Cotton (Gossypium spp.) – “White Gold”

1. Basic Information

• Botanical name: Gossypium spp.
• Family: Malvaceae
• Origin: India (arboreum), Africa (herbaceum), Central America (hirsutum), Peru (barbadense).
• Growth habit: Annual with a taproot system.
• Fruit (boll): Capsule with 3–5 locules, each having 5–8 seeds covered by lint (long fibre) and fuzz (short fibre).
• Importance:
  • Known as “White Gold” and “King of Apparel Fibre”.
  • Dual purpose crop → fibre + edible oil.
  • Cottonseed oil: 18–24%.

2. Climate Requirements

• Type: Tropical and subtropical crop.
• Optimum temperature: 21–30°C; sensitive to frost.
• Rainfall: 500–1000 mm, well-distributed.
• Sunshine: Needs 6–8 hrs/day.
• Requires dry climate at boll opening & harvest.

3. Soil Requirements

• Ideal: Well-drained black cotton soils (Regur, Vertisols).
• Also suitable: Loam soils with good fertility.
• pH: 6.0–7.5 (tolerates slight salinity).

4. Land Preparation; Deep ploughing + 2–3 harrowings. Fine tilth ensures uniform germination.

5. Sowing

• Time: Kharif (June–July, with monsoon). Summer (Feb–March, irrigated).
• Spacing: Varieties: 60 × 30 cm. Hybrids: 90 × 60 cm.
• Seed rate: Varieties: 15–20 kg/ha. Hybrids: 3–5 kg/ha.
• Seed treatment: Fungicide: Carbendazim or Thiram (2.5 g/kg). Biofertilizer: Azospirillum + Phosphobacteria.
• Delinting: Conc. H₂SO₄, seed:acid = 1:10. → Removes fuzz, kills pathogens, improves handling.

6. Classification of Cultivated Cotton

• ~20 species exist; only 4 commercially cultivated:
  • Diploids (2n=26): G. arboreum (Asiatic/desi cotton). G. herbaceum.
  • Tetraploids (2n=52): G. hirsutum (Upland cotton, 90% world area). G. barbadense (Egyptian cotton, extra-long staple).
• India: only country cultivating all 4 species.

7. Area and Production

• World: Area: India > USA > China. Production: China > USA > India.
• India (2023):
  • Area: ~12.5 million ha.
  • Production: ~33 million bales (1 bale = 170 kg).
  • States: Maharashtra > Gujarat > Andhra Pradesh > Telangana > Haryana.
• Area share in India:
  • Hybrids: 40%
  • G. arboreum: 36%
  • G. herbaceum: 16%
  • G. hirsutum: 8%
  • G. barbadense: 0.2%

8. Bt Cotton

• Bt gene: from Bacillus thuringiensis.
• Cry1Ac gene → Bollgard I (resistant to bollworms).
• Cry1Ac + Cry2Ab genes → Bollgard II (2006).
• Benefits: Reduces insecticide use by 50%. Controls bollworms effectively.
• Approved by GEAC (Govt. of India).

9. Varieties and Hybrids

• G. arboreum: Lohit.
• G. herbaceum: Digvijaya.
• G. hirsutum: Ganganagar Agety, Mahalaxmi.
• G. barbadense: Sujata, Suvin.
• Hybrids:
  • H-4 (1970, Surat GAU): First commercial hybrid (G-67 × American Nectarless).
  • Varalaxmi: First interspecific hybrid (hirsutum × barbadense).
  • Other: Savita, Surya, Dhanlaxmi.

10. Morphology

• Monopodial branches → vegetative.
• Sympodial branches → reproductive (bearing flowers/bolls).

11. Fertilizer Requirement (kg/ha)

• Rainfed: 60–80 N + 30–40 P₂O₅.
• Irrigated hybrid: 100–120 N + 50 P₂O₅ + 50 K₂O.
• Micronutrients: Zn, B, Mg beneficial for boll setting.
• Apply in split doses for efficient use.

12. Irrigation;

• Critical stages: Flowering. Boll formation.
• Avoid waterlogging.
• Drip irrigation enhances WUE.

13. Weed Management

• Critical period: 30–60 DAS.
• 2 intercultivations + earthing-up.
• Herbicides: Pendimethalin @ 1.0 kg a.i./ha (PE), Quizalofop (grassy weeds).

14. Pests and Diseases

• Major pests:
  • Bollworms (Helicoverpa, pink bollworm, spotted bollworm).
  • Aphids, jassids, whitefly (vector of cotton leaf curl virus).
  • Mealybugs.
• Major diseases:
  • Bacterial blight (Xanthomonas campestris).
  • Fusarium wilt.
  • Verticillium wilt.
  • Alternaria leaf spot.
• Control: Resistant varieties, crop rotation, seed treatment, IPM (pheromone traps, neem, Trichogramma).

15. Harvesting and Yield

• Maturity: 150–180 days.
• Harvesting: 3–4 pickings (manual).
• Avoid wet harvest → prevents staining.
• Average yield:
  • Desi: 10–12 q/ha.
  • Hybrids: 15–20 q/ha.
  • Bt hybrids: 25–35 q/ha (with good management).

16. Post-Harvest Practices

• Ginning: separates lint from seed.
• Lint quality depends on staple length, strength, fineness.
• Staple classes:
  • Short <20 mm.
  • Medium 20–25 mm.
  • Long 25–30 mm.
  • Extra-long >30 mm (G. barbadense).
• Seeds graded after delinting.
• Bales prepared (170 kg each).

17. Economic Importance

• Raw material for textile industry.
• Cottonseed oil: edible & industrial.
• Cottonseed cake: protein-rich cattle feed.
• Linters: used in paper, explosives, cellulose.
• Provides employment to ~60 million people in India.
• Major foreign exchange earner.

18. Important MCQ Facts (Quick Recap)

• Family: Malvaceae.
• Origin: arboreum (India), hirsutum (Central America), barbadense (Peru).
• Seed rate: Varieties 15–20 kg/ha; Hybrids 3–5 kg/ha.
• First hybrid: H-4 (1970).
• First interspecific hybrid: Varalaxmi.
• Delinting chemical: Conc. H₂SO₄.
• Critical irrigations: Germination, flowering, boll formation.
• Major pest: Bollworm.
• Major disease: Bacterial blight.
• India: only country cultivating all 4 cultivated species.