Effects And Adjustable Mechanism Of Potassium Nutrient On Boll And Fiber Development Of Different Part Cotton In The Plant Of High Quality Cotton

The study was undertaken on two cultivars of high quality upland cotton, one was hybrid cultivar Kemian No.3, and another was conventional cultivar Kemian No.4, during the 2004 and 2005 growing seasons at the the Jiangsu Provincial Key Laboratory of Crops Genetics and physiology, Yangzhou University, Yangzhou, China. The object of this study was to investigate the effects and adjustable mechanism of potassium nutrient on boll and fiber development of different part in the plant of high quality upland cotton. The main results were as follows:1,The increase of potassium fertilizer application and reasonable potassium fertilizer management with the ratio of basal dressing to fertilizer application during flowering to boll development was 5:5(Kemian No.3) and 7:3 (Kemian No.4) were helpful to boost the boll development, increased boll size, enhanced boll weight and the lint yield. The results in this study showed that, KCl fertilization application from 0 to 25kg per 666.7m2 increased the boll volume and the boll weight in the middle and upper parts of the plant, especially for those bolls at upper part of the plant, the increased extent of the boll size and boll weight were higher. Compared to the control (no potassium fertilizer application), the boll volume at the upper parts of the plant increased 14.28% and 21.79% at 38 days after anthesis for cultivar Kemian No.3 and Kemian No.4 respectively, and the boll weight enhanced 21.06% and 23.6% for cultivar Kemian No.3 and Kemian No.4 respectively, when KCl application was at 25kg per 666.67m2. The potassium fertilizer management with the ratio of basal dressing to fertilizer application at flowering to boll development was 5:5(Kemian No.3) and 7:3 (Kemian No.4) were more beneficial to the increase of the boll volume and boll weight at the middle part and upper part of the plant. In addition, increased potassium fertilizer application and reasonable potassium fertilizer management with the ratio of basal dressing to fertilizer application at flowering to boll development narrowed the difference of the boll volume and boll weight between the middle part and upper part of the plant, which enhanced the boll weight of the whole plant and increased lint yield. The difference between the middle part and the upper part of the plant was 1.25cm3 for the boll volume and 0.3975g for the boll weight, when KCL application at 25kg per 666.7m2; the difference was 4.05 cm3 for the boll volume and 0.6195g for the boll weight with no potassium fertilizer application.2, The increase of potassium fertilizer application and reasonable potassium fertilizer management with the ratio of basal dressing to fertilizer application at flowering to boll development was 5:5(Kemian No.3) and 7:3 (Kemian No.4) were helpful to improve the fiber quality of the whole plant. The results in this study showed that the fiber length and the maturity increased at the middle part and the upper part of the plants with KCl application at 15kg and 25kg per 666.7m2, the difference of the fiber quality characters reduced between the middle part and the upper part of the plant. when KCl application at 25kg per 666.7m2, the difference for the fiber length was only 0.6 mm between the middle part and the upper part of the plant, for the fiber maturity was only 0.05. When potassium fertilizer management with the ratio of basal dressing to fertilizer application during flowering to boll development was 5:5(Kemian No.3) and 7:3 (Kemian No.4) (KCl application at 25kg per 666.7m2), the fiber length, the strength, the micronaire and the maturity increased at the middle part and upper part of the plant, and the difference narrowed for these fiber quality characters between the middle part and the upper part of the plant, which improved the fiber quality of the whole plant. These results suggested that increased potassium fertilizer application and reasonable potassium fertilizer management can obtain the goal of both high yield and good fiber quality at the same time for the high quality cotton.3, The physiological mechanism of increasing potassium fertilizer application and reasonable potassium fertilizer management enhanced the boll weight and improved fiber quality was as follows: the nitrogenous matter contents increased in root exudates, chlorophyll content enhanced in the functional leaf of the plant and fruiting-branch leaves, the soluble sugar, sucrose and starch contents boosted in the leaf of the middle and upper part of the plant, the soluble sugar and sucrose content increased in the phloem of boll petiole. The soluble sugar, sucrose and starch content decreased in the boll shell, the ATP enzyme activity enhanced in the fiber, and the difference of these physiological indexes reduced between the middle part and the upper part of the plant. In addition, the IAA and ZR contents increased in the boll shell and the fiber, especially for boll shell and fiber at the upper part of the plant. there were significant positive correlation between the IAA, ZR content of the boll shell at 10 days after anthesis and the boll volume(r=0.9777**,r=0.8986**), there were also significant positive correlation between IAA content of fiber at 20 days after anthesis and the fiber length (r=0.8407*), ZR content of fiber at 10 days after anthesis and the fiber maturity respectively (r=0.8431**). These results suggest that potassium nutrient induced the endogenous hormonal system of the boll, which enhanced boll development,bolstered boll weight and improved fiber quality of the whole plant for the high quality upland cotton.