Scientific use of chemical control technology in cotton can effectively increase yield
Scientific chemical control of cotton is an important scientific measure for increasing cotton yield. Chemical regulation technology has three benefits: first, it helps strong seedlings to develop early, controls height and stabilizes growth, making it easier to give play to the yield-increasing advantage; second, it simplifies cotton field management, saving labor and cost; third, it promotes the transformation of second- and third-grade cotton seedlings, achieving balanced development and increasing yield and efficiency. The principle of chemical control is "small amounts, many times; light control, frequent adjustment." One should master "spray every time, control every time" or "control once at every interval" (flexibly according to soil fertility, rainfall, and growth condition), and it is best to "divide the amount for one application into three applications," ensuring the plant grows steadily and robustly "strong but not excessive" from beginning to end. If chemical control is done poorly, it can cause excessive growth or stiff seedlings that do not develop, affecting the normal growth of cotton. Therefore, in the process of implementing chemical control, the dosage of the chemical control agent must be strictly controlled.
Seed soaking at sowing time. At present, most cotton planting methods use pot sowing. Before sowing, use 1 g of 98% mepiquat chloride (mepiquat, --) mixed with 6 kg to 10 kg of water to prepare a seed soaking solution, place the cotton seeds to be sown into the seed soaking solution, and soak for 10 to 12 hours. The ratio of seeds to soaking solution should preferably be 1:2. The concentration can be lower for delinted seeds and higher for undelinted seeds. After soaking, dry the seeds and then sow. This can promote early and robust development of cotton seedlings and prevent and control underground diseases and pests.
Spraying the top at the seedling stage. About 10 days after the cotton seedlings emerge completely, when they reach one true leaf with one heart or two true leaves with one heart, use 1 g of 98% mepiquat chloride mixed with 80 kg to 100 kg of water and evenly spray it on the tops of the cotton seedlings.
Spraying at the seedling stage. When cotton reaches 8 to 10 leaves and the plant height is 20-30 cm, use 0.5 to 1 g of 98% mepiquat chloride per mu, mixed with 20 kg to 30 kg of water for spraying.
Growth promotion at the bud stage and early flowering stage. When the cotton main stem has 10 to 16 leaves and the plant height is 50-60 cm, upon finding that cotton is flowering, use 2 to 3 g of 98% mepiquat chloride per mu, mixed with 15 kg to 20 kg of water, and evenly spray it on the upper part of the cotton plants. Generally, this can reduce plant height by 5 to 10 cm. This is the best period for shaping an ideal crown structure, delaying row closure, simplifying pruning, and reducing shedding. It can promote deeper root growth, regulate water and fertilizer so the plant grows steadily and robustly, and promote early flowering.
Increasing bolls at the flower and boll stage. About one week after topping cotton at the flower and boll stage, use 4-6 g of 98% mepiquat chloride per mu mixed with 20 kg to 25 kg of water, and spray on the leaves to control the upper fruiting branches from extending long tendrils and to inhibit the growth of superfluous buds, enhance root vitality, increase buds and bolls, and also coordinately prevent premature senescence of cotton, preserve leaves and promote bolls, with significant efficiency and yield increase.
Precautions for chemical control of cotton
1. The amount of mepiquat chloride used is small, so it is best to first prepare a stock solution and then prepare it according to the required concentration, avoiding too much or too little chemical. Its effective period on cotton is about 15 days, so be careful not to interrupt the effective period.
2. The use of mepiquat chloride should be combined with topdressing. Do not reduce fertilization because the leaves become dark green after chemical use. It is best to leave a control row at the edge of the field to observe whether there is a fertilizer deficiency.
3. Timing of chemical control. Mepiquat chloride is prone to oxidative decomposition under strong light, reducing its efficacy, so spraying should be avoided under strong light and high temperature. In summer, it is best to spray in the afternoon after high temperatures and when there is still some light, and pay attention to weather changes. Spraying when field relative humidity is high can maximize efficacy.
4. Cotton leaves absorb mepiquat chloride quickly but export it slowly. Within 2 hours after spraying is the rapid absorption period, during which half of the total applied amount can be absorbed; from 2 to 6 hours it slows down; after 6 hours the effective amount has basically been absorbed. Therefore, generally if it rains within 6 hours after spraying, respraying is needed.
5. The number of applications and dosage of plant growth regulators should be flexibly controlled according to variety, climate, density, cotton plant growth condition, and water and fertilizer conditions.
6. On the basis of implementing chemical regulation, do a good job of hoeing, loosening soil, and pruning.