Rice Crop Full Notes

Rice Crop Study Guide – Agriculture Notes
Agronomy

RICE (Oryza sativa L.)

Chromosome Number
2n = 24

1. Introduction & Importance

Botanical Profile

Common NameRice
Botanical NameOryza sativa L.
FamilyPoaceae (Gramineae)
OriginSouth-East Asia (Indo-Myanmar)
PollinationSelf-pollinated (<1% cross)
Photosynthetic PathwayC3 Pathway
Fruit TypeCaryopsis
Edible PortionEndosperm

Global & National Status

World Rank2nd most important cereal (after Maize)
Exporter StatusIndia is the world’s largest exporter
Major Producing StatesWest Bengal, UP, Punjab, Telangana, Andhra Pradesh, Chhattisgarh, Odisha, Tamil Nadu

Nutritional Value (per 100g)

Carbs
78-80%
Protein
6-8%
Fat
0.5-1%
Fibre
0.2-0.5%
Water
10-12%

2. Species & Subspecies

Cultivated Species

Oryza sativa
Asian Cultivated Rice
2n = 24
Oryza glaberrima
African Cultivated Rice
2n = 24

Subspecies of Oryza sativa

SubspeciesCharacteristics
IndicaTropical, long slender grain, India
JaponicaTemperate, short bold grain, Japan/China
JavanicaTropical Japonica, tall plants

3. Climate, Soil & Seasons

Temperature Profile
25–30°C
Optimum growth range
Rainfall Requirement
100–200 cm
Well-distributed rain
Soil Requirements
pH 5.5–7.5
Clay loam to silty clay loam

Critical Stage Temperatures

Germination20–35°C
Flowering25–28°C
Grain Filling20–25°C

Rice Seasons in India

SeasonSowingHarvesting
AusApril–MayJuly–Aug
Aman (Main)June–JulyNov–Dec
BoroNov–DecApril–May

4. Nursery Management & Seed Rates

Types of Nurseries

Wet Nursery
Most common method in India. Suitable for irrigated regions.
Dry Nursery
Perfect for rainfed and upland conditions. Seed is sown on raised beds.
Dapog Nursery
Saves space. Seedlings develop within 10–12 days on non-soil mediums.
Mat Nursery
Thin soil layers facilitate easy mechanical transplanting.

Seed Rate & Spacing

MethodSeed Rate
Transplanted30–40 kg/ha
Direct Seeded (DSR)20–25 kg/ha
Broadcasting80–100 kg/ha
Hybrid Rice10–15 kg/ha
Nursery Area: 1 hectare of crop requires 800–1000 m² nursery.

Chemical Seed Treatment

AgentDosePurpose
Carbendazim2 g/kg seedFungal control
Thiram2.5 g/kg seedSeed protection
T. viride10 g/kg seedBio-control
Azospirillum600 g/ha seedN-Fixation

5. Sowing, Spacing & SRI

Spacing Standards

Normal Transplanting20 × 15 cm
Hybrid Rice20 × 20 cm
SRI Method25 × 25 cm

Seedlings per Hill

HYVs2-3 seedlings
Hybrid Rice1-2 seedlings
SRI Method1 seedling only

System of Rice Intensification (SRI)

Developed By

Fr. Henri de Laulanié (Madagascar)

Seedling Age

8–15 Days

Seed Rate

5–8 kg/ha

Irrigation Mode

Alternate Wetting & Drying

6. Nutrient & Fertilizer Management

Nitrogen (N)
120 kg/ha
Phosphorus (P₂O₅)
60 kg/ha
Potassium (K₂O)
40 kg/ha

Nitrogen Splits

Basal50%
Active Tillering25%
Panicle Initiation25%

Key Micro-Nutrients

Zinc (25kg/ha) Prevents Khaira Disease
Iron (Fe) Prevents Chlorosis
Sulphur (20-30kg) Prevents yellowing

7. Irrigation Management

Water Need

1200-1600 mm

Ideal Standing Depth

2-5 cm

Water Use Efficiency

Low

Most Sensitive Stage

Panicle Initiation (PI)

Critical Sowing Stages & Water Depth Importance

StageDAS (Approx.)Significance
Seedling Establishment0-10Essential for root anchoring
Active Tillering20-30Maximum tiller production period
Panicle Initiation (PI)45-55Most Critical Stage (Do not water-stress)
Booting60-70Underlying panicle formulation
Flowering75-85Ensures smooth pollination & grain set
Milk Stage90-100Starch deposition period

8. Weed Management

Critical Period: 20–45 Days After Sowing (DAS)

Major Weed Varieties

Mimicry Weed
Echinochloa crus-galli (Barnyard Grass)
Looks exactly like young rice seedlings. Great risk factor.
Common Sedges
Cyperus iria (Rice Flat Sedge)

Weed Control Herbicides

HerbicideDoseType
Butachlor 50 EC3 L/haPre-emergence
Pretilachlor 50 EC0.75 kg a.i./haPre-emergence
Bispyribac-sodium200–250 ml/ha15-25 DAS (Post)
2,4-D1 kg a.i./ha30-35 DAS

9 & 10. Plant Protection (Pathology & Entomology)

Major Pathogenic Diseases

DiseaseCausal OrganismDistinct SymptomControl Measure
Blast Magnaporthe oryzae Spindle-shaped eye lesions, neck blast Tricyclazole spray
Brown Spot Bipolaris oryzae Circular dark brown leaf/grain spots Mancozeb, fertilize balanced
Bacterial Blight (BLB) Xanthomonas oryzae Leaf drying from tips; “Kresek” phase Copper bactericides
False Smut Ustilaginoidea virens Green powdery spore-balls on grains Propiconazole spray

Major Insect Pests

Insect PestScientific NameNature of DamageChemical Remedy
Yellow Stem Borer Scirpophaga incertulas Dead heart (vegetative) & White ear (reproductive) Chlorantraniliprole / pheromone traps
Brown Planthopper Nilaparvata lugens Sap sucking, Hopper Burn patches Imidacloprid / Dinotefuran
Green Leafhopper Nephotettix virescens Sap sucking; transmits Rice Tungro Virus Imidacloprid
Gundhi Bug Leptocorisa acuta Sucks milky grains causing chaffiness Malathion dust

11. Harvesting & Storage

Moisture at Harvest 20–24%
Moisture for Safe Storage 12–14%
Grain Color Sign 80-85% Straw Coloured
Milling Recovery 65–70%

12. Important Varieties

DRR Dhan 100 2024

India’s first genome-edited rice variety.

DRR Dhan 52 2022

First heat-tolerant variety developed in India.

DRR Dhan 45 2019

First biofortified variety (High Zinc profile).

Improved Samba Mahsuri 2008

First BLB resistant variety via Marker Assisted Selection.

• Pusa Basmati 1121: Extra-long grain premium Basmati export crop.
• TN-1 (1966): Sourced from Taiwan; first dwarf variety introduced in India.

13 & 14. Key Research Institutes

IIRR

ICAR-Indian Institute of Rice Research

HQ: Hyderabad, Telangana (Est. 2014)

NRRI

ICAR-National Rice Research Institute

HQ: Cuttack, Odisha (Est. 1946)

IRRI

International Rice Research Institute

HQ: Los Baños, Philippines (Est. 1960)

15. High-Yield PYQs

Q: Which family does rice belong to? A: Poaceae (NABARD)
Q: Most critical irrigation stage? A: Panicle Initiation (PI) (IBPS AFO)
Q: What causes ‘Hopper Burn’ in rice fields? A: Brown Planthopper (BPH) (NABARD)
Q: What is the vector of Tungro disease? A: Green Leafhopper (ICAR JRF)
Q: What is the causal agent of Khaira Disease? A: Zinc deficiency (DSSSB)

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