UPSC Agriculture 2026 — Paper II

(a) Two linked demands: (i) define somatic (protoplast) hybridization, and (ii) explain, in sequence, the steps by which a somatic hybrid plant is produced. The bulk of the marks lie in the ordered protocol, not in the definition. (b) A single demand: list and explain the biochemical (not merely physical) changes that accompany seed deterioration during prolonged storage. The answer must be organised by class of biochemical change - lipids, membranes, enzymes/proteins, nucleic acids, reserves and antioxidants - and link them to loss of vigour and viability. (c) Describe the factors that govern how much of a nutrient a plant root actually takes up from soil. A complete answer treats the mechanism of arrival at the root (mass flow, diffusion, interception), soil factors, plant factors and management factors. (d) Describe the defining genetic and breeding characteristics of a clone. The examiner expects the genetic consequences of asexual propagation - identity, retained heterozygosity, absence of segregation, environmental-only variation within a clone, mutation and clonal degeneration - each stated as a property, with crop examples. (e) Two demands: define a mutagen, and then explain the different groups of mutagens. The grouping must be systematic - physical (ionizing and non-ionizing) and chemical (alkylating agents, base analogues, intercalating/acridine dyes, deaminating and other agents) - with named examples and the kind of change each causes.

• Definition: fusion of protoplasts of two plants and regeneration of a hybrid
• Isolation of protoplasts with enzymes in osmoticum
• Fusion (PEG, electrofusion), selection of hybrids, culture and regeneration
• Verification of hybrid and example such as pomato; cybrids
• Lipid peroxidation and membrane damage with leakage
• Hydrolysis of lipids to free fatty acids and loss of enzyme activity
• Protein denaturation, DNA damage, loss of respiration and ATP
• Effect of moisture and temperature on ageing
• Plant factors: root system, root hairs, root CEC, mycorrhiza, growth stage, energy
• Soil factors: nutrient concentration, moisture, aeration, temperature, pH
• Ion interactions: antagonism and synergism
• Mechanisms of contact: mass flow, diffusion, root interception
• Definition: genetically identical individuals from a single plant by vegetative propagation
• Uniform and true to type; heterozygosity preserved
• Multiplied by vegetative means; examples such as potato, sugarcane, banana
• Variation only by somatic mutation; disease carry-over; narrow base
• Definition: physical or chemical agents raising mutation frequency
• Physical: ionising radiation (X, gamma, neutrons) and ultraviolet
• Chemical: alkylating agents (EMS), base analogues, acridine dyes, nitrous acid, azide
• Use in mutation breeding, with an example variety

(a) Two distinct halves must be answered: the CAUSES of disease resistance (the structural, biochemical and genetic mechanisms by which a plant resists a pathogen) and the SOURCES of resistance (where a breeder obtains resistance genes). Omitting either half forfeits roughly half the marks. (b) Explain both the structure and the functions of the mitochondrion, and a labelled diagram is explicitly demanded, so its absence is penalised. Structure must cover the double membrane, cristae, matrix and mitochondrial genome; functions must go beyond 'powerhouse' to include the specific plant mitochondrial roles. (c) Describe why molecular markers matter in crop improvement. The answer must define a molecular marker, name the main marker classes, and then set out the concrete uses - marker-assisted selection and backcrossing, gene pyramiding, QTL mapping, fingerprinting and purity testing - preferably with named Indian examples of MAS-derived varieties.

• Causes: structural barriers (cuticle, wax, thick walls, stomata) and pre-formed biochemical defences
• Induced defences: HR, phytoalexins, PR proteins, SAR
• Genetic basis: vertical (R genes, gene-for-gene) versus horizontal (polygenic, durable) resistance
• Sources: cultivars and landraces, wild relatives, germplasm, mutation, and genetic engineering or genome editing
• Double membrane: smooth outer, folded inner with cristae, intermembrane space and matrix
• Matrix holds Krebs cycle enzymes, mtDNA and 70S ribosomes; inner membrane carries the electron transport chain and ATP synthase
• Main function: ATP production through the Krebs cycle and oxidative phosphorylation
• A labelled diagram showing the membranes, cristae and matrix
• Definition of a molecular marker with examples (RFLP, SSR, SNP)
• Marker-assisted selection, especially for recessive or late-expressing traits
• Gene mapping and QTL analysis, and marker-assisted backcrossing and gene pyramiding
• Germplasm characterisation, DNA fingerprinting and seed purity

(a) Three sequential demands: define heritability; distinguish broad-sense from narrow-sense heritability (with their variance formulae); and explain the applications of heritability in crop improvement. All three must be present, and the formulae with the partitioning of variance are the core of the second part. (b) Discuss both the PRINCIPLES (genetic and agronomic) and the PRACTICES of seed production, and do so comparatively for self-pollinated and cross-pollinated crops. An answer that treats only one pollination group, or only principles, loses half the marks. (c) Three demands in one short note: define cytoplasmic inheritance, and explain briefly sex-influenced traits and sex-limited traits. Roughly half the marks belong to cytoplasmic inheritance and half to the two kinds of sex-associated traits, which must be clearly distinguished from each other and from sex-linked inheritance.

• Definition: proportion of phenotypic variance due to genetic variance
• Broad sense V_G/V_P versus narrow sense V_A/V_P, with the difference explained
• Applications: predicting genetic advance (R = h²S), choice of selection method and generation
• Cautions: population and environment specific; high heritability does not mean high gain
• Principles: genetic purity, suitable agronomic conditions, isolation, rogueing, quality standards
• Seed classes: breeder, foundation, certified, under the Seeds Act, 1966
• Self-pollinated crops: small isolation distance, rogueing, separate harvest
• Cross-pollinated crops: larger isolation (about 400 m or 200 m in maize), row ratio, detasseling or CMS, synchronised flowering
• Cytoplasmic inheritance: organelle genes, maternal transmission, non-Mendelian, reciprocal difference
• Example such as Mirabilis variegation or CMS
• Sex-influenced: autosomal genes whose dominance depends on sex (baldness, horns in Dorset sheep)
• Sex-limited: expressed in one sex only (milk yield, egg production)

(a) Discuss what makes seed marketing difficult and risky to run at a profit. The answer must be built on the peculiar nature of seed as a commodity (living, perishable, seasonal, produced a year or more in advance) and then cover demand forecasting, inventory and carry-over, finance, competition and the legal-regulatory burden, ending with mitigation measures. (b) Explain what determines the AMOUNT of soil water that is available to plants - that is, the water held between field capacity and permanent wilting point within the root zone. The answer must first define available water with its potential limits, then cover soil physical, soil chemical, profile and plant/atmospheric factors. (c) Two linked demands: describe the seed enhancement techniques used by the seed industry, and state their benefits. Enhancement means post-harvest, pre-sowing treatments that improve performance without altering the genotype - priming, coating and pelleting, treatment and fortification, and physical upgrading.

• Perishability and seasonality of seed; unsold stock loses viability
• Uncertain demand tied to monsoon, prices and variety choice
• Farm-saved seed, low replacement rate, and spurious or sub-standard seed hurting trust
• Regulation (Seeds Act 1966, Seeds Control Order 1983, PPV&FR Act 2001), infrastructure, credit and production risk
• Available water = field capacity minus permanent wilting point, with values (−33 kPa, −1500 kPa)
• Soil texture, structure and organic matter
• Soil and rooting depth, compaction, layers and salinity
• Water supply and losses (rain, irrigation, runoff, evaporation), crop, weather and water table
• Definition: post-harvest treatments to improve germination, emergence or handling
• Priming (hydro, osmo, halo, matrix, bio) and hardening
• Pelleting, film coating and seed treatment with fungicides or bio-agents
• Benefits: uniform emergence, stand, stress tolerance, pest protection, precise sowing

(a) Two demands: define topiary, and describe the characteristics that make a plant ideal for topiary. The second half carries most of the marks and must list plant attributes (leaf size, branching habit, response to hard pruning, growth rate, hardiness) with named suitable species. (b) Two independent sub-parts of equal weight: describe a terrace garden, and describe a moon garden. Each needs its definition, its design/technical requirements and its characteristic plants; neither may be omitted. (c) Discuss the quality indices - the attributes by which market and consumer quality are judged, including maturity indices and quality-destroying defects and disorders - separately for cauliflower (curd), cabbage (head) and broccoli (sprouting head). All three crops must be covered. (d) Discuss the constraints - not the achievements - that limit further growth of foodgrain production in India. A strong answer classifies them (natural resource, technological, institutional/economic, climatic and policy) and supports each with a concrete Indian figure or example. (e) Discuss what osmoprotectants are and what they do for plants specifically under salt stress and water (drought) stress. The answer must define compatible solutes and their properties, name the main chemical classes with example compounds, and explain their protective functions beyond simple osmotic adjustment.

• Definition: clipping and training live plants into ornamental shapes
• Small, dense, evergreen foliage
• Tolerance to repeated clipping, quick recovery, budding from old wood, slow compact growth
• Examples such as boxwood, Duranta, Murraya, Ficus
• Terrace garden: roof-top garden; load check, waterproofing, drainage, light medium, containers
• Terrace garden benefits: cooling, energy saving, food, run-off reduction
• Moon garden: for night viewing; white or pale flowers and silver foliage
• Night-blooming fragrant plants (raat ki rani, night jasmine, tuberose, moonflower)
• Cauliflower curd: compact, white, uniform, free from riceyness, fuzziness and browning
• Cabbage head: firm, compact, right size and shape, no splitting or tipburn
• Broccoli head: tight, dark green, small uniform buds, no yellowing or open flowers
• Freshness and freedom from insect and disease damage as common indices
• Small and fragmented holdings
• Soil degradation and imbalanced fertiliser use
• Water scarcity, groundwater decline and dependence on monsoon; climate variability
• Yield plateau, pests and diseases, quality seed, post-harvest losses, credit and extension
• Definition: small, soluble, non-toxic compatible solutes (proline, glycine betaine, trehalose, mannitol)
• Osmotic adjustment to maintain turgor and water uptake
• Protection of proteins, enzymes and membranes; ROS scavenging
• Engineering or exogenous application to raise tolerance

(a) Two linked parts: first define high density orcharding/planting (HDP) and give its density classes and rationale; then 'describe' - give a full account of the management practices that make HDP work specifically in the citrus group (mandarin, sweet orange, acid lime), covering rootstock, spacing/planting system, canopy management, fertigation, growth regulation and plant protection. (b) Two parts, both compulsory: (i) 'explain' the biosynthetic pathway of chlorophylls and, separately, of carotenoids - the substrates, the key intermediates, the named enzymes and the branch points; and (ii) explain how environmental factors - light, temperature, water, mineral nutrition, salinity, pollutants - influence the level and composition of plant pigments. (c) Two parts: define what nutrient deficiency in humans means (including the distinction between macronutrient/protein-energy deficiency and micronutrient 'hidden hunger'), and then list and briefly explain the major causes of nutrient deficiencies in India. A compact note, not an essay.

• Definition: more trees per unit area with dwarfing or compact plants and canopy control; citrus spacing figures (about 3 × 3 m versus 6 × 6 m)
• Dwarfing rootstocks and certified disease-free planting material
• Training and pruning to limit height; drip irrigation with fertigation
• Bahar regulation, pest management (psylla, canker, greening), advantages and limits
• Chlorophyll: glutamate to ALA (C5), PBG, uroporphyrinogen III, protoporphyrin IX, Mg-chelatase, protochlorophyllide
• Light-dependent POR step, chlorophyllide a, chlorophyll synthase and chlorophyll b
• Carotenoid: MEP/IPP, GGPP, phytoene, lycopene, cyclisation to α- and β-carotene, xanthophylls
• Environmental effects: light, temperature, water, nutrients (N, Mg, Fe), stress and senescence
• Definition: inadequate supply or absorption of nutrients for normal health; macro and micronutrient deficiency (hidden hunger)
• Causes: poverty, cereal-based monotonous diet, poor soils and processing losses
• Poor absorption from infections and sanitation; maternal and child feeding practices
• Awareness, gender and health access; a data point such as NFHS-5 anaemia or stunting

(a) 'Describe' the scientific cultivation of mango, but only under the five heads the examiner has specified and in that order: regular bearing varieties, propagation, time of transplanting, management of mango mealy bug, and management of powdery mildew. All five must be covered; marks are lost for a general essay on mango. (b) Two parts: identify and explain the major causes of poverty in India, and then 'describe' - explain with mechanisms and evidence - the role agriculture plays both in alleviating poverty and in generating employment. The answer must connect the causes to the agricultural remedy rather than presenting two unrelated lists. (c) Two parts: 'explain the different types of seed dormancy' - a classified account with examples, not a bare list - and then state the factors responsible for dormancy. Keep it to the compass of a 150-word note while still naming the classes and the causal factors.

• Regular bearers (Neelum, Banganapalli, Totapuri, Mallika, Amrapali, Ratna, Arka Puneet) versus alternate bearers
• Propagation by veneer or softwood grafting on seedling rootstocks in the monsoon
• Planting time (onset of monsoon, July–August), pit preparation and spacing
• Mealy bug (Drosicha) control: raking in Nov–Dec, polythene band, insecticide, natural enemies; powdery mildew (Oidium): wettable sulphur or systemic fungicide, three sprays
• Causes: low agricultural productivity, unemployment and underemployment, population pressure, inequality
• Causes: illiteracy, poor health, caste, gender and regional disparities, credit and market gaps, vulnerability to shocks
• Role of agriculture: employment of about 46% of workforce, farm income, food security
• Diversification (horticulture, dairy, fisheries, agro-processing), rural wage employment and growth linkages
• Primary and secondary dormancy
• Physical, physiological, morphological, morphophysiological and combinational types
• Factors: impermeable or hard seed coat, immature embryo, after-ripening or chilling need
• Factors: inhibitors (ABA, phenolics), lack of promoters (GA), light and temperature

(a) Two linked parts: 'explain' the factors - physical, biological, structural and managerial - that encourage insect pest infestation of stored produce, and then 'discuss' the control measures, which means a reasoned account of preventive/prophylactic, physical, chemical (including fumigation with doses), biological and hermetic/IPM measures rather than a bare list. (b) 'Discuss' the production technology of carnation as a cut flower under five heads the examiner has explicitly listed - improved varieties, growing requirements and season, flower regulation, post-harvest handling, and physiological disorders. All five heads must appear; an answer that covers only cultivation practices cannot pass. (c) 'Discuss' the steps the Government of India has taken to improve the food processing industry - the ministry and the major schemes with their purpose, plus the fiscal, regulatory and infrastructure measures. A compact, well-organised note naming actual schemes is required, not a general argument about why processing matters.

• Factors: grain moisture, temperature, humidity
• Factors: initial infestation, poor hygiene, damaged grain, storage structure and duration
• Preventive control: drying, sanitation, disinfection of stores, hermetic storage, rodent-proofing
• Curative control: phosphine fumigation, botanicals or inert dusts, controlled atmosphere; IPM with monitoring
• Improved varieties: standard and spray types with examples
• Growing requirements: cool bright climate, night 10–12 °C, polyhouse, soil pH 6–7, planting season and spacing
• Flower regulation: single, one-and-half and double pinching; disbudding; light and temperature
• Post-harvest: stage of harvest, grading, cooling, ethylene protection (STS), storage; disorders: calyx splitting with causes and remedies
• PM Kisan SAMPADA Yojana (2017) and its components, mega food parks and cold chain
• PLI scheme for food processing (₹10,900 crore) and PMFME (One District One Product)
• Agriculture Infrastructure Fund and finance through NABARD; 100% FDI through the automatic route
• Food safety (FSSAI), export promotion and Operation Greens