Soil & Water Conservation

• Statement (I) is Correct: Green manuring involves cultivating fast-growing, succulent leguminous or non-leguminous crops (e.g., Crotalaria juncea, Sesbania aculeata) and incorporating them in situ at the tender green stage to enrich soil organic matter, nitrogen, and structure.
• Statement (II) is Incorrect: Green manuring improves soil structure, increases aggregation, reduces bulk density, and enhances water infiltration rates; it is never used to increase compaction or reduce infiltration.
• Conclusion: Statement (I) is correct but Statement (II) is incorrect (Option 3).

• Assertion (A) is Correct: Satellite and airborne remote sensing platforms provide rapid, non-destructive, and spatially comprehensive assessment of crop health, vegetative vigour, and nitrogen status in rainfed agroecosystems.
• Reason (R) is Correct: Distinct spectral reflectance signatures (high green reflectance, strong red chlorophyll absorption, and intense NIR scattering by spongy mesophyll) allow vegetation indices (such as NDVI, GNDVI, NDRE) to correlate strongly with leaf chlorophyll and nitrogen concentrations.
• Relationship: Both statements are accurate, but remote sensing also encounters limitations from cloud cover, mixed pixels, and soil background reflectance in rainfed conditions, making Reason (R) an associated mechanism rather than the absolute cause.
• Conclusion: Both (A) and (R) are correct but (R) is NOT the correct explanation of (A) (Option 2).

• Durum Wheat Leaf Morphology (Option 1): Durum wheat (Triticum durum, tetraploid $2n=28$, AABB) leaves are characteristically broader, stiffer, more erect, and darker green compared to common bread wheat (Triticum aestivum, hexaploid $2n=42$, AABBDD). The assertion that durum leaves are narrower is incorrect, making it the right answer.
• Grain Hardness & Weight (Option 2): Durum wheat grains are flinty, extremely hard, vitreous, and possess higher test weight and thousand-kernel weight than bread wheat.
• Grain Size (Option 3): Durum kernels are typically larger and more elongated than common hexaploid wheat kernels.
• Dough Elasticity (Option 4): Durum wheat gluten has high tenacity but low extensibility and elasticity, making it ideal for pasta, semolina (sooji), and macaroni rather than leavened loaf bread. (Correct answer: Option 1)

• Step 1: Calculate Total Hills per Hectare:

$$\text{Area} = 10,000\text{ m}^2, \quad \text{Spacing} = 0.20\text{ m} \times 0.20\text{ m} = 0.04\text{ m}^2$$ $$\text{Total Hills} = \frac{10,000}{0.04} = 250,000\text{ hills/ha}$$

• Step 2: Seedlings Required for Planting:

$$\text{Seedlings needed in main field} = 250,000 \times 2 = 500,000\text{ seedlings}$$

• Step 3: Account for 20% Uprooting Damage:

$$\text{Total seedlings required in nursery} = \frac{500,000}{1 - 0.20} = \frac{500,000}{0.80} = 625,000\text{ seedlings}$$

• Step 4: Account for Germination (90%) and Purity (90%):

$$\text{Real Value of Seed} = 0.90 \times 0.90 = 0.81$$ $$\text{Total seeds to be sown} = \frac{625,000}{0.81} \approx 771,605\text{ seeds}$$

• Step 5: Calculate Seed Rate using Test Weight (25 g per 1000 seeds):

$$\text{Seed Rate (kg/ha)} = \frac{771,605 \times 25\text{ g}}{1000 \times 1000} = 19.29\text{ kg/ha} \approx 19.3\text{ kg/ha}$$

• Conclusion: The required seed rate is 19.3 kg/ha. (Correct answer: Option 4)