Effects of Different Irrigation Water Volumes with 1,1-Dimethyl-piperidinium Chloride (DPC) on Cotton Growth and Yield

The cotton industry in Xinjiang, China, is limited by irrigation. In cotton production, 1,1-dimethyl-piperidinium chloride (DPC) is used as a growth regulator to improve plant shape, resistance, yield, and quality. However, few studies have investigated the mechanisms by which DPC affects the growth and yield of cotton when combined with different irrigation water volumes. In this study, a split-zone design was used to conduct field experiments over two years using Zhongmiansuo 92 and Zhongmiansuo 087. Three irrigation volumes (3750, 4500, and 5250 m³ hm⁻²; W1, W2, and W3, respectively) and four DPC applications (0, 120, 240, and 480 g hm⁻²) were evaluated. The SPAD (Soil and Plant Analyzer Development) values, photosynthesis, dry matter accumulation and partitioning, agronomic traits, yield, and water use efficiency of cotton leaves were assessed. W2 increased the chlorophyll content and stomatal opening of leaves, improved photosynthetic rates, promoted the accumulation of aboveground dry matter, and increased plant height, main stem node number, and fruit branch platform. The best yields were obtained using W1 and W2 with 120 g hm⁻² DPC and W3 with 240 g hm⁻² DPC. These results can be applied practically to improve cotton production in Xinjiang.