UPHESC Assistant Professor Agronomy PYQs

Concept: Bispyribac-sodium (ALS inhibitor) is a post-emergence herbicide for rice (DSR and transplanted) at 20–25 g a.i./ha, 15–25 DAS.

1. Controls Echinochloa, sedges and broadleaf weeds.
2. Wheat uses sulfosulfuron/clodinafop; maize – atrazine/tembotrione.

Short trick: Bispyribac = paddy post-emergence.

Concept: Panicum repens (torpedo grass) is a perennial grass with an extensive creeping rhizome network that binds soil on slopes and bunds.

1. Convolvulus arvensis – bindweed, a problem weed of field crops.
2. Amaranthus viridis, Digera arvensis – annual broadleaf weeds with little soil-binding value.

Short trick: Rhizomatous grasses (Panicum repens, Cynodon) = soil binders.

Concept: Leucas aspera (Thumbai/Guma) leaf juice is used in folk medicine against snake bite and scorpion sting.

1. Phyllanthus niruri (bhui-amla) – jaundice/liver.
2. Abutilon indicum (kanghi) – piles, demulcent; Trianthema – a common kharif weed.

Short trick: Leucas – snake bite; Phyllanthus – liver.

Concept: In drylands crop yields are risky; combining field crops with livestock (dairy, goat, sheep) stabilises income and recycles residues and manure.

1. Fisheries need assured water – unsuitable for dry areas.
2. Crops alone carry the full risk of drought.

Short trick: Dryland IFS = crop + livestock.

Concept: C₄ plants carboxylate twice: first in mesophyll on phosphoenol pyruvate (by PEP carboxylase), then in bundle sheath by RuBP carboxylase (RuBisCO) in the Calvin cycle.

1. Option (A) names the PEP system (PEP carboxylase acting on phosphoenol pyruvate).
2. Both carboxylations are essential, so 'Both (A) and (B)'.

Short trick: C₄ = PEPcase (mesophyll) + RuBisCO (bundle sheath).

Concept: C, H and O (from CO₂ and water) make up about 94–96% of plant dry matter.

1. The remaining ~4–6% is mineral nutrients (N, P, K etc.) – the ash.
2. C ≈ 45%, O ≈ 45%, H ≈ 6%.

Short trick: C-H-O ≈ 96%; minerals ≈ 4%.

Concept: PAR (400–700 nm) is measured with a quantum sensor as photosynthetic photon flux density (µmol m^-2 s^-1); a line quantum sensor measures canopy interception.

1. Pyranometer/solarimeter – total solar radiation.
2. Thermal sensors measure temperature.

Short trick: PAR → quantum (photon) sensor.

Concept: Sun-synchronous satellites are near-polar, low-orbit satellites crossing a place at the same local solar time – used for earth resources (Landsat, IRS, SPOT).

1. GOMS/METEOSAT, INTELSAT and INSAT are geostationary (≈ 36,000 km).
2. Landsat is used for crop acreage and land-use mapping.

Short trick: Resource satellites (Landsat/IRS) = sun-synchronous; communication/weather (INSAT) = geostationary.

Concept: Radiation transfers energy as electromagnetic waves and needs no medium – that is how solar energy crosses space.

1. Conduction – molecule to molecule in solids.
2. Convection – mass movement of fluids (air/water).

Short trick: Sun's heat reaches us through vacuum → radiation.

Concept: Coppicing: trees cut near ground regenerate many shoots from the stump; repeated harvests on short rotation = coppice farming.

1. Examples: Leucaena, Eucalyptus, Sesbania, willow, poplar.
2. Energy plantations often use coppice species, but the practice described is coppicing.

Short trick: Stump re-sprouts → coppice.

Concept: Growing two or more crops a year on the same land (intensity > 200%) is realistically possible only where assured irrigation is available.

1. Water-scarce areas support one crop at most.
2. High rainfall alone is seasonal and cannot support the rabi/summer crops.

Short trick: Multiple cropping = assured water + inputs.

Concept: SYI $=\frac{\overline{Y}-\sigma }{Y_{max}}$ – measures the sustainability (stability of yield over years) of a cropping system.

1. Higher SYI (towards 1) = more sustainable.
2. Economic feasibility is judged by B:C ratio; production efficiency by kg/ha/day.

Short trick: SYI = (mean − SD)/max yield → sustainability.

Concept: Stress resistance (Levitt) is the overall ability to survive stress and includes both avoidance and tolerance mechanisms.

1. Escape – completing life cycle before stress (early maturity).
2. Avoidance – keeping tissue free of stress; Tolerance – enduring stress in tissue.

Short trick: Resistance = Avoidance + Tolerance.

Concept: Earth's radiative equilibrium temperature without greenhouse gases ≈ −18 °C; actual mean ≈ +15 °C.

1. The natural greenhouse effect therefore adds about 33 °C.
2. Main natural greenhouse gases: water vapour, CO₂.

Short trick: −18 → +15: a 33 °C blanket.

Concept: Maize is a C₄ crop (also sorghum, sugarcane, pearl millet).

1. Rice, wheat and soybean are C₃.
2. C₄ plants have Kranz anatomy and no apparent photorespiration.

Short trick: C₄ = Maize, Sorghum, Sugarcane, Bajra.

Concept: Solar constant – energy received on a unit area perpendicular to the sun's rays at the top of the atmosphere at mean Earth–Sun distance ≈ 1.94 cal cm^-2 min^-1 (≈ 1367 W m^-2).

1. The unit must be energy per area per time – only option (C) has it.
2. Some texts round it to 2.0 langley/min.

Short trick: Solar constant ≈ 1.94 ly/min ≈ 1367 W/m².

Concept: Subabul (Leucaena leucocephala) is a leguminous, N-fixing, fast-growing fodder and fuel tree.

1. Mango, neem and orange are non-leguminous.
2. Subabul leaf contains mimosine – feed in limited quantity.

Short trick: Subabul = legume + fodder + fuel.

Concept: Pea shows hypogeal germination – cotyledons remain below the soil because the epicotyl elongates.

1. Hypogeal: pea, gram, maize, rice, wheat.
2. Epigeal: bean, groundnut (partly), soybean, cotton, castor.

Short trick: Pea pushes its shoot up, cotyledons stay down = hypogeal.

Concept: Berseem (Egyptian clover, Trifolium alexandrinum) was introduced into India from Egypt in 1904 (first grown in Sind).

1. It is the 'king of fodders' – multi-cut rabi legume.
2. Scientific name honours Alexandria (Egypt).

Short trick: Egyptian clover → from Egypt.

Concept: Blackgram (Vigna mungo) originated in India (Hindustan centre of Vavilov).

1. Greengram also originated in India.
2. Tropical America – groundnut, maize; China – soybean.

Short trick: Urd & Moong – Indian natives.