planning.

Trichoderma viride

Antagonistic fungus used as a biocontrol agent against soil-borne pathogens, applied as seed treatment or enriched compost to protect crop roots.

Poultry incubation period

Time from setting eggs to hatching under incubation, about twenty-one days for chicken eggs and twenty-eight days for duck eggs.