棉纤维发育过程中糖代谢生理特征对氮素的响应及其与纤维比强度形成的关系

 【目的】研究棉纤维发育过程中的糖代谢生理特征对氮素的响应及其与纤维比强度形成的关系，探索改善棉纤维比强度的生理调控技术途径。【方法】以美棉33B（AC-33B）和科棉1号（KC-1）为材料，设置大田氮素水平0 kg N?hm－2（缺氮）、240 kg N?hm－2（适氮）和480 kg N?hm－2（高氮)试验，研究3个氮素水平下棉纤维发育过程中糖代谢的重要物质（蔗糖和β-1,3-葡聚糖）含量变化、调节糖代谢的相关酶（蔗糖酶、蔗糖合成酶、磷酸蔗糖合成酶及β-1,3-葡聚糖酶）活性的动态变化和纤维比强度形成的关系。【结果】两年试验结果表明，在240 kg N?hm－2水平下，棉纤维中的蔗糖酶活性最高，可长时间地为棉纤维发育提供一个充足的物质能量库，蔗糖合成酶、磷酸蔗糖合成酶活性最高，促使纤维发育过程中铃龄5～24 d的蔗糖下降量及24～31 d蔗糖增长量最大，并且全铃期内转化率高且转化彻底，β-1,3-葡聚糖酶活性高，使含量及峰值高的β-1,3-葡聚糖中后期转化彻底，因此，此水平下棉纤维发育过程中蔗糖和β-1,3-葡聚糖含量的上述动态变化，有利于纤维素平缓累积且累积期长，与高强纤维的形成需要的纤维素累积特征相吻合;而在0 kg N?hm－2水平下，棉纤维发育过程的糖代谢生理特征与上述表现刚好相反，最终纤维素累积过快且累积期短，形成低强纤维;480 kg N?hm－2水平则介于上述两者之间。【结论】棉纤维发育过程糖类物质代谢生理特征在0、240、480 kg N?hm－2水平间存在明显差异，该差异是导致纤维最终比强度形成不同的重要因素。在240 kg N?hm－2水平下，上述糖代谢相关酶活性变化及糖类物质供给更为优化，更有利于高强纤维的形成。

Responses of Carbohydrate Metabolism to Nitrogen in Cotton Fiber Development and Its Relationships with Fiber Strength Formation

【Objective】 The aim of the experiment is to study the responses of carbohydrate metabolism to nitrogen application levels in cotton fiber development and its relationships with fiber strength formation. 【Method】 A field experiment was carried out in three nitrogen application levels: N0 (0 kg N?hm-2) as deficient application nitrogen level, N1(240 kgN?hm-2)as optimal nitrogen application level and N2 (480 kgN?hm-2) as high nitrogen application level, and cotton cultivar NuCOTN 33B (AC-33B) and Kemian 1 (KC-1) were used as materials. The study focused on the time course changes of the important matters (sucrose and β-1, 3-glucan) contents and the enzymes (sucrase, sucrose synthetase, sucrose phosphate synthetase and β-1, 3-glucanase, which were key enzymes in carbohydrate metabolism) activities in different nitrogen application levels. 【Result】 The 2-year experiment showed that under the optimal nitrogen application level, the sucrase activity was the highest, which bring abundant energy for carbohydrate metabolism in a long time. Sucrose synthetase and sucrose phosphate synthetase presented the highest activities, which lead to the greater decrease of sucrose content during the 5-24 DPA (Day Post Anthesis) and the greater increment of sucrose content during the 24-31DPA than in the two other nitrogen application levels. The total transformation rate of sucrose in cotton fibers during whole boll age was the highest. The β-1, 3-glucanase activity was the highest that made β-1, 3-glucan transformation rate high. The changes of which mentined above could result in a longer period and more tempered cellulose accumulation process, which was benefit to higher strength fiber formation. While under the deficient nitrogen application level, the carbohydrate metabolism process presented the opposition changes as in the preceding nitrogen application level, and this deteriorated cellulose accumulation led to low strength fiber formation. Lastly, things operated in the high application nitrogen level were between those in the optimal nitrogen application level and in the deficient nitrogen application level. 【Conclusion】 There were notable differences in carbohydrate metabolism among the three nitrogen application levels in cotton fiber development, and these differences were important factors causing the variety in fiber strength development. Under the optimal nitrogen application level, the enzymes activities and the chief matters were preferably accommodated in the fiber development and these could beneficial to high strength fiber formation.