BSEB Inter Agriculture flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Cropping intensity
- The percentage of net sown area cropped more than once in a year, calculated as total cropped area divided by net sown area multiplied by 100.
- Land equivalent ratio
- A measure of intercropping advantage equal to the sum of each component's intercrop yield divided by its sole-crop yield; a value above one indicates benefit.
- Growing degree days
- The accumulated heat units above a base temperature, calculated from daily maximum and minimum temperatures, used to predict crop development stages.
- Critical weed competition period
- The early crop growth window, often the first thirty to forty-five days after sowing, during which weed competition causes the greatest and irreversible yield loss.
- Bulk density
- The mass of oven-dry soil divided by its total volume, expressed in grams per cubic centimetre; it indicates compaction and pore space.
- Cation exchange capacity
- The total quantity of exchangeable cations a soil can hold, expressed in centimoles of charge per kilogram; clay and organic matter raise it.
- Law of the minimum
- The principle that crop yield is limited by the essential nutrient in shortest supply, so balanced fertilization is needed rather than excess of one nutrient.
- Soil pH
- A measure of soil acidity or alkalinity on a scale of zero to fourteen; most field crops grow best between pH six and seven point five.
- Heterosis
- The superiority of a hybrid offspring over its parents in vigour, yield or other traits; it is most pronounced in cross-pollinated crops.
- Backcross breeding
- A method that repeatedly crosses a hybrid back to a recurrent parent to transfer one desirable gene, such as disease resistance, while restoring the parent's type.
- Male sterility
- The inability of a plant to produce viable pollen; cytoplasmic and genetic forms allow hybrid seed production without hand emasculation.
- Test cross
- A cross of an individual of unknown genotype with a homozygous recessive parent; a one-to-one ratio in offspring reveals heterozygosity.
- Tetrazolium test
- A rapid viability test in which living embryo tissue reduces tetrazolium salt to a red stain, while dead tissue remains unstained.
- Seed purity
- The percentage of pure seed of the stated kind in a sample, calculated as pure seed weight divided by total sample weight multiplied by one hundred.
- Seed dormancy
- A state in which viable seeds fail to germinate even under favourable conditions; it can be broken by scarification, cold stratification or gibberellic acid.
- Air layering
- A vegetative propagation method in which a stem is girdled and wrapped with moist medium to induce roots before separation; used in guava and litchi.
- Pruning
- The deliberate removal of plant parts to regulate canopy shape, light penetration and fruit quality; heading back and thinning out are basic cuts.
- Ethylene
- A gaseous plant hormone that accelerates ripening and senescence; it is used commercially to ripen fruit and must be managed during storage.
- Economic threshold level
- The pest population density at which control measures are justified to prevent the pest from causing economic loss.
- Koch's postulates
- A set of steps proving a microorganism causes a disease: isolation, pure culture, inoculation into a healthy host, and re-isolation of the same organism.
- Integrated pest management
- A strategy combining cultural, mechanical, biological and chemical methods, using pesticides only when thresholds are exceeded.
- Colostrum
- The first milk secreted after calving, rich in antibodies and nutrients; feeding it to the newborn calf within the first hour provides passive immunity.
- Balanced ration
- A feed mixture supplying all required nutrients in correct proportion and quantity for a specific animal over twenty-four hours.
- Crossbreeding
- The mating of animals of different breeds to combine desirable traits and exploit hybrid vigour, commonly used in dairy cattle improvement.
- Benefit–cost ratio
- The present value of benefits divided by the present value of costs; a ratio greater than one indicates a profitable investment.
- Law of diminishing returns
- The principle that adding more of one input while others stay fixed eventually yields smaller additional output per unit of input.
- Adoption process
- The mental sequence a farmer passes through before adopting a practice: awareness, interest, evaluation, trial and finally adoption.
- Farm records
- Systematic written accounts of physical and financial farm activities, used for planning, credit access and measuring profitability.
- Field efficiency
- The ratio of actual field capacity to theoretical field capacity, expressed as a percentage, reflecting time lost to turns, adjustments and refilling.
- Drip irrigation
- A method delivering water slowly and directly to the root zone through emitters, saving water and reducing weed growth and foliar disease.
- Agroforestry
- The deliberate integration of trees with crops and livestock on the same land unit to diversify income and improve soil and microclimate.
- Conservation agriculture
- A farming system based on minimum soil disturbance, permanent soil cover and crop diversification to protect soil and water resources.