Cotton: Challenges and How You Can Overcome them
Why are yields low in Cotton?
Various factors are responsible for low yields in India:
- Low harvest index: Major factor that is responsible for low yields is the low harvest index of the long duration hybrids that are cultivated in India.
- Low ginning out-turn: Indian cotton is characterized by low ginning % (per cent of fiber weight in seed-cotton) of 32-34% as compared to 38-44% in other countries . Hence, the fiber yields are low in Indian cotton.
- Longer duration: To produce large number of bolls, each plant takes longer time of 6 to 8 months. These bolls are formed in a staggered manner in 3 to 5 batches over 160 to 240 days, thereby resulting in 3 or more pickings. Harvesting is labour intensive and expensive leading to incomplete overall picking of cotton.
- Longer reproductive phase: Flowering and fruiting stage extends over 80-160 days for the plants to produce more number of bolls. This increases the risk of failure because of pest and diseases.
- Need for more water and fertilizer: Since more than 80% of water and nutrients are required by the plants during flowering and fruiting phase, the extended reproductive window demands intensive irrigation and fertilizer management for securing higher yields.
How the above challenges can be overcome?
Varieties for increasing productivity
Cultivating short duration (140-160 days) varieties/hybrids which possess sympodial architecture, early maturing with synchronous flowering and fruiting, desirable fiber qualities with high ginning percentage.
Treat delinted seeds with formulation of Trichoderma viride @ 4 gm/ kg of seed or with Carbendazim or Thiram @ 2 gm/ kg seed. Always first treat the seeds with biocontrol agents and then with biofertilizers. Fungicides and biocontrol agents are incompatible. Application of 600 gm/ ha of Azospirillum and 600 gm/ ha of Phosphobacteria or 1200 gm/ha of Azophos and sow immediately.
Plastic mulching or bio-mulching with crop residues, crop rotation with legume crops or green manure crops, intercropping with legume crops such as redgram, black-gram, green-gram, cowpea etc., encourages establishment of predators and parasitoids of sucking pests. Adjusting sowing or planting dates, since early sowing is preferred under most situations. Orienting rows in north-south direction in high density crop for light interception, and row spacing may be kept at 45cm or 60cm or 75cm or 90cm depending on type of variety, soil, water source and weather can enhance productivity of cotton. Gap filling should be done on the 10th day after sowing (DAS). Thinning of seedlings by leaving one healthy plant per hill on the 20th DAS is recommended.
Inter-cultivation and tillage at post-emergence and flowering time, regular crop health monitoring for nutrient deficiencies and for square-shedding, boll shedding etc. to ensure timely interventions of water, fertilizer and plant growth regulator application. Drainage of excessive water is crucial for cultivating a good crop. Wherever irrigation is available, drip irrigation or furrow irrigation may be followed.
Optimizing nutrient application should be based on soil health conditions. Application of fertilizers in three splits at planting, squaring or flowering stage and after topping should be done. Band placement of fertilizers, especially neem-coated urea ensures controlled release with minimum nutrient losses. Application of Farm Yard Manure @ 5 to 10 t/ha or compost after the first rain. Seed treatment with Azotobacter and Phosphate Solubilizing Bacteria @ 25 g each / kg seed is advisable. For cotton hybrids, apply Nitrogen fertilizer in 3 splits namely at basal, 45 and 65 DAS. Foliar application of 2 % DAP + 1 % KCl improves kapas yield.
The crop should be examined periodically for moisture stress, water-logging, diseases and insect pests to initiate timely interventions.
Fields must be kept free of weeds at least for the first 2-3 months of the crop. Stale-weed-bed with pre-emergence herbicides and subsequent inter-culture and weeding should be done to prevent weed competition. Apply Pendimethalin @ 3.3 liters/ha three days after sowing, one hand weeding on 45 DAS is recommended.
Restricting plant height to 80-90 cm, topping when plants have 15 sympodial branches, removal of vegetative branches after square initiation, Removal of 2-3 early fruiting branches of the main stem at peak squaring stage is beneficial to realize higher yields.
Select varieties / hybrids that are resistant to sucking insects, seed treatment to protect seed and seedlings from insect pests, nematodes and pathogens. Short duration varieties under high density planting have less problems from bollworms because of the narrow flowering and boll-formation window, Early sowing helps to escape many insect pests, Avoid insecticides for the first 2-3 months after sowing, Avoid excessive nitrogen to avoid pests and diseases.
Use of light traps and pheromone traps for monitoring of insect pests, use of vegetable oils, botanical pesticides and augmented biological control in the initial phase, Chemical pesticides must be chosen as a last resort. Pesticide and insecticide mixtures must be strictly avoided, Chemical pesticides belonging to WHO Class I (extremely or highly hazardous) must be strictly avoided. As far as possible prefer WHO Class III or safer insecticides. The use of bio-pesticides and biological control must be properly deployed in pest management to ensure least use of chemical pesticides for pest management.
Harvest at frequent intervals at less than 7 days between pickings. It is recommended to harvest up to 11 am when there is moisture so that dry leaves and bracts do not stick to the kapas as this can lower its market value. Separate stained, discolored or insect damaged kapas from the good ones as this also decreases tht market value. Immediately after picking, dry the kapas in shade else the color can change. Do not dry the kapas in direct sun as the fiber can loose strength and luster.