中文摘要：

【目的】研究棉株生理年龄对棉纤维加厚发育及纤维比强度形成的影响．【方法】通过设置播期试验使位于棉株不同部位的棉花“三桃”（伏桃、早秋桃和晚秋桃）的棉纤维加厚发育期（铃龄25～50d）处于相同的温度条件下（统计伏桃、早秋桃和晚秋桃棉纤维加厚发育期日均温分别为22．0、19．4和15．3℃）。【结果】棉花“三桃”的棉纤维加厚发育及纤维比强度受温度和棉株生理年龄的双重影响，棉株生理年龄是影响伏桃、早秋桃棉纤维加厚发育的主要因子，对棉株上部果枝的伏桃和下部果枝的早秋桃棉纤维加厚发育具有显著影响，铃重、衣分和纤维比强度均明显低于其他部位；棉纤维加厚发育期低温则是影响晚秋桃棉纤维加厚发育及纤维比强度的首要因子。在本试验15．3℃的温度条件下，棉纤维蔗糖合成酶活性显著降低，D-1，3-葡聚糖酶活性显著升高，同时纤维素累积量和累积速率均显著降低，棉花铃重低于2g，纤维比强度低于20CN．tex^-1。【结论】棉株生理年龄对伏桃、早秋桃和晚秋桃纤维比强度的影响作用依次增强。

英文摘要：

[Objective] Effects of physiological age of cotton plant on the physiological mechanism of fiber thickening development and fiber strength were studied. [Method] By setting different seeding times, puting the fiber thickening development process of boll which situated in the different positions of cotton plant under the same temperature conditions, mean dally temperature for summer boll, early autumn boll and late autumn boll within boll age of 25 to 50 days were 22.0℃, 19.4℃ and 15.3℃ accordingly. [Result] The results of 2-year experiment showed that： there were double effect of temperature and physiological age of cotton plant on fiber thickening development and fiber strength formation, the physiological age of cotton plant was the principal factor and there were evidently effects 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＂C, the fiber sucrose synthetase activity was evidently fall, and the B-l, 3-glucanase activity moved up, the cellulose accumulation quantity and accumulation rate reduced obviously, boll weight was smaller than 2 g and fiber strength was less than 20 CN-texl. [Conclusion] Effect of the cotton physiological age on the fiber strength enhanced more and more among summer, early autumn and late autumn bolls.