Major Crops: Agronomy, Crop Protection, and Integrated Pest Management for UP TGT and PGT Agriculture

A precise understanding of the botanical classification, origin center, family, and chromosomal constitution (ploidy level) of major field crops forms the foundational basis for competitive agricultural examinations such as UP TGT and PGT Agriculture. Crops are broadly classified into cereals, pulses, oilseeds, and commercial crops.

• Rice (Paddy): Classified as Oryza sativa, belonging to the family Poaceae (Gramineae). Originating in South/Southeast Asia (Indo-Burma region), it possesses a diploid chromosome number of 2n = 24.
• Wheat: Common bread wheat is Triticum aestivum (hexaploid, 2n = 6x = 42), originating in South-West Asia (Near East/Turkey). Durum wheat is Triticum durum (tetraploid, 2n = 4x = 28), and emmer wheat is Triticum dicoccum.
• Maize: Known as the 'Queen of Cereals', Zea mays belongs to family Poaceae with 2n = 20, originating in Central America (Mexico).
• Chickpea (Gram): Cicer arietinum is a self-pollinated pulse crop belonging to family Fabaceae (Leguminosae) with a diploid chromosome number of 2n = 16, originating in South-Western Asia.
• Mustard (Indian Mustard): Brassica juncea belongs to family Brassicaceae (Cruciferae) with 2n = 36, representing an amphidiploid species derived from Brassica nigra and Brassica rapa.

Successful crop establishment dictates yield potential. Agronomic parameters including optimum thermal regimes, seed rates, sowing depths, and crop geometry must be meticulously memorized for competitive examinations.

• Wheat Sowing Geometry: Requires a seed rate of 100 kg/ha for timely sown conditions, increased to 125 kg/ha for late sowing. Optimal row-to-row spacing is 22.5 cm with a sowing depth of 5 cm.
• Rice Nursery Management: For the conventional wet bed method, 40-50 kg of seeds are required for one hectare of main field planting. For the System of Rice Intensification (SRI), seed rate is drastically reduced to 5 kg/ha using single seedlings aged 8-12 days at a wide spacing of 25 cm × 25 cm.
• Maize Plant Population: Optimum plant density is maintained at 65,000 to 75,000 plants per hectare, using a seed rate of 20 kg/ha for grain and 40 kg/ha for fodder, adopting a spacing of 60 cm × 20 cm.
• Soybean Agronomy: Glycine max requires 75 kg/ha seed rate with a spacing of 45 cm × 5 cm, sown at a depth of 3-4 cm in well-drained loamy soils.

Balanced fertilization ensures optimal vegetative growth and reproductive efficiency. Calculations regarding recommended doses of Nitrogen (N), Phosphorus (P₂O₅), and Potassium (K₂O) using commercial fertilizers (Urea, Di-Ammonium Phosphate, Muriate of Potash) are frequently tested in UP PGT examinations.

• Recommended N:P:K for High Yielding Wheat: 120 kg N, 60 kg P₂O₅, and 40 kg K₂O per hectare. Split application of Nitrogen is mandatory: 50% basal at sowing, 25% at Crown Root Initiation (CRI) stage, and 25% at the tillering/jointing stage.
• Fertilizer Calculation Formula: To calculate the quantity of commercial fertilizer required, use the formula:
  Quantity of Fertilizer = (Recommended Nutrient Dose / Percentage of Nutrient in Fertilizer) × 100.
• Urea Calculation Example: If 120 kg N is required per hectare, and Urea contains 46% N, then
  Quantity of Urea = (120 / 46) × 100 = 260.8 kg per hectare.
• DAP Calculation: If 60 kg P₂O₅ is required using DAP (18% N, 46% P₂O₅), then
  Quantity of DAP = (60 / 46) × 100 = 130.4 kg per hectare. This application also supplies 23.4 kg N (130.4 × 0.18), which must be subtracted from the total nitrogen requirement.

Water management is critical for grain filling and preventing physiological stress. Irrigation scheduling based on critical growth stages ensures maximum water use efficiency (WUE).

• Wheat Critical Stages: Crown Root Initiation (CRI) occurring 20-25 days after sowing (DAS) is the most critical stage. Missing irrigation at CRI results in a yield loss of up to 30-40%. Other critical stages include Tillering, Late Jointing, Flowering, Milk stage, and Dough stage (Total 6 irrigations under optimal conditions).
• Rice Critical Stages: Rice is a semi-aquatic plant requiring continuous submergence (5±2 cm) during active vegetative phases, specifically tillering to flowering. Panicle initiation and flowering are most sensitive to moisture stress.
• Maize Sensitivity: Tasseling and silking stages are extremely sensitive to moisture stress. Water deficit during silking leads to poor pollination and barren cobs.
• Chickpea Irrigation: Requires 1-2 light irrigations: first at pre-flowering (branching) and second at pod development stage. Heavy irrigation induces excessive vegetative growth and reduces yield.

Crop protection entails identifying causal organisms, vectors, economic threshold levels (ETL), and applying IPM strategies integrating cultural, mechanical, biological, and chemical controls.

• Rice Blast: Caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae), characterized by spindle-shaped lesions with grey centers and brown margins. Controlled by seed treatment with Tricyclazole 75% WP @ 0.6 g/kg seed.
• Brown Planthopper (BPH) in Rice: Nilaparvata lugens damages the crop by sucking sap from the phloem, causing 'hopper burn'. Natural predators include spiders and microvelia. ETL is 5-10 hoppers per hill.
• Wheat Yellow Rust (Stripe Rust): Caused by Puccinia striiformis, producing yellow pustules in linear rows along leaf veins. Managed through resistant varieties (e.g., PBW 343, DBW 187) and propiconazole sprays.
• Gram Pod Borer: Helicoverpa armigera is a polyphagous pest attacking chickpea, pigeonpea, and tomato. Larvae feed on foliage and bore directly into pods. Managed using Pheromone traps (5 traps/ha) and NPV (Nuclear Polyhedrosis Virus) @ 250 LE/ha.

Determining maturity indices prevents grain shattering and qualitative loss during storage. Proper grain moisture content is vital for safe storage and preventing fungal proliferation.

• Wheat Harvesting Index: Harvested when grain moisture drops to 20-22%, but safe storage moisture content is strictly 10-12%. Yellowing of spikes and hard grains that cannot be dented with a fingernail indicate physiological maturity.
• Rice Harvesting: Harvested when 80-85% of panicles turn straw-colored and grain moisture is around 20-24%. Safe storage moisture is 12-13% for milled rice and 10-11% for seeds.
• Maize Maturity: Indicated by the appearance of a black layer at the base of the grain (placental layer). Safe storage moisture is 12%.
• Storage Pests: Major pests of stored grains include Rice Weevil (Sitophilus oryzae), Khapra Beetle (Trogoderma granarium), and Angoumois Grain Moth (Sitotroga cerealella). Fumigation with Aluminium phosphide (AlP) is standard practice under hermetic storage conditions.