Effect Of Low Temperature And Physiological Age Of Cotton Plant On The Fiber Thickening Development And Fiber Strength

By setting different seeding times, which put the thickening development process of fiber (boll age 25 days to 50 days) in the different temperature conditions, the effects of different temperature at the same physiological age of cotton plant, different physiological age of cotton plant at the same temperature, cooperation of temperature with physiological age of cotton plant on the physiological mechanism of fiber thickening development and fiber strength were studied in a cement pool culture experiment by a cotton variety (America cotton 33B) as experiment material.The main results were as follows:1. Effects of low temperature on physiological mechanism of cotton fiber strength forming process. Mean daily temperature within boll age 25 days to 50 days which was 24.0℃ was the feasible temperature to forming the high-strength fiber, and when mean daily temperature was lower than 21.0℃, it would effected obviously the enzymes activity that related to cotton fiber thickening development, and resulted in the fiber strength falling. When mean daily temperature was 15.0℃ right-and-leftly, the fiber sucrose synthetase activity was evidently fall, and the β-1,3-glucanase activity moved up, the cellulose accumulation quantity and accumulation rate reduced obviously, cotton fiber development was abnormal, boll weight was only 3.22g, and fiber strength was only 15.73CN tex-1.2. Effect of physiological age of cotton plant on the physiological mechanism of fiber thickening development and fiber strength. There were double effect of temperature and physiological age of cotton plant on fiber thickening development and fiber strength, the physiological age of cotton plant was the principal factor and there were evidently effect on fiber thickening development of summer boll for the top fruiting branches and early autumn boll for the lower fruiting branches, boll weight and lint percent and fiber strength in these portion were lower than the others. Low temperature in fiber thickening development process was the principal factor that affected fiber thickening development and fiber strength of late autumn boll, under this testing condition of which the mean daily temperature for late autumn boll was 15.3℃, the fiber sucrose synthetase activity was evidently fall, and the β-1,3-glucanase activity moved up, the cellulose accumulationquantity and accumulation rate reduced obviously, boll weight was smaller than 2.00g and fiber strength was less than 20.0CN tex-1.3. Effect of low temperature cooperated with physiological age of cotton plant on the physiological mechanism of fiber thickening development and fiber strength. At the normal temperature conditions, there were double effect of temperature and physiological age of cotton plant on fiber thickening development and fiber strength. When mean daily temperature within boll age of 25 to 50 days were 26.0℃ (2002) and 26.2℃ (2003), at middle position of cotton plant, the fiber sucrose synthetase activity was highest, and the β-1,3-glucanase activity was lowest, the cellulose accumulation quantity and accumulation rate were higher than which of other temperature and position of cotton plant, fiber orientational indexes of super-molecular was least, so fiber strength was most. At the low temperature conditions, temperature was the most influence factor, and influence of physiological age of cotton plant fell with temperature descending. When mean daily temperature under 16.0℃,the fiber sucrose synthetase activity was evidently fall, and the β-1,3-glucanase activity moved up, so fiber strengths were only 17.08CN tex-1 (2002) and 21.18CN tex-1 (2003), and were independent of influence of physiological age of cotton plant.In conclusion, effects of low temperature and physiological age of cotton plant on soluble protein, endogenesis protect enzyme, sucrose synthetase, β-1,3-glucanase are the major reasons for the differences of the cellulose accumulation quantity and accumulation rate, fiber orientational indexes of super-molecular and fiber strength. The dynamic change laws of sucrose synthetase providing former body (UDPG) for synthesizing cellulose or callose and β-1,3-glucanase synthesizing callose by using UDPG are the vital enzymatic reasons for form of fiber strength.