Prevention of premature senescence of cotton in the later stage

Premature senescence of cotton plant means that when the growth center turns to reproductive organs after the cotton plant enters the flower and boll stage, if the cotton plant is malnourished and the bud and boll compete with the vegetative organs for the organic nutrients produced by leaves, the vegetative growth will be more restrained. After this kind of cotton plant bears several cotton bolls in the middle and lower part, the upper part of the cotton plant appears the phenomenon of vegetative growth decline, such as top tip, hard hair, red stem to the top, thin and yellow leaves, which is the premature senescence of cotton plant.

Premature senile cotton plants generally appear in cotton fields where the soil is stiff, the fertility is poor, the root system is poor, and the root group is small; or the amount of fertilizer applied during the flower-and-boll period is insufficient, and the roots can not grow normally due to summer drought after fertilization; or cotton fields with low-lying terrain and poor drainage hinder root growth; early-onset cotton is also prone to premature senility if field management measures fail to keep up. In addition, cotton plants in cotton fields with severe Verticillium wilt and potassium deficiency in soil will also senescence prematurely. Comprehensive measures should be taken to prevent premature senescence of cotton.

1. Strengthen the management of fertilizer and water. The lack of fertilizer and water is the main cause of premature senescence of cotton. It is necessary to re-apply flower and boll fertilizer according to seedling condition, climate and soil condition, such as covering top fertilizer if flower and boll fertilizer is insufficient. In case of drought, we should fight drought in time, promote fertilizer with water, and ensure that the fertilizer effect is brought into full play in a timely manner. If the premature senescence of cotton is caused by the lack of potassium in the soil, the potassium fertilizer should be applied at the same time as the basal fertilizer and at the seedling stage. Apply potash fertilizer (potassium sulfate or potassium chloride) 5 kilograms per mu according to different places.

2. Prolong the functional period of leaves. The functional period of normal leaves is generally about 8 weeks, but due to the influence of pests such as cotton bollworm, blind Toona sinensis, red spiders and diseases such as Verticillium wilt and red leaf stem blight, the leaves are damaged or shedding, reducing the function of leaves and accelerating premature senescence. Therefore, it is necessary to control insect pests, reduce diseases and prolong leaf function.

3. Promote root growth. The root is the main organ of absorbing fertilizer and water, and the weakening of root system is the direct cause of the aboveground premature senescence of cotton plant. Therefore, the bud stage should do a good job of deep ploughing, ditching, soil cultivation, deep fertilization to promote root. Deep and developed roots absorb a wide range of water and fertilizer, have strong resistance to stress, and can effectively prevent premature senility. In the later stage, such as Rain Water, the cotton field should be drained in time to prevent water stains and delay the decline of root function.

4. hit the top at the right time. Fine pruning, removal of ineffective buds, buds after the Beginning of Autumn or flowers after White Dew should all be removed to reduce consumption.

5. Foliar spraying fertilizer. The nutrient absorption function of cotton root system decreased obviously from late August to late September, when five kinds of fertilizers such as nitrogen, phosphorus, potassium, zinc and boron were sprayed on cotton leaves. It can prevent premature senescence, promote precocious maturity, prevent disease, prevent boll falling and bear big peach, and has a significant effect on increasing yield and income.