The budbell shedding of cotton is a common phenomenon in production, and as the main symptom of premature aging and a yield limiting factor, it has also received general attention from experts and scholars at home and abroad. In the production of cotton, the bud bell shedding will generally reach 60% to 70%, and the severity can reach more than 80%. There are many factors affecting the shedding of cotton buds, and the reasons for them can be better controlled to reduce the shedding rate, improve the ringing rate, and achieve high cotton yield and high efficiency.
1 Causes of cotton bud bells falling off
1.1 Cotton varieties
Depending on the variety of cotton, the degree of budbell shedding varies. Pests such as cotton bollworms and cotton blind bugs like to lay eggs on hairy cotton varieties, and smooth leaf varieties are 40.3% less affected than bud bells of multi-furry varieties.
1.2 Physiological factors
The bell shedding caused by physiological factors accounts for about 70% of the total number of cotton bell shedding, and the factors related to physiological shedding are mainly light, temperature, water, nutrients, hormones and insemination in the body.
Cotton is a warm-loving crop, but high temperature heat damage is an important cause of budbell shedding. The high temperature in the reproductive stage leads to the development of male and female gametes in cotton is hindered, inhibiting pollen grain germination and the growth of pollen tubes within the stigma. The average daily temperature of cotton flowering period is above 32 °C, which can lead to reduced vitality of pollen grains, no cracking of anthers, decreased photosynthesis, enhanced respiration, and caused serious shedding of budbells, and extreme heat of ≥ 35 °C will cause obvious heat damage to cotton.
When there is insufficient light, especially in shaded cotton fields, the synthesis of assimilates and the output of photosynthetic products are reduced, and their transport speed is reduced, which limits the supply of bud bell nutrients, resulting in a large amount of shedding.
Too much or too little moisture can cause the cotton budbell to fall off and worsen, and when the soil moisture is too low, the cotton cannot absorb enough water. Inhibiting transpiration hinders normal photosynthesis, which not only affects the number of fruiting branches, but also causes young buds to lose water and shrink and fall off; if the soil moisture is too much, the soil ventilation is poor, and the root respiration is weakened, resulting in nutrient imbalance in the cotton plant and causing the budbell to fall off.
Nutrients include both organic and inorganic nutrients, of which inorganic nutrients include a large number of elements and trace elements. The unreasonable application of nutrients will also lead to aggravation of cotton bud shedding; insufficient nutrients, causing cotton plant stunted growth and leading to shedding; excessive nutrient content, resulting in excessive plant nutrient growth, group depression, insufficient light, nutritional imbalance in the body, resulting in budbell shedding.
After the content of absorcisic acid, ethylene, auxin and other hormones in the body of the cotton plant is changed, it will cause the hormones to lose their balance and cause the bud bell to fall off.
Unfertilized young bells will eventually fall off. Spraying potion in the corolla during flowering, or in the control of diseases and insects, the formation of auxin in the ovules is blocked, affecting fertilization, and eventually increasing the shedding of young bells.
1.3 Pests and diseases
Cotton blight, verticillium wilt, red leaf stem blight and other diseases that harm cotton leaves and cotton bells can cause bud bells to fall off. The harm of pests such as cotton bollworm, red bollworm, cotton blind bug, cotton red spider, twill moth and other pests to cotton affects the normal growth of cotton plants, or directly harms flowers, buds and bells, causing a large number of bud bells to fall off.
1.4 Other Factors
In the process of farming, people, livestock, and agricultural machinery will cause direct damage to cotton; natural disasters such as winds, heavy rains, floods, etc. will also cause damage to cotton; these can cause a large number of lard bells to fall off.
2 Control measures for cotton bud bell shedding
2.1 Select the appropriate variety
Choose cotton varieties that are resistant to diseases and insects, have strong bell binding and good yield, and try not to plant varieties with many furry leaves.
2.2 Reasonable planting density
According to the fertility of the soil in the cotton field and the plant type characteristics of the cotton variety, the suitable planting density of cotton is reasonably determined. By establishing a reasonable group structure, the field ventilation and light transmission conditions are improved, the utilization rate of light energy is improved, and the bud bell shedding is reduced.
2.3 Water and fertilizer regulation
Coordinating the relationship between vegetative growth and reproductive growth through fertilization and water management can effectively reduce cotton bud shedding. In terms of fertilization: one is to apply sufficient base fertilizer, with organic fertilizer and inorganic fertilizer, inorganic fertilizer is mainly phosphorus and potassium fertilizer, and nitrogen is applied in an appropriate amount; second, less application at the budding stage of topdressing and more application at the bell stage; third, the decline of root absorption capacity at the spitting stage, and timely application of foliar fertilizer. Timely irrigation is made during the peak of the cotton bell to ensure the development of the bud bell's demand for fertilizer water.
2.4 Scientific whole branches
Scientific management of cotton fields, fine whole branches to top, smear extra buds, pluck the top heart, beat old leaves, improve the ventilation and light transmission conditions in the field, prevent the cotton field from closing, promote the development of cotton plants, and reduce the shedding of bud bells. After the topping, a certain concentration of auxin was applied to increase the biomass of the cotton plant, while the number of empty fruit branches and the shedding rate of bud bells in the cotton plant were significantly reduced.
2.5 Chemical regulation
The use of chemical agents or exogenous hormones to promote or inhibit the growth of cotton plants, thereby achieving a reduction in shedding rate. Gibberellin as a drug to prevent premature aging of cotton has been applied to production, spraying during the blooming period can increase the total number of cotton fruit nodes, reduce bud bell shedding, improve the ringing rate and yield. The use of codification and prosotropin can enhance photosynthesis, promote nutrient delivery to bud bells, and help increase the number of ringers and reduce shedding.
2.6 Pest control
Grasp the occurrence of cotton diseases and insect pests, and do a good job in the prevention and control of diseases and insect pests to ensure the healthy development of bud bells and reduce the shedding caused by diseases and insect pests. In the prevention of disease, it is necessary to use fungicides for prevention and control in the early stage of disease; in insect prevention, it is necessary to protect natural enemies to improve pest control and improve the effect of insect control.
2.7 Other Measures
Crop rotation can reduce the residue of germs in the soil, promote the normal growth of cotton plants, and reduce bud shedding. Cultivating soil can improve the ecological environment of cotton fields, increase soil permeability, promote robust root growth, and reduce bud shedding. In field management, human mechanical damage should be avoided as much as possible, and small machines should be used as much as possible when operating. In addition, spraying a bell protector can also effectively reduce the shedding of cotton buds.
Cotton bud bell shedding factors and prevention and control measures
Author: Yao Yanyan (Xihua County Plant Protection Station, Henan Province), Graphic Editor: Tianshan Plant Protection, please indicate the source when reprinting!