Effcets Of Plant Densities On Cotton(Gossypium Hirsutum L.) Dry Matter Accumulation And Distribution, Yield And Fiber Quality

In order to provide scientific basis for optimum plant density, the dry matter accumulation and distribution of cotton after initial flowering under different plant density were studied. Two field experiments with different plant density levels were carried out in Nanjing and Anyang, standing for the ecological conditions in the middle lower reaches of Yangtze River Valley and Yellow River Valley in China, respectively, to study the effects of plant density on plant growth, dry matter accumulation and distribution, yield components, and fibre quality of cotton. The main results were as follows:1Effects of plant density on dry matter accumulation of cottonThe accumulation of dry matter for aboveground plant, stem and branch, and reproductive organ of cotton continuously increased with the progress of plant growth after flowering, the general pattern of crop growth followed a sigmoid function of time. The levels of plant density affected the dynamic accumulation significantly. The dry matter of above-ground, stem and branch and reproductive organ increased as plant density increasing before boll open stage. But after boll open stage, the differents of the high density treatements were not significantly. The dry matter of above-ground, stem and branch and reproductive organ in low density treatments were deficiency.2Effects of plant density on the dry matter distribution of cottonThe dry matter distribution indexes were changed with different plant densities. The dry matter distribution indexes of stem and branch increased as plant density increasing, but the dry matter distribution indexes of leaf decreased. The maximum dry matter distribution indexes of reproductive organ were the plant density of30000plants·hm-2for Nanjing and51000plants·hm-2for Anyang. 3Effects of plant density on yield and fiber quality of cottonThe boll quantity, seed cotton yield and fiber quality with the plant density level of30000plants-hm-2and51000plantshm-2for Nanjing and Anyang, respectively, were more harmonious than that with other treatments. The effects of plant density on the lint percentage were not significantly. According to the method of simulation models, the29370plantshm-2and55600plants·hm-2is the optimal plant density in the middle lower reaches of Yangtze River Valley and Yellow River Valley, respectively.