Maharashtra HSC Agricultural Science & Technology cheat sheet

C3 plants fix CO2 via RuBisCO into 3-phosphoglycerate; C4 plants first fix CO2 into oxaloacetate (4-carbon) in mesophyll cells, reducing photorespiration at high temperature.

Net assimilation rate (NAR) = (W2 − W1)(ln L2 − ln L1) / [(t2 − t1)(L2 − L1)], where W = dry weight and L = leaf area.

Crop growth rate (CGR) = (W2 − W1) / (t2 − t1), expressed as g m⁻² day⁻¹; it integrates NAR and leaf area index.

Leaf area index (LAI) = total leaf area / ground area; most field crops peak near LAI 3–5 before self-shading lowers NAR.

Seed germination requires water, oxygen, and a suitable temperature; the three-phase pattern is imbibition, lag phase (metabolic preparation), and radicle emergence.

Vernalization is low-temperature promotion of flowering (e.g., wheat); photoperiod response classifies crops as long-day, short-day, or day-neutral.

Kharif crops are sown with monsoon onset (June–July) and harvested in autumn (rice, cotton, sorghum); rabi crops are sown October–November and harvested spring (wheat, chickpea, mustard).

Seed rate (kg/ha) = (desired plant population per ha × test weight in g) / (1000 × germination % × purity %), with field establishment factor applied.

Soil texture classes follow the USDA triangle defined by % sand, % silt, and % clay; loam is roughly 40% sand, 40% silt, 20% clay.

Bulk density = oven-dry soil mass / total volume; particle density of mineral soil is about 2.65 g/cm³, so porosity % = (1 − bulk density/2.65) × 100.

Soil pH affects nutrient availability: most macronutrients are optimally available near pH 6.0–7.0; iron, manganese, and zinc become less available as pH rises above 7.

Cation exchange capacity (CEC) is measured in cmol(+) kg⁻¹; base saturation % = (sum of exchangeable bases / CEC) × 100.

Liebig's law of the minimum: yield is limited by the nutrient in shortest supply relative to crop requirement, not by total nutrient quantity.

Fertilizer dose for a nutrient = (recommended nutrient kg/ha × 100) / % nutrient content of the fertilizer; urea is 46% N, DAP 18% N and 46% P2O5, MOP 60% K2O.

Nitrogen fixation by Rhizobium in legume root nodules is symbiosis-specific; inoculation fails if the wrong host-specific strain is used.

Soil organic carbon improves aggregate stability, water-holding capacity, and CEC; the carbon:nitrogen ratio of residues near 25:1 favours net mineralization.

Economic threshold level (ETL) is the pest density at which control measures should begin to prevent the pest from reaching the economic injury level (EIL).

Insect mouthparts determine control choice: chewing insects (caterpillars, beetles) suit stomach poisons; sucking insects (aphids, hoppers) suit systemic or contact insecticides.

Integrated pest management hierarchy: cultural, mechanical, biological, and chemical methods, with chemicals used last and rotated by mode of action to delay resistance.

Koch's postulates establish a pathogen as the cause of a disease: consistent association, isolation in pure culture, reinoculation causing symptoms, and re-isolation.

Disease triangle: disease occurs when a susceptible host, a virulent pathogen, and favourable environment coincide over time; removing any leg reduces epidemic.

Fungicide groups by site of action include multi-site protectants (e.g., mancozeb, copper) and single-site systemics (e.g., triazoles, strobilurins); resistance risk is higher for single-site products.

Pesticide label calculation: quantity of commercial product = (desired active ingredient dose × spray volume) / concentration of active ingredient in the product.

Biological control agents include Trichoderma for soilborne fungal pathogens, Bacillus thuringiensis against lepidopteran larvae, and Trichogramma egg parasitoids.

Crossbreeding of indigenous cattle with exotic breeds (e.g., Holstein Friesian, Jersey) aims at heterosis for milk yield while retaining tropical adaptation.

Colostrum is the first milk after calving, rich in immunoglobulins; calves should receive it within the first 2 hours because gut absorption of antibodies declines rapidly.

Milk composition of cow milk is approximately 87% water, 3.5% fat, 3.3% protein, 4.6% lactose, and 0.7% minerals; buffalo milk is higher in fat.

Clean milk production requires udder washing, discarding foremilk, sanitized utensils, and rapid cooling to 4 °C to slow bacterial growth.

Breeding soundness in cattle: estrus cycle length is about 21 days, gestation about 280–285 days in cattle and about 305–310 days in buffalo.

Feed formulation uses a concentrate mixture balanced for crude protein and total digestible nutrients, with roughage:concentrate ratio adjusted to production level.

Mastitis is an inflammation of the udder, commonly bacterial; the California Mastitis Test screens for elevated somatic cell count in quarter milk.

Vaccination schedules for cattle include foot-and-mouth disease, haemorrhagic septicaemia, and black quarter; timing follows local epidemiological advice.

Draft of a tillage implement depends on soil resistance, implement width, and depth; draft (kgf) ≈ soil resistance (kgf/cm²) × width (cm) × depth (cm).

Field capacity = area covered per unit time; field efficiency % = (effective field capacity / theoretical field capacity) × 100.

Theoretical field capacity (ha/h) = (implement width in m × forward speed in km/h) / 10.

Tractor power take-off (PTO) power is rated at 540 rpm standard; implement matching requires PTO power above the implement's peak draft power demand.

Seed drill calibration: seed rate is adjusted by varying the metering opening and ground-wheel gearing; check by collecting seed over a known area or revolutions.

Irrigation water requirement = crop evapotranspiration − effective rainfall; drip irrigation typically achieves 85–95% application efficiency versus 60–75% for surface flooding.

Sprinkler system design uses precipitation rate = (discharge per nozzle × number of nozzles) / wetted area, compared with soil infiltration rate to avoid runoff.

Grain moisture content on a wet basis = (water mass / total wet mass) × 100; dry basis uses water mass / dry matter mass × 100.

Gross income = yield × price; net income = gross income − total cost (variable cost + fixed cost).

Gross margin = gross income − variable costs; it excludes fixed costs and is used to compare enterprise options.

Benefit-cost ratio = present value of benefits / present value of costs; a ratio above 1 indicates the project is viable at the chosen discount rate.

Net present value (NPV) = sum of discounted net cash flows; accept projects with NPV > 0; internal rate of return (IRR) is the discount rate giving NPV = 0.

Farm size classes in Maharashtra are defined by landholding, and marginal and small holdings dominate the total number of operational holdings.

Cost concepts: cost A1 covers paid-out costs; cost A2 adds rent for owned land; cost C includes imputed value of family labour and interest on owned capital.

Law of diminishing marginal returns: as a variable input is added to fixed inputs, marginal product eventually declines; optimum input use is where marginal value product equals marginal factor cost.

Marketing channels and price spread: price spread = consumer price − producer price; reducing intermediaries raises the producer's share in the consumer rupee.

Propagation: sexual (seed) propagation suits variability-tolerant crops; vegetative methods (cutting, layering, grafting, budding) preserve clonal characteristics.

Grafting success requires cambial contact between scion and rootstock, compatible species, and a rapid union before desiccation.

Climacteric fruits (banana, mango, tomato) show a respiration peak and ethylene burst at ripening; non-climacteric fruits (citrus, grape) do not ripen after harvest.

Controlled atmosphere storage lowers oxygen (typically 2–5%) and raises carbon dioxide to slow respiration, extending storage life of apples and other produce.

Pre-cooling removes field heat quickly; the half-cooling time is the period needed to reduce the temperature difference by half.

Chilling injury occurs in tropical produce stored below about 10–13 °C; symptoms include pitting, browning, and failure to ripen.

Processing: jam requires about 65–68% total soluble solids for gel formation; blanching inactivates enzymes that cause browning and off-flavours.

Drying rate in a falling-rate period is controlled by internal moisture diffusion; the critical moisture content marks the end of the constant-rate phase.

Extension teaching methods divide into individual (farm visit, telephone), group (demonstration, field day), and mass (radio, print, digital) contacts.

Adoption of an innovation follows stages: awareness, interest, evaluation, trial, and adoption; adopters are classified as innovators through laggards.

Diffusion of innovations: the adoption curve is roughly normal, with innovators about 2.5%, early adopters about 13.5%, and the majority the remainder.

A demonstration plot compares a recommended practice against the farmer's practice under similar conditions to show measurable yield or income difference.

Participatory rural appraisal uses local knowledge and ranking tools to identify problems, priorities, and feasible interventions with the community.

Krishi Vigyan Kendra (KVK) is a district-level technology-transfer institution for on-farm testing, frontline demonstration, and training.

Feedback from farmers is essential for refining recommendations; two-way communication beats one-way message delivery in adoption.

Greenhouse gases include CO2, CH4, N2O, and water vapour; methane has far higher global warming potential per molecule than CO2 over a 20-year horizon.

Eutrophication results from excess nitrogen and phosphorus in water, causing algal blooms, oxygen depletion, and fish kills.

Biological oxygen demand (BOD) measures oxygen consumed by microbes decomposing organic matter; a higher BOD indicates more organic pollution.

Pesticide residue risks are reduced by respecting pre-harvest intervals and rotating modes of action; bioaccumulation occurs in lipophilic compounds.

Air pollution from crop residue burning releases particulate matter and CO2; alternatives include residue incorporation and use as fodder or fuel.

Salinity and waterlogging in irrigated lands result from rising water tables and poor drainage; gypsum application helps reclaim sodic soils.

Conservation of biodiversity in agricultural landscapes depends on habitat patches, field margins, and reduced pesticide pressure on pollinators.

Sustainable agriculture balances productivity, profitability, and resource conservation; indicators include soil organic matter, water use efficiency, and biodiversity.

Crop rotation breaks pest and disease cycles and improves nutrient balance; legume inclusion adds biologically fixed nitrogen to the system.

Conservation tillage leaves at least 30% of the soil surface covered by residue, reducing erosion and improving infiltration.

Integrated nutrient management combines organic sources (farmyard manure, green manure, compost) with mineral fertilizers to match crop demand.

Water harvesting structures recharge groundwater and provide supplemental irrigation; check dams and farm ponds are common on-farm options.

Agroforestry systems (alley cropping, boundary planting) provide fuel, fodder, and timber while improving soil and microclimate.

Soil erosion control: contour bunding, terracing, and vegetative barriers reduce slope length and runoff velocity.

A business plan states the product, market, production process, costs, and expected returns; it should include a break-even calculation.

Break-even quantity = fixed costs / (selling price per unit − variable cost per unit).

Value addition through grading, packaging, processing, or branding raises the producer's share of the final consumer price.

Market linkages such as farmer producer organizations (FPOs) and cooperatives improve bargaining power and access to inputs and credit.

Working capital covers day-to-day expenses; fixed capital covers land, buildings, and machinery; both must be estimated separately.

Credit appraisal assesses repayment capacity using net farm income and debt-service coverage; subsidized institutional credit reduces interest burden.

Direct marketing and e-commerce platforms let producers shorten the supply chain; quality assurance and traceability build buyer confidence.

Risk management tools include crop insurance, diversification, contract farming, and forward price arrangements.