Paddy (Rice) Cultivation: Important Facts & One-Liners 🌾
📌 1. General Introduction & Botany
- Botanical Name: Oryza sativa.
- Family: Poaceae (also known as Gramineae).
- Chromosome Number: 2n = 24 (a normal diploid crop).
- Origin: South East Asia.
- Global Importance: It is the staple food for more than 50% of the world's population.
- Plant Type: It is a C3 plant, a Short-Day plant, and is self-pollinated.
- Root & Stem: It has a fibrous (adventitious) root system, and its hollow, jointed stem is commonly called a culm.
- Inflorescence & Fruit: The inflorescence of rice is known as a panicle, and its fruit type is a caryopsis.
- Test Weight (1000 grains): 24 grams for normal rice, and 21 grams for Basmati rice.
🍛 2. Nutritional Value & Aroma
- Protein Content: Rice contains 6% to 7% protein, which is specifically known as Oryzenin. While low in overall quantity, this protein is rich in lysine.
- Carbohydrates: Contains up to 70% carbohydrates.
- Aroma: The characteristic fragrance in rice (like Basmati) is due to a chemical called 2-acetyl-1-pyrroline.
🌦️ 3. Climate & Soil Requirements
- Climate: Rice thrives in a warm and humid climate, requiring optimum temperatures between 20°C and 35°C.
- Water Requirement: It is a highly water-intensive crop requiring 150 to 200 cm of rainfall. It takes about 5000 liters of water to produce just 1 kg of rice.
- Soil: Clay loam or black soil is considered the best because of its high water-holding capacity.
- pH Level: A slightly acidic soil pH between 4.0 to 6.0 is ideal.
📅 4. Cropping Seasons in India
Rice is grown in three different seasons in India:
- Aus / Autumn (Pre-Kharif): Sown in May-June and harvested in September-October. Covers about 7% of the area.
- Aman / Kharif / Winter (Main Season): This is the most common season, covering 84% of the area. Sown in June-July and harvested in November-December.
- Boro / Spring / Summer: Sown in January-February and harvested in May-June. Only possible in areas with assured irrigation.
🌱 5. Important Varieties & Genetics
- Dwarf Gene: The dwarfing gene responsible for short-stature rice is Dee-geo-woo-gen (DGWG).
- Miracle Rice: IR-8 is globally known as the Miracle Rice, playing a massive role in the Green Revolution.
- First Dwarf Varieties: TN-1 (Taichung Native 1) was the world's first developed dwarf variety. In India, the first high-yielding dwarf variety was Jaya (a cross between T-141 and TN-1).
- First Basmati Semi-Dwarf: Pusa Basmati 1.
- Hybrid Rice:
- Father of Hybrid Rice: Prof. Longping Yuan (China, the first country to develop hybrid rice).
- Father of Hybrid Rice in India: Prof. E.A. Siddiq.
- India's First Hybrid: CORH-1 (developed at TNAU, Coimbatore).
- First Aromatic Hybrid: Pusa RH-10.
- Specialty Varieties:
- Mutant varieties: Jagannath and Prabhavati.
- Salt-tolerant: Lunishree.
- Gall midge resistant: Phalguna.
- BPH (Brown Plant Hopper) resistant: Aruna.
📏 6. Agronomy: Seed Rate & Nursery Management
Seed Rate (per hectare)
- Transplanted Rice: 30 to 40 kg.
- SRI Method (System of Rice Intensification): Only 5 kg.
- Broadcasting: 100 kg.
- Seed Drill: 60 kg.
- Basmati Rice: 20 to 25 kg.
- Hybrid Rice: 15 kg.
Nursery Area & Transplanting Age
- Normal Nursery: Requires 1/10th of the main field area (e.g., 1000 sq meters for a 1-hectare field). Seedlings are transplanted at 25-30 days old (4-leaf stage).
- SRI Method: Requires only 1/100th of the main field area. Seedlings are transplanted very early, at just 12 days old (2-leaf stage) using 1 seedling per hill with 25x25 cm spacing.
- Dapog Method: Developed at IRRI, Philippines. Seedlings are raised without soil in just 25-30 sq meters and are ready in 11 to 14 days.
🚜 7. Field Preparation: The Puddling Process
- What is it? Puddling is the mechanical churning of soil with standing water (5-10 cm deep) using an implement called a puddler.
- Why is it done? It breaks soil clods, mixes weeds into the mud, and most importantly, creates an impermeable layer beneath the surface that prevents water from infiltrating downwards, ensuring the field stays flooded.
💧 8. Fertilizers & Water Management
- NPK Ratio: 100 : 60 : 40 kg/ha.
- Nitrogen Use Efficiency: Very low in rice fields, only around 30% to 40%.
- Best Fertilizer: Ammonium Sulphate is considered the best nitrogenous fertilizer because it performs well in the flooded (reduced) zones of rice fields.
- Khaira Disease: Caused by Zinc deficiency. Controlled by applying 25-30 kg/ha of Zinc Sulphate (ZnSO4).
- Biofertilizers: Blue-Green Algae (BGA) like Anabaena and the water fern Azolla are excellent biofertilizers that can fix 20-25 kg of nitrogen per hectare from the atmosphere.
- Water Management: Standing water is a must! Usually, 1 to 2 inches of standing water is maintained throughout the crop cycle, drained only 15-20 days before harvesting.
🌿 9. Weed Management
- Major Weeds: Echinochloa colonum (Jungle rice) and Echinochloa crus-galli (Barnyard grass) are the most problematic.
- Weed Losses: Cause 10-15% yield loss in transplanted rice and a massive 35-45% loss in direct-seeded upland rice.
- Herbicides:
- Pre-emergence: Butachlor (widely known by its trade name Machete).
- Post-emergence: Propanil (Stam F-34) and 2,4-D.
🏭 10. Harvesting & Processing
- Harvesting Stage: Rice is ready for harvest when the panicles turn golden yellow and the grain moisture content drops to around 20%.
- Milling/Dehulling: Removing the outer husk (glume) from the paddy gives us Brown Rice (unpolished rice), which retains its highly nutritious brown aleurone layer. The hulling percentage is generally 65%.
- Polishing: Removing the brown aleurone layer yields white rice. However, this process results in the loss of important vitamins (especially Vitamin B complex) and the germ/embryo. The removed powder is called bran.
- Parboiling (Hydrothermal Treatment): To save nutrients, paddy is soaked, boiled in steam, and dried before milling. This vital process helps conserve Vitamin B12 that would otherwise be lost during polishing.
