Optimizing cotton plant architecture and yield through the use of plant growth regulators

Abstract

Growth regulation in cotton (Gossypium hirsutum L.) is essential for shaping optimal plant architecture and achieving full mechanization in its cultivation. However, the regulators are often poorly controlled when applied individually, leaving plants with poor morphology, which in turn leads to lower yields. Combining regulators is the key to solving these problems. In this study, the effects of spraying 0.1% thidiazuron (TDZ) (T1) individually and TDZ mixtures with 98% mepiquat chloride (T2), 5% prohexadione calcium (T3), and 5% uniconazole (T4), with pure water as a control, were studied. The results showed that the combination of plant growth regulators optimized the cotton plant architecture, and the leaf area index, diffuse not-intercepted area, as well as mean tilt angle of the T4 group increased by 58.4%, 28.1%, and 9.9%, respectively, at the boll-setting period. Net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and transpiration rate increased by 27.2%, 20.0%, 6.6%, and 52.4%, respectively, at the peak flowering period. Further, the dry matter accumulation of cotton in reproductive organs increased by 9.6% and 14.3% for 2 years, respectively, and the average seed cotton yield of 2 years was significantly increased by 12.5% under this treatment condition. This study revealed that the combination of 0.1% TDZ and 5% uniconazole could improve the photosynthetic capacity of cotton plants and increase dry matter accumulation through optimizing plant architecture, thus increasing the seed cotton yield. In conclusion, it provides technical guidance for suitable plant architecture and high-yield cotton cultivation in Xinjiang.