Several Technical Measures to Focus on in July After Cotton Topping
I. Scientific Chemical Regulation
1. Regulation According to Growth Vigour
After cotton topping, generally 1 to 2 chemical regulation applications are made. The first is 3 to 5 days after topping; for fields with about 12,000 plants per 667 sq m, apply 4 to 5 grams of mepiquat chloride in 30 kg of water; for fields with more than 16,000 plants, apply 6 to 7 grams of mepiquat chloride in 40 kg of water. The second chemical regulation depends on the individual development and population size of the cotton plants, and moderate heavy regulation is carried out according to the weather, soil moisture, and the growth vigour and appearance of the cotton plants, generally applying about 8 grams of mepiquat chloride per 667 sq m. Through the action of mepiquat chloride, the goal is ultimately to effectively control ineffective flower buds and the growing tips of empty fruit branches, realize the transformation from vegetative growth to reproductive growth, shape a growth vigour and appearance of balanced yield increase, and ensure an increase in the number of bolls set at the top of the cotton plants and in single boll weight, creating conditions for high yield.
2. Proper Spraying Method
The correct method for spraying mepiquat chloride is: first dissolve the mepiquat chloride in a weighed basin or plastic bucket container, stir thoroughly, and add it to the sprayer according to the mepiquat chloride content per 100 grams of mepiquat chloride aqueous solution.
When spraying mepiquat chloride, the principles should be followed of even but not full, spray the tall and not the short, and spray the vigorous and not the weak, and it is best to do so after 5 p.m. Spraying under high temperature and strong light will reduce the effect; encountering rain within 6 hours after spraying will affect the absorption effect; if the rainfall is heavy and lasts a long time, it will be ineffective and re-spraying is needed.
II. Irrigation According to Local Conditions
After cotton topping, the plants enter the peak period of reproductive growth, and flowers, buds, and bolls gradually form. This stage is the period of greatest water demand in the entire growth period of cotton. For cotton fields with conventional furrow irrigation, the first watering should be little, the second watering should be sufficient, and the third and fourth waterings should be ample (the third and fourth waterings are the second watering after topping). Watering must stop before August 15 to prevent the cotton plants from remaining green and late-maturing.
III. Fertilizer Supplementation According to Appearance
After topping, cotton needs more water and fertilizer. For cotton fields with conventional irrigation, different amounts of nitrogen, phosphorus, and potassium fertilizers are applied at the time of base fertilizer and the first and second waterings. After topping, nitrogen fertilizer should be supplemented according to the branch and leaf appearance of the cotton plants, applying 5 to 8 kg per 667 sq m. At the same time, increase the spraying of foliar boron fertilizer; dissolve 50 grams of Sulubor in 50 kg of water per 667 sq m and spray, for a total of 2 sprays, to increase the boll-setting rate.
IV. Timely Harvesting
After boll opening, cotton picking should adhere to the "three whites," and carry out graded picking, graded stacking and sun-drying, and graded selling, to ensure cotton quality and quantity and a bumper harvest.