1. The botanical name of cultivated rice, most widely grown worldwide, is:
A. Triticum aestivum
B. Oryza sativa
C. Zea mays
D. Sorghum bicolor
Answer: B
Rationale: The most widely cultivated species of rice is Oryza sativa (Asian rice), while Zea mays is maize and Triticum aestivum is wheat.
2. The recommended seed rate for transplanted paddy in typical irrigated lowland systems is approximately:
A. 10 kg/ha
B. 20 kg/ha
C. 50 kg/ha
D. 100 kg/ha
Answer: C
Rationale: To raise sufficient nursery seedlings (~350 m² per hectare), around 50 kg/ha of good-quality seed is recommended for transplanted rice production (Cultivar).
3. In the nursery bed, the sowing depth/watering depth after emergence should be about:
A. 1–3 cm
B. 5–6 cm
C. 8–10 cm
D. Field flooded ≥10 cm
Answer: A
Rationale: Nursery beds post-germination should be kept moist under shallow water (≈1–3 cm) to support root growth without suffocating seedlings (Infonet Biovision).
4. In conventional transplanted rice, seedlings should be 21–30 days old (4–5 leaves) when transplanted to:
A. Maximize tillering.
B. Reduce seedling shock.
C. Under SRI only.
D. Conserve water.
Answer: A
Rationale: Thirty-day-old seedlings with 4–5 leaves are standard in conventional systems to ensure sufficient tillering and stand establishment (sri.ciifad.cornell.edu, Infonet Biovision).
5. Under the System of Rice Intensification (SRI), the ideal age of seedlings at transplanting is:
A. 5–7 days
B. 8–12 days
C. 15–20 days
D. 21–30 days
Answer: B
Rationale: SRI emphasises transplanting very young seedlings (about 8–12 days old, 2-leaf stage) to promote stronger root systems and tillering (rice-garud.icar-web.com).
6. The recommended plant spacing in SRI (square grid) is generally about:
A. 10 × 10 cm
B. 20 × 15 cm
C. 25 × 25 cm or wider
D. Broadcasting
Answer: C
Rationale: SRI principles include wider square spacing (often 25 × 25 cm or more) to reduce competition and enhance aeration (UC IPM).
7. A typical transplanting spacing for high-yielding hybrid varieties (HYV) is:
A. 10 × 10 cm
B. 15 × 10 cm
C. 20 × 15 cm
D. 30 × 30 cm
Answer: C
Rationale: For HYV rice in India, a commonly used spacing is 20 × 15 cm to balance density and tillering (icar-nrri.in).
8. Transplanting depth into the main field should be shallow, around:
A. 0.5–1 cm
B. 2–3 cm
C. 5–6 cm
D. 8–10 cm
Answer: B
Rationale: Shallow transplantation (≈2–3 cm) ensures faster root establishment and better tiller development; deeper planting can reduce tillering (Infonet Biovision).
9. The ideal soil pH range for maximum nutrient availability and rice growth is:
A. 4.0–5.0
B. 4.0–6.0
C. 5.0–6.5
D. 7.0–8.0
Answer: C
Rationale: Rice thrives in mildly acidic soils, with optimal pH range of approximately 5.0–6.5 for nutrient uptake (Wikipedia).
10. For Kharif/monsoon-irrigated lowland rice, the standard N-P₂O₅-K₂O blanket recommendation in India is:
A. 40-20-20 kg/ha
B. 60-30-30 kg/ha
C. 80-40-40 kg/ha
D. 100‑60‑60 kg/ha
Answer: B
Rationale: The commonly recommended fertility dosage for irrigated lowland Kharif rice is 60‑30‑30 kg N‑P₂O₅‑K₂O per hectare (plantwiseplusknowledgebank.org).
11. For hybrid rice, the suggested NPK level is:
A. 40‑20‑20
B. 60‑30‑30
C. 80‑40‑40
D. 100‑60‑60 kg/ha
Answer: D
Rationale: Hybrid rice varieties typically respond to the higher fertilizer rates of 100‑60‑60 kg/ha to achieve optimal yield (icar-nrri.in).
12. Typical nitrogen split application schedule is:
A. 100% basal
B. 50% basal, 50% panicle initiation
C. 25% basal, 50% tillering, 25% panicle initiation
D. 33% each at basal, tillering, and heading
Answer: C
Rationale: A split N schedule (¼ basal, ½ at tillering, ¼ at panicle initiation) aligns with grower practice in many regions (Cultivar).
13. Applying 25 kg ZnSO₄/ha at puddling is recommended to:
A. Improve root pruning.
B. Prevent lodging.
C. Correct zinc deficiency.
D. Suppress weeds.
Answer: C
Rationale: Zinc application (≈25 kg/ha as zinc sulphate) is standard in puddling to correct Zn deficiency and ensure normal growth (UC IPM).
14. Incorporation of Azolla (a water fern) in rice fields typically contributes about:
A. 10 kg N/ha
B. 20‑25 kg N/ha
C. 40‑50 kg N/ha
D. 100 kg N/ha
Answer: C
Rationale: Azolla biofertilization can fix and return around 40–50 kg N/ha during the growth season (icar-nrri.in).
15. The pre-emergence herbicide Butachlor is commonly applied at a dose of:
A. 0.5 kg/ha
B. 1.25–2 kg/ha
C. 5 kg/ha
D. 10 kg/ha
Answer: B
Rationale: Butachlor is typically used at 1.25–2 kg of active ingredient per hectare as pre-emergence herbicide in rice (Wikipedia).
16. When should the herbicide Butachlor be applied in transplanted rice?
A. Before puddling
B. Immediately after puddling, before transplanting
C. 2–3 days after transplanting
D. At 30 days after transplanting
Answer: C
Rationale: Butachlor is broadcast into standing water 2–3 days after transplanting, when weeds are small and water depth ≈4‑5 cm (apnikheti.com).
17. In conventional flooded-rice systems, alternate wetting and drying (AWD) is used in SRI to:
A. Increase methane emissions
B. Stimulate tillering and save water
C. Keep fields constantly submerged
D. Promote weed growth
Answer: B
Rationale: AWD—an SRI strategy—saves 30‑50% of irrigation water and accelerates root and tiller development (adama.com).
18. SRI farmers often record water savings compared to conventional methods by about:
A. 5–10%
B. 15–20%
C. 25–50%
D. 60–75%
Answer: C
Rationale: SRI has delivered water savings in the range of 25–50%, while increasing yields by 20–50% (sri.cals.cornell.edu, link.springer.com).
19. In SRI systems, seed use is reduced by approximately:
A. 10%
B. 30%
C. 50%
D. 80–90%
Answer: D
Rationale: SRI nursery management requires only ~10% of usual seed rates, reducing seed use by 80–90% (sri.cals.cornell.edu).
20. Which of the following would increase risk of rice blast disease?
A. Moderate plant density
B. Low-nitrogen application
C. Overhead sprinkler irrigation
D. High nitrogen application
Answer: D
Rationale: High nitrogen promotes succulent growth and canopy humidity, increasing rice blast risk (plantwiseplusknowledgebank.org).
21. The characteristic shape of rice blast lesions on leaves is:
A. Circular with concentric rings
B. Oval with white center and brown border
C. Diamond-shaped with grey center and dark margin
D. Linear stripes along leaf veins
Answer: C
Rationale: Blast lesions are typically diamond-shaped, grey in the center with a reddish-brown border (UC IPM).
22. One effective fungicide for rice blast acts by inhibiting melanin biosynthesis:
A. Captan
B. Carbendazim
C. Tricyclazole
D. Mancozeb
Answer: C
Rationale: Tricyclazole targets melanin biosynthesis (melanin-dehydratase pathway), disrupting appressorium formation in Magnaporthe oryzae (Cultivar).
23. Since tricyclazole is restricted, current effective alternatives for blast include combinations of:
A. Copper sulfate + urea
B. Azoxystrobin + difenoconazole; fluopyram + tebuconazole
C. Captan alone
D. Streptomycin + copper oxychloride
Answer: B
Rationale: Modern combinations such as azoxystrobin + difenoconazole or fluopyram + tebuconazole have replaced tricyclazole with comparable effectiveness (MDPI, ccari.icar.gov.in).
24. Which rice variety is known for its resistance to bacterial leaf blight (BLB)?
A. IR‑64‑Sub1
B. Pusa Basmati 1121 (original)
C. IR‑20
D. IR‑8
Answer: D
Rationale: The semi-dwarf variety IR‑8 was an early source of bacterial blight resistance; IR‑64 and its derivatives (e.g., Sub1) also carry Xa genes but IR‑8 remains the classic resistant donor (Wikipedia, Wikipedia, Toppr).
25. The improved rice variety Samba Mahsuri (ISM) developed via marker-assisted breeding is characterised by:
A. Submergence tolerance
B. Aromatic grain only
C. Three BLB-resistance genes (Xa21, Xa13, Xa5)
D. Herbicide tolerance
Answer: C
Rationale: ISM carries three bacterial blight resistance genes (Xa21, Xa13, Xa5) while retaining Samba Mahsuri quality traits (rice-garud.icar-web.com, Wikipedia).
26. In many rice fields, the technical moisture content of grain at harvest time is typically:
A. 5–8%
B. 12–14%
C. 15–17%
D. 20–25%
Answer: D
Rationale: At physiological maturity and harvest, grain MC ranges between 20–25% to allow for threshing and transport (appropedia.org).
27. For safe short‑term storage, rice grain moisture should be reduced to below:
A. 9%
B. 12–14%
C. 18%
D. 22%
Answer: B
Rationale: Grain moisture of ≤14% is acceptable for storage up to a few months; <13% or <9% is recommended for longer storage periods (appropedia.org).
28. The famous “Miracle Rice” IR‑8, developed in the 1960s, helped raise yields in Asia from ~1–2 t/ha to:
A. 2–3 t/ha
B. 3–4 t/ha
C. 4–5 t/ha
D. 5–6 t/ha
Answer: C
Rationale: IR‑8 dramatically boosted Asian rice yields to around 4–5 t/ha, contributing to the Green Revolution (Wikipedia).
29. Under moderate submergence (up to ~1 m), the submergence‑tolerant line IR‑64‑Sub1 typically sustains yields of approximately:
A. 1 t/ha
B. 2–2.5 t/ha
C. 3‑3.5 t/ha
D. 5 t/ha
Answer: C
Rationale: IR‑64‑Sub1 can maintain yields of around 3–3.5 t/ha even after up to a week of submergence, thanks to the Sub1 gene (rice-garud.icar-web.com).
30. In drought trials, a stacking of the DRO1 (deeper rooting) gene into IR‑64 resulted in about a 10% yield loss, compared to ~60% in unmodified IR‑64. This indicates:
A. Increased drought sensitivity
B. Partial drought tolerance via deeper roots
C. No yield penalty
D. Yield drop is negligible
Answer: B
Rationale: The DRO1 depth‑rooting gene helped maintain 90% of IR‑64’s potential under drought, whereas unmodified IR‑64 lost ~60% yield (Wikipedia).
31. Sheath blight in tropical Asia typically causes an average yield loss of around:
A. 2%
B. 6%
C. 15%
D. 25%
Answer: B
Rationale: Rice sheath blight has been estimated to reduce yield by ~6% in intensified lowland systems across Asia (International Rice Research Institute).
32. IRRI’s strategy to control blast and other diseases includes:
A. Fungicide-only control
B. Use of resistant varieties and gene stacking
C. Crop rotation only
D. Soil sterilization
Answer: B
Rationale: IRRI employs host resistance breeding, stacking race-specific and quantitative resistance genes to manage blast and other diseases (International Rice Research Institute).
33. Puddling (soil tillage under water) is recommended at:
A. 1 week before sowing/transplanting
B. Just after seeding
C. During harvest
D. At panicle initiation
Answer: A
Rationale: Puddling one week before sowing or transplanting helps conserve moisture, soften soil, and reduce nutrient loss (Infonet Biovision).
34. Which practice is part of SRI to improve soil aeration and nutrient cycling?
A. Continuous flooding
B. No tillage at all
C. Mechanical weeding/aeration
D. Deep puddling
Answer: C
Rationale: SRI uses periodic mechanical weeding, which also aerates the soil, enhancing root growth and microbial activity (ccari.icar.gov.in).
35. A typical rice crop requires approximately 9,200 m³/ha of irrigation for a yield of ~4.5 t/ha under continuous flooding. This number was documented in India and other places.
A. True
B. False
Answer: A
Rationale: Studies in India and Kenya reported water use of ~9,200 m³/ha for yields around 4.5 t/ha under continuous flood regimes (link.springer.com).
36. One week before harvest, draining rice fields is recommended to:
A. Increase grain moisture
B. Soften soil for harvest
C. Improve weed control
D. Boost tillering
Answer: B
Rationale: Draining reduces moisture and hardens soil, making it easier to harvest and helping grain ripening (Infonet Biovision).
37. In rainfed direct-seeded unpuddled lowland rice, blanket fertilizer recommendation is:
A. 40‑20‑20 kg/ha
B. 50‑25‑25 kg/ha
C. 60‑30‑30 kg/ha
D. 80‑40‑40 kg/ha
Answer: B
Rationale: For rainfed lowland rice sown without puddling, 50‑25‑25 kg/ha N‑P₂O₅‑K₂O is recommended (agritech.tnau.ac.in).
38. Leaf Colour Chart (LCC) is commonly used for:
A. Weed identification
B. Herbicide timing
C. Monitoring plant nitrogen status
D. Seed germination check
Answer: C
Rationale: Farmers use LCC to estimate crop nitrogen status and decide N top-dressing timing (agritech.tnau.ac.in).
39. Pre‑transplantation root-dip with chlorpyrifos is used to prevent which pest?
A. Stem borer
B. Gall midge
C. Brown planthopper
D. Leaf folder
Answer: B
Rationale: Nursery seedlings are often root-dipped in chlorpyrifos (≈1 ml/L water) to protect against rice gall midge (icar-nrri.in).
40. Planting single seedlings per hill (instead of clumps) helps in:
A. Decreasing tillering
B. Increasing competition
C. Allowing maximum tiller and root development
D. Reducing spacing flexibility
Answer: C
Rationale: SRI single seedlings per hill with wider spacing reduce plant competition and improve individual tiller vigor and root growth (sri.ciifad.cornell.edu).
41. The most critical water-sensitive stage in rice, where moisture shortage can cause sterility, is between:
A. Germination and first leaf
B. Tillering and active tillering
C. Booting to 14 days after heading
D. Grain hardening and maturity
Answer: C
Rationale: Reproductive stages (booting and early grain fill) are highly moisture sensitive—shortage causes blend with sterility and reduced yield (Infonet Biovision).
42. Which of the following best reduces methane emissions from rice-ecosystems?
A. Continuous flooding only
B. Deep puddling
C. Alternate wetting and drying (AWD)
D. Anaerobic composting
Answer: C
Rationale: AWD (as in SRI) reduces anaerobic conditions, thereby lowering methane emissions compared to continuously flooded paddies (sri.cals.cornell.edu).
43. Among rice pests, the brown planthopper is best managed by:
A. Pre-emergence herbicides
B. Rotating flooded and drained fields
C. Seed treatment with chlorpyrifos
D. Deep ploughing only
Answer: C
Rationale: While not detailed earlier, seed or root-dip insecticides like chlorpyrifos help protect young seedlings from hopper complexes, including gall midge and planthopper (general IPM practice).
44. Yields under SRI are typically:
A. Lower than conventional rice
B. Equivalent to direct-seeded rice
C. 20–50% higher with less inputs
D. 50% higher but with twice the seed
Answer: C
Rationale: SRI practices deliver 20–50% higher yields with significant reductions in seed, water, and fertilisers compared to conventional flooded methods (eBook Icar, plantwiseplusknowledgebank.org, Wikipedia).
45. Which improved Basmati variety has herbicide‑tolerance (tolerant to Imazethapyr), suitable for Direct‑Seeded Rice (DSR)?
A. Pusa Basmati 1121
B. Pusa Basmati 1885
C. Pusa Basmati 1718
D. Pusa Basmati 1979
Answer: D
Rationale: Pusa Basmati 1979 is tolerant to the herbicide Imazethapyr and suitable for DSR cultivation (Wikipedia).
46. Residual seed viability in well-dried rice stored for up to one year should not exceed moisture levels of:
A. 9%
B. 14%
C. 12%
D. 22%
Answer: A
Rationale: For safe seed storage over longer durations (≥ one year), moisture should be reduced to ~9% to prevent deterioration (appropedia.org).
47. Which of the following disease-management strategies is favoured to prevent fungicide resistance?
A. Repeated single-site fungicide only
B. Use of broad-spectrum combinations and resistance genes in varieties
C. Spraying at heading only
D. Drip irrigation
Answer: B
Rationale: To avoid resistance buildup, combining disease-resistant varieties with fungicide mixtures and rotation of modes of action is recommended (PubMed Central).
48. Upland (dry-seeded) local rice varieties use approximately how much fertilizer (N-P₂O₅-K₂O) per hectare?
A. 40‑20‑30 kg/ha
B. 60‑30‑30 kg/ha
C. 100‑60‑60 kg/ha
D. No fertiliser needed
Answer: A
Rationale: For rainfed upland rice under low-fertility conditions, a blanket recommendation of 40‑20‑30 kg/ha is typical (celkau.in).
49. Rice straw or hulls added to paddies can improve soil health by:
A. Increasing weed pressure
B. Reducing aeration
C. Enhancing organic-matter content and soil structure
D. Blocking nutrient uptake
Answer: C
Rationale: Organic residues (including straw, Azolla, green manure) increase fertility, structure, microbial activity, and reduce synthetic inputs (sri.ciifad.cornell.edu, agritech.tnau.ac.in).
50. Which of the following is NOT a benefit typically seen under SRI?
A. Reduced seed use
B. Lower pesticide requirement
C. More continuous flooding
D. Shortened crop cycle
Answer: C
Rationale: SRI replaces continuous flooding with AWD, reducing water usage. It also reduces seed, fertiliser, and often pesticide use, and generally shortens crop duration (sri.cals.cornell.edu, sri.ciifad.cornell.edu).
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