Cotton (Gossypium sp.)

Basic Information

• Botanical Name: Gossypium species
• Family: Malvaceae
• Origin: India
• Common Name: White Gold
• Growth Habit: Annual plant with a taproot system
• Importance: Known as the King of Appraisal Fibre due to its global economic significance
• Fruit (Boll): A capsule with 3–5 locules, each having 5–8 seeds covered in lint (long fibers) and fuzz (short fibers).

Climate Requirement

• Type: Tropical and subtropical crop
• Temperature: Optimum 21–30°C; sensitive to frost
• Rainfall: 500–1000 mm (well-distributed)
• Sunlight: High requirement for sunshine, 6–8 hours/day

Soil Requirement

• Well-drained black cotton soil (Regur) is ideal
• pH: 6.0–7.5; can tolerate slight salinity

Land Preparation

• Deep ploughing followed by 2–3 harrowings
• Fine tilth required for proper seed placement

Sowing Time

• Kharif Season: June–July (depends on monsoon)
• Spacing: 60×30 cm for varieties; 90×60 cm for hybrids

Seed Rate

• Varieties: 15–20 kg/ha
• Hybrids: 3–5 kg/ha

Seed Treatment

• Fungicide: Carbendazim or Thiram (2.5 g/kg)
• Biofertilizer: Azospirillum and Phosphobacteria

Classification of Cotton

There are around 20 species of cotton, but only 4 are cultivated commercially:

• (A) Desi / Asiatic Cotton (Diploid, 2n = 26) Gossypium arboretum. Gossypium herbaceum
• (B) American / Egyptian Cotton (Tetraploid, 2n = 52) Gossypium hirsutum, Gossypium barbadense

➡ India is the only country where all four species are commercially cultivated.

🔸 Contribution in Indian Cultivation Area:

• Hybrid Cotton: 40%
• Gossypium arboreum: 36%
• Gossypium herbaceum: 16%
• Gossypium hirsutum: 08%
• Gossypium barbadense: 0.2%

Bt Cotton (Genetically Modified Cotton)

Bt (Bacillus thuringiensis): A soil bacterium whose genes (Cry genes) are inserted into cotton to develop resistance against bollworms.

• Gene Used: Cry1Ac (affects insect digestive system)
• First Developed Bt Cotton in India: Bollgard I, Developed by Mahyco-Monsanto using Cry1Ac gene
• Bollgard II (2006): Contains Cry1Ac + Cry2Ab genes for better resistance

Benefits of Bt Cotton:

• Reduces insecticide usage by over 50%
• Controls bollworms, major cotton pests
• Approved by Genetic Engineering Approval Committee (GEAC) under Ministry of Environment & Forests
• The first generation GM crops (Cotton, Maize, Potato) were approved in 1995 and commercialized in 1996

Cotton Area and Production

• In the World: Area: India > USA > China, Production: China > USA > India
• In India: Area: Maharashtra > Andhra Pradesh > Gujarat, Production: Maharashtra > Andhra Pradesh > Haryana

 Important Cotton Varieties

• Gossypium arboreum: Lohit
• Gossypium herbaceum: Digvijaya
• Gossypium hirsutum: Ganganagar Agety, Mahalaxmi
• Gossypium barbadense: Sujata, Suvin

Hybrid Cotton Varieties

• H-4 (Hybrid-4): Developed by C.T. Patel, Gujarat Agricultural University, Surat (1970), First commercial hybrid cotton variety, Cross between G-67 × American Nectarless
• Varalaxmi: First interspecific hybrid between hirsutum × G. barbadense, Released by UAS Dharwad, Karnataka
• Other Hybrid Varieties: Savita, Surya – Intraspecific hybrids of hirsutum, Dhanlaxmi

Branching in Cotton

1. Monopodial Branches: Arise from axillary buds. Vegetative in nature
2. Sympodial Branches: These are the reproductive branches, Responsible for flower and boll formation

Delinting in Cotton

• Delinting/Defuzzing: A seed treatment process
• Chemical Used: Concentrated sulphuric acid
• Ratio: Acid to seed = 1:10

Purpose of Delinting:

• Removes lint or fuzz from seeds
• Helps in grading the seeds
• Destroys seed-borne pathogens
• Makes seeds easier to handle, sow, and germinate quickly

Fertilizer Requirement (Per hectare)

• NPK Recommendation:
  • For irrigated hybrid: 100–120 kg N, 50 kg P₂O₅, 50 kg K₂O, Apply in split doses for better utilization
• Micronutrients: Zn, B, and Mg application improves yield and boll development

Irrigation

• Critical Stages:
  1. Germination
  2. Flowering
  3. Boll formation
• Avoid waterlogging; prefer furrow irrigation
• In drip systems: Water-use efficiency increases

Major Pests of Cotton

1. Bollworm (Helicoverpa armigera): Most damaging; controlled by Bt cotton
2. Aphids & Whiteflies: Vectors of cotton leaf curl virus
3. Jassids (Leaf hoppers): Cause leaf curling and stunting
4. Mealybugs: Sap-sucking pest; sticky honeydew leads to sooty mold
5. Pink Bollworm (Pectinophora gossypiella): Larvae feed inside the boll

Control Measures:

• Integrated Pest Management (IPM)
• Use of pheromone traps, neem extracts, and bioagents like Trichogramma

Major Diseases of Cotton

1. Bacterial blight (Xanthomonas campestris): Leaf spot, stem canker
2. Fusarium wilt: Yellowing, stunting, wilting
3. Verticillium wilt
4. Alternaria leaf spot

Control Measures:

• Use of disease-resistant varieties
• Crop rotation and seed treatment
• Avoid water stagnation

Harvesting and Yield

• Maturity Period: 150–180 days
• Harvesting: Done manually in 3–4 pickings as bolls open
• Avoid harvesting during rain or dew

Average Yield:

• Desi Varieties: 10–12 quintals/ha
• Hybrids: 15–20 quintals/ha
• Bt Hybrids: 25–35 quintals/ha (under proper management)

Post-Harvest Practices

• Ginning: Removal of lint from seed using ginning machines
• Lint Quality: Depends on fiber length, strength, and fineness, Long Staple (>27 mm): Preferred for high-quality fabric
• Grading: Seeds and lint are graded based on color, staple length, and cleanliness

Economic Importance of Cotton

• Major Cash Crop: Supports textile industry
• Provides raw material for yarn, cloth, oil, and animal feed
• Cottonseed oil is edible; seed cake used as animal feed
• Lint export: Significant contributor to foreign exchange