Maharashtra HSC Agricultural Science & Technology flashcards

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

C4 photosynthesis advantage

C4 plants fix CO2 into a four-carbon acid in mesophyll cells before Calvin cycle fixation, concentrating CO2 around RuBisCO. This cuts photorespiration and boosts water and nitrogen use efficiency at high temperature.

Leaf area index

Total leaf area divided by the ground area beneath the canopy. It indicates light interception; most field crops reach an optimum near 3 to 5 before self-shading reduces net assimilation.

Vernalization

Low-temperature treatment that promotes flowering in crops such as wheat. It converts vegetative growth to reproductive growth, and the requirement differs among varieties and sowing dates.

Kharif versus rabi

Kharif crops are sown with the monsoon and harvested in autumn, such as rice and cotton. Rabi crops are sown in winter and harvested in spring, such as wheat and chickpea.

Seed rate formula

Seed rate in kg per hectare equals desired plant population multiplied by test weight in grams, divided by 1000 times germination percentage times purity percentage.

Soil bulk density

Oven-dry soil mass divided by total soil volume, expressed in g per cubic centimetre. It indicates compaction; higher density means lower porosity and poorer root penetration.

Cation exchange capacity

The total exchangeable cations a soil can hold, expressed in cmol positive charge per kilogram. Clay and organic matter raise CEC and improve nutrient retention.

Liebig's law of the minimum

Crop yield is limited by the nutrient in shortest supply relative to crop requirement, not by the total amount of nutrients present. Correcting that deficiency raises yield.

Urea nitrogen content

Urea contains about 46 percent nitrogen, the highest among common solid nitrogen fertilizers. Fertilizer quantity needed equals recommended nutrient multiplied by 100 divided by percent nutrient.

Economic threshold level

The pest population density at which control should begin to prevent the pest from reaching the economic injury level. It avoids unnecessary pesticide applications.

Disease triangle

A plant disease develops when a susceptible host, a virulent pathogen, and a favourable environment coincide. Removing any one of the three components prevents or reduces the epidemic.

Koch's postulates

Criteria linking a pathogen to a disease: consistent association, isolation in pure culture, reinoculation reproducing symptoms, and re-isolation of the same organism from the diseased host.

Bacillus thuringiensis

A soil bacterium used as a biological insecticide. Its protein crystals are toxic to lepidopteran larvae after ingestion, and it has low toxicity to mammals and beneficial insects.

Colostrum feeding

The first milk after calving, rich in antibodies. Calves should receive it within about two hours because the gut's ability to absorb intact immunoglobulins declines rapidly.

Clean milk production

Milk hygiene practices including udder washing, discarding foremilk, sanitized utensils, and rapid cooling to about 4 degrees Celsius, which slows bacterial multiplication and preserves quality.

Estrus cycle length

The interval between successive heats in cattle, about 21 days. Gestation averages roughly 280 to 285 days in cattle and 305 to 310 days in buffalo.

Mastitis

Inflammation of the udder, usually caused by bacterial infection. Somatic cell count rises in milk, and the California Mastitis Test is a quick herd screening tool.

Theoretical field capacity

Implement width in metres multiplied by forward speed in kilometres per hour, divided by ten, giving hectares per hour. Actual capacity is lower because of turning and loading time.

Field efficiency

Effective field capacity divided by theoretical field capacity, expressed as a percentage. It accounts for turning, refilling, and other non-productive time during field operations.

Drip irrigation efficiency

Drip systems apply water near the root zone and typically achieve 85 to 95 percent application efficiency, compared with 60 to 75 percent for surface flooding.

Grain moisture wet basis

Water mass divided by total wet grain mass, multiplied by 100. Dry basis instead divides water mass by dry matter mass, giving a higher percentage for the same sample.

Gross margin

Gross income minus variable costs for an enterprise. Fixed costs are excluded, so gross margin compares enterprises on returns to land and fixed resources.

Benefit-cost ratio

Present value of benefits divided by present value of costs. A ratio above one indicates the project returns more than the discount rate used in the analysis.

Net present value

The sum of discounted net cash flows over a project's life. A positive value means returns exceed the chosen discount rate; internal rate of return is where it equals zero.

Law of diminishing returns

Adding more of a variable input to fixed inputs eventually lowers marginal product. Optimum use occurs where marginal value product equals marginal factor cost.

Climacteric fruit

Fruit that shows a respiration peak and ethylene burst at ripening, such as banana, mango, and tomato. It continues ripening after harvest, unlike non-climacteric citrus and grape.

Controlled atmosphere storage

Storage with reduced oxygen, typically 2 to 5 percent, and elevated carbon dioxide. This slows respiration and ethylene action, extending storage life of apples and similar produce.

Chilling injury

Damage to tropical produce stored below about 10 to 13 degrees Celsius. Symptoms include surface pitting, browning, and failure to ripen normally after transfer to warmer conditions.

Adoption stages

The sequence an individual follows for an innovation: awareness, interest, evaluation, trial, and adoption. Extension methods differ in effectiveness at each stage.

Participatory rural appraisal

A set of participatory tools using local knowledge, ranking, and mapping to identify community problems and priorities. It supports planning of extension programmes with farmers.

Biological oxygen demand

Oxygen consumed by microorganisms decomposing organic matter in water, measured over a set period. Higher values indicate greater organic pollution and lower dissolved oxygen.

Conservation tillage

Tillage that leaves at least 30 percent of the soil surface covered by crop residue. It reduces erosion, conserves moisture, and improves infiltration and soil organic matter.

Break-even quantity

Fixed costs divided by the difference between selling price per unit and variable cost per unit. It is the output level at which total revenue equals total cost.