- The “Herbicide Resistance Action Committee” (HRAC) classifies herbicides based on:
a) Chemical structure only
b) Mode of action
c) Price
d) Formulation type
- Answer: b) Mode of action
- Explanation: HRAC classifies herbicides by their mode of action (MOA) – how they kill plants (e.g., ALS inhibitors, ACCase inhibitors, Photosystem II inhibitors). This classification helps in rotating herbicides with different MOA to prevent and manage herbicide resistance in weeds.
- “Bispyribac-sodium” is a herbicide used for:
a) Broad-spectrum weed control in wheat
b) Post-emergence grass and broadleaf weed control in rice
c) Pre-emergence weed control in maize
d) Perennial weed control in sugarcane
- Answer: b) Post-emergence grass and broadleaf weed control in rice
- *Explanation: Bispyribac-sodium is an ALS inhibitor herbicide widely used for post-emergence control of grasses (Echinochloa), sedges, and broadleaf weeds in direct-seeded and transplanted rice. It’s effective at low doses (20-25 g/ha) and has become popular in rice weed management.*
- The “half-life” (t½) of a herbicide in soil refers to:
a) Time for 50% of herbicide to be dissipated
b) Time for complete dissipation
c) Time for 25% dissipation
d) Time for 75% dissipation
- Answer: a) Time for 50% of herbicide to be dissipated
- *Explanation: Half-life (t½) is the time required for 50% of the initial herbicide concentration to dissipate from soil through degradation (microbial, chemical), volatilization, leaching, or plant uptake. It indicates persistence – herbicides with t½ > 60 days are persistent (atrazine), while t½ < 30 days are non-persistent (glyphosate).*
- “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 in plants. This stops cell division and plant growth. They’re highly active at low doses (grams/ha).
5. “Pendimethalin” belongs to which herbicide group?
a) Phenoxy
b) Dinitroaniline
c) Triazine
d) Urea
- Answer: b) Dinitroaniline
- Explanation: Pendimethalin is a dinitroaniline herbicide that inhibits microtubule formation during cell division, preventing root and shoot development in germinating weeds. It’s a pre-emergence herbicide used in many crops including rice, wheat, maize, soybean, and vegetables.
- The “formulation code ‘EC'” in herbicides stands for:
a) Emulsifiable Concentrate
b) Extra Concentrated
c) Effective Chemical
d) Environmental Control
- Answer: a) Emulsifiable Concentrate
- Explanation: EC (Emulsifiable Concentrate) is a liquid formulation containing active ingredient dissolved in organic solvent with emulsifiers. When mixed with water, it forms a milky emulsion. Other common formulations: WP (Wettable Powder), SC (Suspension Concentrate), WDG (Water Dispersible Granules).
- “Adjuvants” in herbicide application are added to:
a) Increase toxicity to crop
b) Enhance herbicide effectiveness (spreading, sticking, penetration)
c) Dilute the herbicide
d) Change herbicide color
- Answer: b) Enhance herbicide effectiveness (spreading, sticking, penetration)
- Explanation: Adjuvants are substances added to herbicide spray mixtures to enhance their effectiveness. Types include surfactants (improve spreading), stickers (increase rainfastness), penetrants (enhance leaf uptake), and drift retardants. They don’t have herbicidal activity themselves.
- “Temperature inversion” in meteorology is dangerous for herbicide application because:
a) Herbicide evaporates quickly
b) Spray droplets may drift long distances without dispersing
c) Herbicide becomes inactive
d) Plants stop absorbing herbicide
- Answer: b) Spray droplets may drift long distances without dispersing
- Explanation: During temperature inversion (cool air near ground, warmer above), air is stable with minimal vertical mixing. Spray droplets remain suspended in concentrated layers and can drift long distances (miles) to damage sensitive crops. Application should be avoided during inversions (early morning, evening).
- “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
- 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. Example: Atrazine + alachlor in maize shows synergism. This allows lower doses, broader spectrum control, and resistance management.
- The “critical period” for crop-weed competition in soybean is:
a) First 15 days after sowing
b) 20-45 days after sowing
c) 60-75 days after sowing
d) Throughout the season
- Answer: b) 20-45 days after sowing
- *Explanation: In soybean, the critical period of weed competition is 20-45 days after sowing (first 4-6 weeks). Weeds emerging during this period cause maximum yield loss (30-60%). After canopy closure (45-50 days), soybean suppresses later-emerging weeds through shading.*
- “Phytotoxicity” in crops due to herbicides can be diagnosed by:
a) Increased growth
b) Chlorosis, necrosis, epinasty, stunting, malformation
c) Dark green leaves
d) Early flowering
- Answer: b) Chlorosis, necrosis, epinasty, stunting, malformation
- *Explanation: Herbicide phytotoxicity symptoms vary by herbicide group: auxin-type (2,4-D) cause epinasty, leaf curling; PSII inhibitors (atrazine) cause interveinal chlorosis; ALS inhibitors cause stunting and purple discoloration; cell membrane disruptors (paraquat) cause rapid necrosis and burning.*
- “False seedbed” technique is also known as:
a) Stale seedbed
b) Zero tillage
c) Mulch tillage
d) Ridge tillage
- Answer: a) Stale seedbed
- Explanation: False seedbed and stale seedbed are same technique – preparing seedbed, allowing weed seeds to germinate, destroying them (by tillage or non-selective herbicide), and then sowing crop. This reduces the initial weed seed bank and delays weed emergence relative to crop.
- The “critical limit” for boron in soil for most crops is:
a) 0.1 ppm
b) 0.5 ppm
c) 1.0 ppm
d) 2.0 ppm
- Answer: b) 0.5 ppm
- *Explanation: The critical limit for hot water-soluble boron in soil is 0.5 ppm. Below this, boron deficiency occurs in sensitive crops (cauliflower, tomato, apple, sunflower). Boron is essential for pollen germination, fruit set, and cell wall formation. Deficiency causes “heart rot” in sugarbeet and “brown heart” in turnips.*
- “Molybdenum” deficiency in cauliflower causes:
a) Curd formation failure
b) Whiptail disease (narrow, distorted leaves)
c) Purple discoloration
d) Interveinal chlorosis
- Answer: b) Whiptail disease (narrow, distorted leaves)
- Explanation: Molybdenum deficiency in cauliflower and other brassicas causes “whiptail” – leaves become narrow, distorted, with ruffled margins and reduced lamina. Mo is essential for nitrate reductase enzyme; deficiency leads to nitrate accumulation and poor protein synthesis. Liming acid soils increases Mo availability.
- “Chlorine” as an essential plant nutrient is required for:
a) Photosynthesis
b) Osmotic regulation and disease resistance
c) Protein synthesis
d) Cell wall formation
- Answer: b) Osmotic regulation and disease resistance
- Explanation: Chlorine (Cl) is a micronutrient essential for osmosis, stomatal regulation, and disease resistance. It’s involved in water splitting during photosynthesis (Photosystem II). Deficiency is rare (atmospheric deposition, irrigation water supplies Cl). Excess Cl causes toxicity (leaf burn) in sensitive crops (tobacco, potato).
- “Nickel” was established as an essential plant nutrient in:
a) 1950s
b) 1987
c) 2000
d) 2010
- Answer: b) 1987
- *Explanation: Nickel (Ni) was established as an essential micronutrient in 1987. It’s a component of the enzyme urease, which converts urea to ammonia in plants. Ni deficiency causes urea toxicity (leaf tip necrosis) in crops fertilized with urea. Required in very low amounts (0.05-5 ppm dry weight).*
- “Cobalt” is essential for which group of plants?
a) All plants
b) Legumes (for nitrogen fixation by Rhizobium)
c) Cereals only
d) Oilseeds only
- Answer: b) Legumes (for nitrogen fixation by Rhizobium)
- *Explanation: Cobalt is not essential for higher plants but is essential for nitrogen-fixing bacteria (Rhizobium) in legume nodules. It’s a component of vitamin B12, required for nitrogenase enzyme activity. Co deficiency in legumes reduces nitrogen fixation, causing N deficiency symptoms.*
- . “Vanadium” is essential for:
a) All crops
b) Some green algae and nitrogen-fixing bacteria
c) Cereals only
d) Oilseeds only
- Answer: b) Some green algae and nitrogen-fixing bacteria
- Explanation: Vanadium is essential for some green algae and alternative nitrogenase systems in certain nitrogen-fixing bacteria (Azotobacter). Its essentiality for higher plants hasn’t been conclusively established, though it may have beneficial effects at low concentrations.
- “Sodium” is considered a beneficial element for:
a) All crops
b) Halophytes and C4 plants (especially sugarcane, sugarbeet)
c) Legumes only
d) Cereals only
- Answer: b) Halophytes and C4 plants (especially sugarcane, sugarbeet)
- Explanation: Sodium is not essential for most plants but is beneficial for halophytes and some C4 plants (sugarcane, sugarbeet, saltbush). It can partially replace potassium in osmotic functions, stimulate growth, and improve water relations. Sugarbeet shows yield response to Na even when K is adequate.
- “Silicon” accumulation in rice helps in:
a) Increasing protein content
b) Lodging resistance and pest/disease tolerance
c) Early flowering
d) Root nodulation
- Answer: b) Lodging resistance and pest/disease tolerance
- Explanation: Silicon is a beneficial element for rice, sugarcane, and horsetails. It deposits in cell walls as silica, strengthening stems (lodging resistance), making leaves erect (better light interception), and providing mechanical barriers against fungal pathogens (blast, sheath blight) and insect pests (stem borer).
- “Aluminum toxicity” in acid soils primarily affects:
a) Leaf development
b) Root growth (inhibits cell division and elongation)
c) Flowering
d) Seed germination
- Answer: b) Root growth (inhibits cell division and elongation)
- *Explanation: Aluminum toxicity (pH <5.5) primarily damages root systems – inhibits cell division in root tips, reduces root elongation, makes roots stubby and brittle. This reduces water and nutrient uptake, causing P deficiency, Ca deficiency, and drought susceptibility. Liming to pH >5.5 precipitates Al as insoluble hydroxides.*
- “Manganese toxicity” symptoms in plants include:
a) Interveinal chlorosis on young leaves
b) Brown spots on older leaves, crinkling, and chlorosis
c) Purple discoloration
d) Wilting
- Answer: b) Brown spots on older leaves, crinkling, and chlorosis
- *Explanation: Mn toxicity (common in acid soils, pH <5.5) causes brown spots on older leaves (oxidized MnO₂ deposits), leaf crinkling, marginal chlorosis, and sometimes “speckled yellows.” It interferes with Fe metabolism, causing secondary Fe deficiency. Liming and avoiding over-acidification prevent toxicity.*
- “Iron toxicity” in lowland rice occurs due to:
a) High soil pH
b) Reduction of Fe³⁺ to Fe²⁺ in flooded conditions
c) Low organic matter
d) Sandy soils
- Answer: b) Reduction of Fe³⁺ to Fe²⁺ in flooded conditions
- Explanation: In flooded rice soils, anaerobic conditions reduce insoluble Fe³⁺ to soluble Fe²⁺. Excess Fe²⁺ uptake causes “bronzing” – small brown spots on lower leaves starting from tips, reducing yield. Tolerance varies by variety. Management includes liming, P application, and growing tolerant varieties.
- “Zinc-phosphate interaction” in soils refers to:
a) Synergistic effect on crop yield
b) Induced Zn deficiency by high P application
c) Improved P availability by Zn
d) No interaction
- Answer: b) Induced Zn deficiency by high P application
- *Explanation: High phosphorus application can induce or exacerbate zinc deficiency (P-induced Zn deficiency). Mechanisms include: (1) dilution effect (P stimulates growth, diluting Zn in tissues), (2) P-Zn antagonism in uptake, (3) reduced mycorrhizal colonization. Balanced P and Zn application is essential.*
- The “Law of the Minimum” (Liebig’s Law) states that:
a) All nutrients are equally limiting
b) Crop yield is limited by the nutrient in shortest supply relative to demand
c) Maximum nutrient gives maximum yield
d) Nutrients never limit yield
- Answer: b) Crop yield is limited by the nutrient in shortest supply relative to demand
- *Explanation: Justus von Liebig’s “Law of the Minimum” (1840) states that crop yield is determined by the nutrient in shortest supply (the limiting factor), even if all other nutrients are adequate. This is often illustrated by a barrel with staves of different lengths – water level (yield) is limited by the shortest stave.*
- The “critical stage” for irrigation in wheat is Crown Root Initiation (CRI). This stage occurs at how many days after sowing (DAS)?
a) 10-15 DAS
b) 20-25 DAS
c) 35-40 DAS
d) 50-55 DAS
- Answer: b) 20-25 DAS
- *Explanation: The Crown Root Initiation (CRI) stage in wheat occurs 20-25 days after sowing. This is the most critical stage for irrigation as moisture stress during CRI severely affects tillering and yield potential. This question pattern appears frequently in ICAR JRF, ASRB NET, and State AO exams .*
- Which instrument is used to measure Leaf Area Index (LAI)?
a) Lux meter
b) Ceptometer
c) Spectrophotometer
d) Pyranometer
- Answer: b) Ceptometer
- Explanation: A ceptometer is specifically designed to measure Leaf Area Index by quantifying light interception through the canopy. This question appeared in IBPS AFO memory-based papers, testing knowledge of agricultural instruments .
- Which state is the largest producer of rubber in India?
a) Karnataka
b) Kerala
c) Tamil Nadu
d) Andhra Pradesh
- Answer: b) Kerala
- Explanation: Kerala is the largest producer of natural rubber in India, accounting for over 70% of total production. This question appeared in BPSC (Pre) 1994 and is frequently asked in state PSC exams .
- ICAR-Central Institute of Agricultural Engineering (CIAE) is located at:
a) Bhopal
b) Kanpur
c) Pune
d) Hyderabad
- Answer: a) Bhopal
- Explanation: ICAR-Central Institute of Agricultural Engineering (CIAE) is located in Bhopal, Madhya Pradesh. This type of question testing knowledge of ICAR institute locations appears regularly in ICAR JRF and AFO exams .
- “Marigold” is used as a trap crop for which pest?
a) Aphids
b) Whiteflies
c) Nematodes
d) Jassids
- Answer: c) Nematodes
- Explanation: Marigold (Tagetes spp.) is used as a trap crop for nematodes due to its root exudates that attract and trap root-knot nematodes. This question appeared in IBPS AFO memory-based papers and tests integrated pest management knowledge .
- PSB (Phosphate Solubilizing Bacteria) is used for solubilizing which nutrient?
a) Nitrogen
b) Potassium
c) Phosphorus
d) Sulphur
- Answer: c) Phosphorus
- Explanation: Phosphate Solubilizing Bacteria (PSB) like Pseudomonas straita and Bacillus megaterium convert insoluble soil phosphorus into plant-available forms. This question is frequently asked in ASRB NET, ICAR JRF, and State AO exams .
- The government sets MSP at what multiple of the cost of production?
a) 1.2 times
b) 1.5 times
c) 2.0 times
d) 2.5 times
- Answer: b) 1.5 times
- *Explanation: The government sets Minimum Support Price (MSP) at 1.5 times the cost of production (A2+FL cost). This is a standard question in NABARD Grade A, IBPS AFO, and banking sector agriculture exams .*
- “Pusa Jai Kisan” is a variety of which crop?
a) Rice
b) Wheat
c) Mustard
d) Maize
- Answer: b) Wheat
- Explanation: Pusa Jai Kisan is a wheat variety developed by IARI. This question appeared in IBPS AFO memory-based papers and is typical of State AO exams like RPSC AAO .
- Which state has the highest productivity of rice?
a) Punjab
b) West Bengal
c) Uttar Pradesh
d) Andhra Pradesh
- Answer: a) Punjab
- *Explanation: Punjab has the highest rice productivity in India due to better irrigation facilities, high-yielding varieties, and mechanization. This question appeared in PSC (Pre) 2019 and is common in state PSC exams .*
- “Muga” silkworm feeds on which plant?
a) Morus alba
b) Terminalia arjuna
c) Machilus bombycina
d) Ricinus communis
- Answer: c) Machilus bombycina
- Explanation: Muga silkworm (Antheraea assamensis) primarily feeds on Machilus bombycina (Som) and Litsea monopetala (Soalu). This question appeared in IBPS AFO exams and tests knowledge of sericulture .
- “Gibberellin” was first isolated from:
a) Bacteria
b) Fungus
c) Algae
d) Virus
- Answer: b) Fungus
- Explanation: Gibberellin was first isolated from the fungus Gibberella fujikuroi (causes “bakanae” disease in rice) by Japanese scientists. This is a frequently asked question in plant physiology sections of various agriculture exams .
- What is the chief cause of low crop yields in India?
a) Small size of holdings
b) Traditional methods of farming
c) Low level of farm mechanization
d) All of the above
- Answer: d) All of the above
- Explanation: Low crop yields in India result from multiple factors: small and fragmented land holdings, traditional farming methods, inadequate mechanization, poor irrigation facilities, and illiteracy. This question appeared in various state PSC exams .
- “Vanraja” chicken variety was developed by which institute?
a) CARI, Izzatnagar
b) DPR, Hyderabad
c) IVRI, Izatnagar
d) NDRI, Karnal
- Answer: a) CARI, Izzatnagar
- Explanation: Vanraja chicken variety was developed by Central Avian Research Institute (CARI), Izzatnagar. This crossbred variety is suitable for backyard poultry farming. This question appeared in IBPS AFO exams .
- The “Law of the Minimum” was proposed by:
a) Charles Darwin
b) Justus von Liebig
c) Gregor Mendel
d) Norman Borlaug
- Answer: b) Justus von Liebig
- Explanation: Justus von Liebig proposed the “Law of the Minimum” in 1840, stating that crop yield is limited by the nutrient in shortest supply relative to demand. This fundamental principle of plant nutrition is frequently tested in ASRB NET and ICAR JRF exams.
- Which organization is the convenor of Sub-Committees of the District Consultative Committee for credit regulation?
a) Lead District Manager
b) NABARD
c) RBI
d) District Collector
- Answer: a) Lead District Manager
- Explanation: The Lead District Manager (LDM) is appointed as the convenor of Sub-Committees of the District Consultative Committee for credit regulation. This question appeared in IBPS AFO exams and tests knowledge of agricultural credit structure .
- “Arka Puneet” is a variety of which fruit crop?
a) Apple
b) Mango
c) Banana
d) Citrus
- Answer: b) Mango
- Explanation: Arka Puneet is a mango variety developed by IIHR, Bangalore, through crossing Alphonso × Banganapalli. It is resistant to spongy tissue and produces oval-shaped fruits. This appeared in IBPS AFO memory-based questions .
- The “half-life” (t½) of a herbicide refers to:
a) Time for 50% dissipation
b) Time for complete dissipation
c) Time for 25% dissipation
d) Time for 75% dissipation
- Answer: a) Time for 50% dissipation
- *Explanation: Half-life (t½) is the time required for 50% of the initial herbicide concentration to dissipate from soil through degradation, volatilization, leaching, or plant uptake. This concept is tested in weed management sections of various exams.*
- Which organism proliferates in environments with high organic substrate conditions?
a) Autotrophs
b) Heterotrophs
c) Autochthonous
d) Biotrophs
- Answer: c) Autochthonous
- Explanation: Autochthonous microorganisms are native to the soil and proliferate in environments with high organic substrate conditions. This question appeared in IBPS AFO exams and tests soil microbiology knowledge .
- The “critical limit” for available zinc (DTPA-extractable) in soil for most crops is:
a) 0.2 ppm
b) 0.6 ppm
c) 1.2 ppm
d) 2.5 ppm
- Answer: b) 0.6 ppm
- *Explanation: The critical limit for DTPA-extractable zinc in soil is 0.6 ppm. Soils with Zn below this are considered deficient. Zinc deficiency affects about 50% of Indian soils and is frequently tested in soil science sections.*
- The “oestrous cycle” duration in ewe (sheep) is:
a) 16 days (14-19 days)
b) 10 days (6-14 days)
c) 21 days (20-25 days)
d) 30 days (28-32 days)
- Answer: a) 16 days (14-19 days)
- *Explanation: The oestrous cycle in ewe (sheep) is approximately 16 days, ranging from 14-19 days. This question appeared in IBPS AFO exams and tests animal husbandry knowledge required for Agriculture Field Officers .*
- Which of the following is a non-protein nitrogen component in fish?
a) Collagen
b) Myosin
c) TMAO (Trimethylamine oxide)
d) Trypsin
- Answer: c) TMAO (Trimethylamine oxide)
- Explanation: TMAO (Trimethylamine oxide) is a non-protein nitrogen component in fish that contributes to its characteristic odor and flavor. This question appeared in IBPS AFO exams and tests fisheries science knowledge .
- “Lordosis” disease in fish is caused by deficiency of which vitamin?
a) Vitamin A
b) Vitamin C
c) Vitamin D
d) Vitamin E
- Answer: b) Vitamin C
- Explanation: Lordosis (spinal deformity) in fish is caused by Vitamin C (ascorbic acid) deficiency. Vitamin C is essential for collagen synthesis and proper bone formation in fish. This appeared in IBPS AFO memory-based questions .
- What is the germination percentage required for hybrid seed production of tomato?
a) 70%
b) 75%
c) 80%
d) 85%
- Answer: c) 80%
- Explanation: The minimum germination percentage required for hybrid tomato seed production is 80%. Seed quality standards are frequently tested in seed technology sections of state agriculture exams .
- What is the electrical conductivity (EC) range of soil (dS/m) considered good for satisfactory crop production under proper drainage?
a) 0.1-0.25
b) 0.5-2.0
c) 3.0-4.0
d) 4.0-6.0
- Answer: b) 0.5-2.0 dS/m
- *Explanation: Soils with electrical conductivity between 0.5-2.0 dS/m are considered good for satisfactory crop production under proper drainage practices. EC > 4 dS/m indicates saline soils. This question appeared in IBPS AFO exams .*
- The “drum head culture technique” is used to determine water requirement of which crop?
a) Wheat
b) Rice
c) Potato
d) Sugarcane
- Answer: b) Rice
- Explanation: Drum head culture technique (or drum culture technique) is used to determine water requirement of rice by growing plants in drums/containers and measuring water consumption. This question appeared in IBPS AFO memory-based papers
