中文摘要：

选择纤维比强度差异明显的3类基因型4个棉花品种，研究季节桃纤维发育相关酶活性的动态变化及其与纤维比强度形成的关系。结果表明，棉花伏前桃、伏桃、早秋桃和晚秋桃纤维POD、IAAO活性的动态变化依次下降，蔗糖合成酶、8—1，3-葡聚糖酶活性与之相反。对于伏前桃和伏桃，纤维发育相关酶活性高，有利于纤维素累积特性的优化和高强纤维的形成；早秋桃纤维发育关键酶活性高于伏前桃，且纤维素累积特征较优，最终纤维强度较伏前桃高；随着日均温降到20℃以下，棉株的衰老，晚秋桃纤维发育相关酶活性峰值后移，纤维比强度增长幅度大幅降低。棉花季节桃纤维发育过程中相关酶活性动态变化的差异是导致纤维素的累积特性及纤维比强度差异形成的重要生理原因之一。

英文摘要：

By choosing four cuttivars with significant difference in fiber strength as materials, we stud- ied the relationship between fiber strength and activity of enzymes associated with cotton fiber devel opment in cotton seasonal boll （pre-summer boll, summer boll, early autumn boll and later autumn boll）. The results showed that the activities of POD and IAA oxidase promoted with anthesis date postponing, while the activities of sucrose synthetase and β-1,3-glucanase declined. In PSB （pre-summet boll） and SB （summer boll） fiber, the higher activities of related enzyme they had, the better characteristic cellulose deposition and the higher strength fiber they got. The EAB （early autumn boll） had higher activities of key enzymes and better cellulose deposition characteristic than PSB, and EAB had higher fiber strength than PSB in the end. In LAB （later autumn boll） fiber, the activity peaks of related enzymes delayed with the temperature got lower than 20 ℃ and cotton plant was se nescing, and these resulted in lower strength fiber formation. Cotton seasonal bolls had differences in enzyme activities and cellulose deposition. And these physiological differences might be one important reason for different fiber strength formation in cotton seasonal bolls.