Effect of plant growth regulator compounding on growth and endogenous hormones in cotton

In order to investigate the effects of different combinations of plant growth regulators on the growth and development of cotton, Zhongmiansuo 117 was used as the test variety, and mepiquat was used to combine with low, medium, and high concentrations of diethyl aminoethyl hexanoate, 24- epibrassinolide and prohexadione calcium in a randomized block group trial, and three sprays were carried out from the early to the full bloom stage of cotton to analyze the effects of the spraying on cotton agronomic traits, dry matter accumulation, yield, and quality and other indexes. The results showed that: mepiquat 98% SP 45 g/hm² + diethyl aminoethyl hexanoate 5% SL 120 mL/hm² and mepiquat 98% SP 45 g/hm² + prohexadione calcium 10% SC 450 mL/hm² showed a good effect on stemming control, increased the number of fruiting shoots and the diameter of the main stems, and promoted the bolling of cotton plants. The combination of mepiquat 98% SP 45 g/hm² + diethyl aminoethyl hexanoate 5% SL 120 mL/hm² significantly increased the seed cotton yield, the number of bolls per hectare and the weight of single bolls, and also improved the degree of neatness to a certain extent; the endogenous GA₃ increased, and the IAA and ABA decreased, which helped to increase the quality of the yield in the actual production. The combination of mepiquat 98% SP 45 g/hm² + prohexadione calcium 10% SC 450 mL/hm² significantly increased the amount of aboveground dry matter accumulation and dry matter distribution ratio of reproductive organs. It also regulated the increase of endogenous ABA and effectively promoted nutrient transfer to reproductive organs. The study showed that the combination of mepiquat 98% SP 45 g/hm² + diethyl aminoethyl hexanoate 5% SL 120 mL/hm² and mepiquat 98% SP 45 g/hm² + prohexadione calcium 10% SC 450 mL/hm² could realize the trait control and yield increase through the endogenous hormone regulation, which is of practical application in production.