Bud stage is the root center of cotton life, and it is also the key period to build high-yield cotton shed. During this period, the leaves of cotton plants increased, the carbohydrate content in the body increased, the nutrient absorption surface gradually expanded, the carbon assimilation level and nitrogen absorption capacity of cotton plants were strong, and the period of simultaneous vegetative growth and reproductive growth entered. Compared with seedling stage, the nitrogen content of cotton leaves decreased, but it still reached 4.0% ~ 4.5%.

The carbohydrate content gradually increased, and the ratio of carbon to nitrogen rose to about 4.

Therefore, correctly grasping the nutrient supply at this stage is the key to promote the transformation of cotton plants from vegetative growth to vegetative growth and reproductive growth, steadily build high-yield shelves and improve the growth intensity of buds.