1000 Most Important Agronomy MCQs with Explanation for ICAR JRF, NET, AFO & All Agriculture Exams
“Sulfonylurea” herbicides act by inhibiting which enzyme? a) EPSPS synthase b) Acetolactate synthase (ALS) c) Acetyl CoA carboxylase (ACCase) d) Protoporphyrinogen oxidase
Answer: b) Acetolactate synthase (ALS)
Explanation: Sulfonylurea herbicides (metsulfuron, sulfosulfuron) inhibit acetolactate synthase (ALS), an enzyme essential for branched-chain amino acid (valine, leucine, isoleucine) synthesis. This is a high-frequency question in ASRB NET and ICAR JRF exams.
The maximum limit per borrower in the agriculture sector under Priority Sector Lending (PSL) by banks (excluding NBFC-MFIs) is: a) ₹5 lakh b) ₹10 lakh c) ₹15 lakh d) ₹20 lakh
Answer: c) ₹15 lakh
*Explanation: The maximum limit per borrower in the agriculture sector under Priority Sector Lending by banks (excluding NBFC-MFIs) is ₹15 lakh. This question appeared in IBPS AFO memory-based papers and tests knowledge of agricultural credit policies .*
In the cost concept A2+FL, what does “FL” indicate? a) Farm labor b) Family labor (imputed value of family labor) c) Fixed land d) Fertilizer and lime
Answer: b) Family labor (imputed value of family labor)
*Explanation: In agricultural cost concepts, A2+FL includes actual paid-out costs (A2) plus the imputed value of family labor (FL). This is used by CACP for MSP calculations. This question appeared in IBPS AFO exams .*
The largest producer of spices in India is: a) Gujarat b) Madhya Pradesh c) Andhra Pradesh d) Kerala
Answer: c) Andhra Pradesh
Explanation: Andhra Pradesh is the largest producer of spices in India by volume, particularly red chili. This question appeared in UPPCS (Mains) 2012 and is frequently asked in state PSC exams .
“Bispyribac-sodium” is a herbicide used for: a) Pre-emergence weed control in wheat b) Post-emergence weed control in rice c) Pre-plant incorporation in soybean d) Perennial weed control in sugarcane
Answer: b) Post-emergence weed control in rice
Explanation: Bispyribac-sodium is an ALS inhibitor herbicide widely used for post-emergence control of grasses, sedges, and broadleaf weeds in direct-seeded and transplanted rice. This is frequently tested in weed management sections.
Which of the following is a hybrid variety of apple developed by crossing Red Delicious × Ambri? a) Sunheri b) Lal Ambri c) Ambroyal d) Chaubatia Anupam
Answer: b) Lal Ambri
Explanation: Lal Ambri is a hybrid apple variety developed by crossing Red Delicious × Ambri. It is colorful, sweet, and has good shelf life. This question appeared in IBPS AFO exams and tests horticulture knowledge .
The states accounting for more than half of India’s total rice production are: a) West Bengal, Punjab, Tamil Nadu, Odisha b) West Bengal, Uttar Pradesh, Punjab, Andhra Pradesh c) Punjab, Andhra Pradesh, Bihar, Odisha d) Uttar Pradesh, West Bengal, Chhattisgarh, Assam
Answer: b) West Bengal, Uttar Pradesh, Punjab, Andhra Pradesh
Explanation: These four states together account for more than half of India’s total rice production. This question appeared in UP (Spl) (Pre) 2009 and tests knowledge of crop geography .
“Journal of Plant Nutrition” is published by: a) Indian Society of Soil Science b) American Society of Agronomy c) Taylor and Francis Limited d) Oxford Academic Press
Answer: c) Taylor and Francis Limited
Explanation: The Journal of Plant Nutrition is published by Taylor and Francis Limited. This type of question tests awareness of scientific publications and appears in ICAR JRF and ASRB NET exams .
In which type of demonstration is the method shown to farmers (e.g., broadcasting, grafting, seed treatment) to explain new techniques? a) Frontline demonstration b) Method demonstration c) Result demonstration d) Farm and home visit
Answer: b) Method demonstration
Explanation: Method demonstration shows farmers HOW to do something (techniques like grafting, seed treatment), while result demonstration shows the OUTCOME/benefits. This question appeared in IBPS AFO exams and tests extension education knowledge .
“Synergism” in herbicide combinations means: a) Effect equal to sum of individual effects b) Effect less than sum of individual effects c) Effect greater than sum of individual effects d) No interaction between herbicides
Answer: c) Effect greater than sum of individual effects
*Explanation: Synergism occurs when herbicide combinations produce greater weed control than expected from additive effects of individual herbicides (1+1 > 2). This is a key concept in weed management frequently tested in ASRB NET.*
Which of the following statements is TRUE about the Kisan Credit Card (KCC) Scheme limit? a) Scale of finance × area cultivated b) Scale of finance × area cultivated + 10% for post-harvest expenses + 20% for farm asset maintenance + crop insurance c) Scale of finance only d) 10% of land value
Answer: b) Scale of finance × area cultivated + 10% for post-harvest expenses + 20% for farm asset maintenance + crop insurance
*Explanation: The KCC limit includes: scale of finance for the crop × extent of area cultivated + 10% of limit towards post-harvest expenses + 20% of limit towards repairs/maintenance of farm assets + crop insurance. This detailed question appeared in IBPS AFO exams .*
Which microorganism or biopesticide shows symptoms similar to “caterpillar wilt” on plants? a) Bacillus thuringiensis b) Nuclear Polyhedrosis Virus (NPV) c) Beauveria bassiana d) Trichoderma viride
Answer: b) Nuclear Polyhedrosis Virus (NPV)
Explanation: NPV causes “wilt disease” in caterpillars – infected larvae become lethargic, stop feeding, and their bodies liquefy, hanging in an inverted “V” shape. This symptom is characteristic of viral infection. This appeared in IBPS AFO exams .
“Peat soils” are characterized by: a) High sand content b) High organic content and humus c) High calcium carbonate d) High salt content
Answer: b) High organic content and humus
Explanation: Peat soils (Histosols) contain more than 20% organic matter and are formed in waterlogged conditions with slow decomposition. This question appeared in IBPS AFO exams and tests soil classification knowledge .
In soil, both organic and inorganic colloids suspended in water carry which type of charge? a) Positive b) Negative c) Neutral d) Alternating
Answer: b) Negative
Explanation: Soil colloids (both organic humus and inorganic clay minerals) predominantly carry negative charges, which attract and hold positively charged ions (cations) like Ca²⁺, Mg²⁺, K⁺, NH₄⁺. This is fundamental to cation exchange capacity (CEC). This appeared in IBPS AFO exams .
The irradiation amount required (in kGy) to stop sprouting in potato and reduce solanine production is: a) 0.01 kGy b) 0.03 kGy c) 0.10 kGy d) 0.25 kGy
Answer: b) 0.03 kGy
*Explanation: A low dose of 0.03 kGy (30 Gy) is sufficient to inhibit sprouting in potatoes, which also reduces solanine (toxic glycoalkaloid) production during storage. This question appeared in IBPS AFO exams and tests post-harvest technology knowledge .*
For artificial insemination (AI), semen after equilibration with glycerol is stored at -196°C using: a) Liquid nitrogen b) Liquid helium c) Dry ice d) Refrigerated ice
Answer: a) Liquid nitrogen
*Explanation: Frozen semen for AI is stored at -196°C in liquid nitrogen (LN₂) containers. Glycerol is used as a cryoprotectant during freezing. This question appeared in IBPS AFO exams and tests animal reproduction knowledge .*
“Savannah” vegetation refers to: a) Dense tropical forests b) Woodland and trees widely spaced, covered by grasses in hot climate c) Coniferous forests d) Mangrove swamps
Answer: b) Woodland and trees widely spaced, covered by grasses in hot climate
Explanation: Savannah is a grassland ecosystem characterized by widely spaced trees with a continuous grass understory, found in hot, seasonally dry climates. This question appeared in IBPS AFO exams .
“Allelopathy” was first scientifically described by: a) Hans Molisch (1937) b) Rice (1984) c) Muller (1966) d) Whittaker (1970)
Answer: a) Hans Molisch (1937)
*Explanation: Austrian scientist Hans Molisch coined the term “allelopathy” in 1937 from Greek words “allelon” (mutual) and “pathos” (harm/suffering), referring to chemical interactions between plants.*
The advanced stage of gully erosion where larger portions of soil are transported, common in alluvial soils, is called: a) Sheet erosion b) Rill erosion c) Ravine erosion d) Splash erosion
Answer: c) Ravine erosion
Explanation: Ravine erosion is the advanced stage of gully erosion characterized by deep, wide, and branched channels. It’s common in alluvial soils (Chambal ravines). Sheet, rill, and splash are earlier stages. This appeared in IBPS AFO exams .
What is the fat content present in double-toned milk? a) 1.5% b) 2.0% c) 3.0% d) 4.5%
Answer: a) 1.5%
*Explanation: Double-toned milk contains 1.5% fat and 9.0% SNF (Solids-Not-Fat). Toned milk (3% fat) and standardized milk (4.5% fat) have different compositions. This question appeared in IBPS AFO exams and tests dairy science knowledge .*
Which nutrient is essential for eggshell formation in poultry? a) Phosphorus b) Calcium c) Magnesium d) Iron
Answer: b) Calcium
*Explanation: Calcium is essential for eggshell formation. A laying hen requires 4-5 g of calcium daily, primarily as calcium carbonate for shell formation. Deficiency causes thin-shelled or shell-less eggs. This appeared in IBPS AFO exams .*
“Heterozygous” individuals phenotypically distinguishable from homozygous types is an example of: a) Complete dominance b) Incomplete dominance c) Co-dominance d) Epistasis
Answer: b) Incomplete dominance
Explanation: In incomplete dominance, heterozygotes show an intermediate phenotype distinguishable from both homozygotes (e.g., pink flowers in snapdragon from red × white cross). This appeared in IBPS AFO exams and tests genetics basics .
What is the correct time for harvesting Button mushrooms? a) When cap opens fully b) When mushroom attains egg/button stage c) When veil breaks d) When pileus expands
Answer: b) When mushroom attains egg/button stage
Explanation: Button mushrooms (Agaricus bisporus) are harvested at the button stage when the cap is still closed and mushroom is egg-shaped. This ensures best quality and shelf life. This appeared in IBPS AFO exams .
GMO food developed using genetic engineering or containing microorganisms is classified as: a) Organic food b) Novel food c) Conventional food d) Functional food
Answer: b) Novel food
*Explanation: Novel foods are foods or food ingredients that have not been significantly consumed by humans before a certain date (1997 in EU) and include GMOs, foods with new molecular structure, or those from new sources/processes. This appeared in IBPS AFO exams .*
What are the symptoms of Brucellosis disease in goats? a) High fever and nasal discharge b) Abortion in late pregnancy c) Diarrhea and dehydration d) Skin lesions
Answer: b) Abortion in late pregnancy
Explanation: Brucellosis in goats (caused by Brucella melitensis) primarily causes abortion in late pregnancy, along with retained placenta and reduced milk yield. It’s a zoonotic disease. This appeared in IBPS AFO exams .
The total depth of water required by a crop during its entire growing period to mature is technically called: a) Duty b) Delta c) Base period d) Kor depth
Answer: b) Delta
Explanation: Delta (Δ) is the total depth of water (in cm or m) required by a crop during its entire growing period from sowing to harvest. It includes water for evapotranspiration, puddling (for rice), leaching requirements, and other losses. This is a fundamental concept frequently tested in irrigation water management sections of ASRB NET and ICAR JRF exams .
The “duty” of water is expressed as: a) Depth of water in cm b) Discharge in cumecs c) Area irrigated per cumec of water (hectares/cumec) d) Volume of water in cubic meters
Answer: c) Area irrigated per cumec of water (hectares/cumec)
*Explanation: Duty of water is the relationship between the area irrigated (in hectares) and the continuous flow of water (in cumecs) required throughout the crop growth period. It is expressed as hectares per cumec. For example, if 1 cumec of water flowing continuously throughout the base period irrigates 100 hectares, the duty is 100 hectares/cumec .*
The “base period” for a crop is defined as: a) Total crop growth period from sowing to harvest b) Time from first to last irrigation c) Time from sowing to maturity when water is supplied through irrigation d) Time between two consecutive irrigations
Answer: c) Time from sowing to maturity when water is supplied through irrigation
*Explanation: Base period (B) is the time duration (in days) from the first watering at the time of sowing to the last watering before harvest when water is supplied through irrigation. It does not include the period when crop depends on rainfall. This concept is critical for calculating delta using the formula: Δ = (8.64 × B × Duty) / Area .*
The relationship between duty (D), delta (Δ), and base period (B) is given by: a) Δ = (8.64 × B) / D b) Δ = (B × D) / 8.64 c) Δ = (8.64 × D) / B d) Δ = (B × 864) / D
Answer: a) Δ (in meters) = (8.64 × B) / D
*Explanation: The standard formula relating delta (Δ in meters), duty (D in hectares/cumec), and base period (B in days) is: Δ = (8.64 × B) / D. This is derived from volume conservation: 1 cumec flowing for B days irrigates D hectares to a depth Δ. The constant 8.64 comes from converting cumec-days to cubic meters .*
The “kor watering” refers to: a) Last irrigation before harvest b) First irrigation after sowing c) Irrigation during flowering stage d) Pre-sowing irrigation
Answer: b) First irrigation after sowing
Explanation: Kor watering (also called “pallavi watering” in some regions) is the first irrigation given to a crop after sowing. It is critical for germination and establishment. The depth of water required for kor watering is called “kor depth,” and the corresponding base period is “kor period.” This is frequently tested in state agriculture officer exams .
The moisture content at which plants permanently wilt and cannot recover even if placed in a saturated atmosphere is called: a) Field capacity b) Permanent wilting point c) Available water d) Saturation point
Answer: b) Permanent wilting point
Explanation: Permanent wilting point (PWP) is the soil moisture content at which plants wilt and cannot recover turgidity even when placed in a saturated atmosphere. It occurs at approximately 15 atmospheres (1.5 MPa) tension. At this point, water is held so tightly by soil particles that roots cannot extract it. This is a standard question in irrigation scheduling sections .
The “field capacity” of a soil is defined as: a) Maximum water holding capacity b) Water content after gravitational drainage has ceased (2-3 days after irrigation/rain) c) Water content at permanent wilting point d) Water content at saturation
Answer: b) Water content after gravitational drainage has ceased (2-3 days after irrigation/rain)
*Explanation: Field capacity is the amount of water held in soil after excess gravitational water has drained away and the rate of downward movement has materially decreased, usually 2-3 days after rain or irrigation. It represents the upper limit of available water for plants .*
The available soil moisture for plant growth is the difference between: a) Saturation capacity and field capacity b) Field capacity and permanent wilting point c) Saturation capacity and permanent wilting point d) Hygroscopic coefficient and field capacity
Answer: b) Field capacity and permanent wilting point
Explanation: Available soil water (or available water capacity) is the amount of water held in soil between field capacity (upper limit) and permanent wilting point (lower limit) that plants can extract for growth and transpiration. Water above field capacity (gravitational water) drains away, while water below PWP is unavailable .
The “readily available moisture” (RAM) is typically what percentage of total available moisture? a) 100% b) 75-80% c) 50-60% d) 25-30%
Answer: b) 75-80%
*Explanation: Readily Available Moisture (RAM) is the portion of total available moisture that plants can extract without experiencing moisture stress. It is typically 75-80% of total available moisture. Irrigation should be scheduled before soil moisture depletes below RAM to avoid yield loss. This concept is critical for irrigation scheduling .*
In irrigation scheduling, the “management allowed deficit” (MAD) for most crops is usually: a) 10-20% of available moisture b) 30-50% of available moisture c) 60-70% of available moisture d) 80-90% of available moisture
Answer: b) 30-50% of available moisture
*Explanation: Management Allowed Deficit (MAD) is the fraction of available soil moisture that can be safely depleted before irrigation is needed without causing crop stress. For most crops, MAD is 30-50% of available moisture. Sensitive crops (vegetables) require lower MAD (30-40%), while drought-tolerant crops can have higher MAD (50-60%) .*
The “peak rate of moisture use” by a crop occurs during: a) Germination stage b) Vegetative growth stage c) Reproductive stage (flowering and grain filling) d) Maturity stage
Answer: c) Reproductive stage (flowering and grain filling)
*Explanation: The peak rate of moisture use (maximum evapotranspiration) occurs during the reproductive stage (flowering and grain filling) for most crops. This is the most critical period for irrigation, as moisture stress during this stage directly affects yield by reducing pollination, grain set, and grain development. For wheat, the CRI stage (20-25 DAS) is also critical .*
The “water application efficiency” (Ea) is defined as: a) (Water stored in root zone / Water delivered to field) × 100 b) (Water delivered to field / Water diverted from source) × 100 c) (Water beneficially used / Water delivered to field) × 100 d) (Water evapotranspired / Water applied) × 100
Answer: a) (Water stored in root zone / Water delivered to field) × 100
*Explanation: Water application efficiency (Ea) measures how effectively water is applied to the field. It is the ratio of water stored in the root zone during irrigation to the total water delivered to the field, expressed as percentage. Losses include runoff and deep percolation. For surface irrigation, Ea is 50-70%; for sprinkler, 70-80%; for drip, 90-95% .*
The “water conveyance efficiency” (Ec) is calculated as: a) (Water delivered to field / Water diverted from source) × 100 b) (Water stored in root zone / Water delivered) × 100 c) (Water used by crop / Water applied) × 100 d) (Water evapotranspired / Water applied) × 100
Answer: a) (Water delivered to the field / Water diverted from the source) × 100
*Explanation: Conveyance efficiency measures the efficiency of water transport from the source (reservoir, canal head) to the field. Losses occur through seepage, evaporation, and percolation in canals. Lined canals have higher Ec (90-95%) than unlined canals (60-70%). This is a key parameter in irrigation system design .*
The “overall project efficiency” for an irrigation project is the product of: a) Conveyance efficiency × Application efficiency b) Conveyance efficiency × Distribution efficiency c) Application efficiency × Storage efficiency d) Conveyance efficiency × Application efficiency × Distribution efficiency
Answer: a) Conveyance efficiency × Application efficiency
*Explanation: Overall project efficiency (Ep) is the product of conveyance efficiency (water transport from source to field) and application efficiency (water storage in root zone). It represents the fraction of water diverted from the source that is actually stored in the crop root zone. For typical surface irrigation projects, Ep ranges from 40-50% .*
In the problem: “An area of 20 ha needs to be irrigated. Available moisture holding capacity is 16 cm/m of soil, root zone depth 1.0 m, irrigation done when 50% of available moisture is depleted, peak moisture use 4.0 mm/day, application efficiency 70%. The irrigation period is:” The correct answer is: a) 10 days b) 20 days c) 25 days d) 30 days
Answer: b) 20 days
*Explanation: Step 1: Available moisture = 16 cm/m × 1.0 m = 16 cm = 160 mm Step 2: Depletion allowed = 50% of 160 mm = 80 mm Step 3: Net irrigation depth = 80 mm Step 4: Gross irrigation depth = Net depth / Efficiency = 80 / 0.70 = 114.3 mm Step 5: Daily water use = 4.0 mm/day Step 6: Irrigation interval = Net depth / Daily use = 80 mm / 4 mm/day = 20 days This calculation matches standard irrigation scheduling problems .*
The “CropWat” model developed by FAO is used for: a) Crop yield prediction only b) Estimating crop water requirements and irrigation scheduling c) Fertilizer recommendation d) Pest forecasting
Answer: b) Estimating crop water requirements and irrigation scheduling
Explanation: CropWat is a decision support tool developed by FAO (Food and Agriculture Organization) for calculating crop water requirements, irrigation requirements, and developing irrigation schedules based on soil, climate, and crop data. It uses the FAO Penman-Monteith method for reference evapotranspiration (ETo) calculation .
The FAO Penman-Monteith method is considered the standard for estimating: a) Crop yield b) Reference evapotranspiration (ETo) c) Soil moisture d) Groundwater recharge
Answer: b) Reference evapotranspiration (ETo)
Explanation: The FAO Penman-Monteith method is the sole standard method for computing reference evapotranspiration (ETo) from meteorological data. It represents the evapotranspiration from a hypothetical grass reference surface with specific characteristics. Actual crop evapotranspiration (ETc) is calculated as ETc = ETo × Kc (crop coefficient) .
The “crop coefficient (Kc)” varies primarily with: a) Soil type b) Crop growth stage c) Fertilizer application d) Irrigation method
Answer: b) Crop growth stage
*Explanation: The crop coefficient (Kc) varies with crop growth stage. Typical Kc values: initial stage (0.3-0.5), mid-season (1.0-1.2), and late season (0.7-0.9). Kc integrates the difference between crop evapotranspiration (ETc) and reference evapotranspiration (ETo) based on crop characteristics, canopy cover, and ground surface conditions .*
The “soil moisture depletion method” for irrigation scheduling involves irrigating when: a) A fixed calendar date arrives b) Soil moisture reaches a predetermined depletion level c) Plants show wilting symptoms d) Rainfall occurs
Answer: b) Soil moisture reaches a predetermined depletion level
Explanation: The soil moisture depletion method (or soil water potential method) schedules irrigation based on actual soil moisture measurements. Irrigation is applied when soil moisture depletes to a predetermined threshold (e.g., 50% of available moisture). This method uses tools like tensiometers, gypsum blocks, or neutron probes for measurement .
A tensiometer is used to measure: a) Soil pH b) Soil moisture tension (matrix potential) c) Electrical conductivity d) Nutrient content
Answer: b) Soil moisture tension (matrix potential)
*Explanation: A tensiometer measures soil moisture tension (matrix potential) in centibars (cb) or kilopascals (kPa). It consists of a porous ceramic cup filled with water, connected to a vacuum gauge. As soil dries, water is pulled out through the cup, creating tension. Tensiometers are effective in the range of 0-80 cb (field capacity to just below readily available moisture) .*
The “neutron probe” (Neutron Moisture Meter) works on the principle of: a) Electrical resistance b) Thermal conductivity c) Slowing down of fast neutrons by hydrogen atoms in water d) Dielectric constant
Answer: c) Slowing down of fast neutrons by hydrogen atoms in water
*Explanation: The neutron probe contains a source of fast neutrons (Americium-241/Beryllium) and a detector. Fast neutrons are slowed down (thermalized) by collision with hydrogen atoms in soil water. The count of thermal neutrons is proportional to soil moisture content. It requires site-specific calibration and safety precautions due to radioactive source .*
The “Time Domain Reflectometry” (TDR) method measures soil moisture based on: a) Electrical conductivity b) Dielectric constant of soil c) Neutron thermalization d) Gamma ray attenuation
Answer: b) Dielectric constant of soil
*Explanation: TDR measures soil moisture by determining the dielectric constant of soil, which is strongly dependent on water content (dielectric constant of water ~80, air ~1, soil minerals ~3-5). TDR sends an electromagnetic pulse along waveguides (rods) inserted in soil and measures the travel time, which is related to soil moisture. It provides rapid, accurate, non-destructive measurements .*
The “check basin” method of irrigation is most suitable for: a) Sloping lands b) Sandy soils with high infiltration c) Level lands with close-growing crops (wheat, rice) d) Orchards on slopes
Answer: c) Level lands with close-growing crops (wheat, rice)
Explanation: Check basin irrigation involves dividing the field into level plots (basins) surrounded by bunds. Water is ponded within each basin. This method is suitable for level lands and close-growing crops like wheat, rice, and jowar. It gives good water distribution control but requires land leveling and has high labor requirement for bund maintenance .
The “border strip” method of irrigation is characterized by: a) Water applied to individual plants through emitters b) Field divided into strips separated by low borders, water flows as sheet down the strip c) Water applied through perforated pipes d) Land divided into small basins
Answer: b) Field divided into strips separated by low borders, water flows as sheet down the strip
*Explanation: Border strip irrigation involves dividing the field into strips (10-20 m wide, 100-400 m long) separated by low borders. Water is applied at the upper end and flows as a thin sheet down the strip. It is suitable for close-growing crops (alfalfa, clover, wheat) on moderate slopes (0.5-2%). It requires less labor than check basins but needs proper slope and uniform soil .*
The “furrow irrigation” method is most suitable for: a) Rice b) Wheat c) Row crops (cotton, maize, sugarcane, vegetables) d) Pasture crops
Answer: c) Row crops (cotton, maize, sugarcane, vegetables)
Explanation: Furrow irrigation involves creating small channels (furrows) between crop rows. Water flows through furrows and infiltrates laterally to the ridges where plants grow. It is ideal for row crops like cotton, maize, sugarcane, potatoes, and vegetables. Advantages include: less evaporation loss (only part of soil surface wetted), ability to irrigate without wetting foliage (reduces disease), and suitability for moderate slopes .
