Effect of daily minimum temperatures on sucrose metabolism of cotton fiber during secondary wall thickening in xinjiang | 新疆棉区日最低气温对棉纤维次生壁加厚期蔗糖代谢的影响

Chinese. 目的研究日均最低气温对棉纤维中蔗糖代谢、纤维素沉积和纤维比强度形成的影响，揭示棉纤维强力变化的机理。方法通过分期播种，使棉铃发育处于不同的低温环境下，研究不同低温水平对新疆棉纤维发育过程中蔗糖代谢中相关物质含量变化、调控蔗糖代谢的关键酶活性变化的影响及与纤维素沉积的关系。结果正常播期条件下，棉株中部棉铃纤维中蔗糖合成酶（SS）和蔗糖磷酸合成酶（SPS）活性高，蔗糖转化彻底，纤维素累积时间长且累积平稳，最终纤维素含量高、纤维强力增加。播期推迟，棉铃发育过程中夜间温度降低，纤维中SPS活性下降、酸性转化酶（AI）和碱性转化酶（NI）活性升高，造成果糖含量明显上升，影响纤维素的沉积。结论棉纤维加厚期＜15.3℃的日均最低气温影响了蔗糖代谢关键酶活性的变化，引起蔗糖转化率下降，果糖循环速率减缓并在纤维中大量富集。

English. Objective It is of great significance to explore the technical approach to reveal underlying mechanisms contributing to cotton fiber strength changes through analyzing the impact of minimum temperature of averages daily on sucrose metabolism, cellulose deposition, and strength formation in Xinjiang.MethodThe impact of different temperatures on the involved substances content in sucrose metabolism during cotton fiber development, and the changes of key enzymes in sucrose metabolism and their correlation with cellulose deposition, were studied through setting different sowing dates. Result Under normal sowing date, the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in the boll fiber in the middle of plant were high. As a result, sucrose converted completely and cellulose accumulated sustainably and steadily. Thus, cellulose content had high and strength increase. Under postponing sowing date, the boll development suffered low temperature at night. The activity of sucrose phosphate synthase decreased, and the activities of acid invertase (AI) and alkaline invertase (NI) increased. Consequently, fructose increased significantly and cellulose deposition was influenced. Conclusion During the cotton fiber thickening period, 15.3℃ of average daily minimum temperature influenced the sucrose metabolism enzyme activities, consequently, conversion efficiency of sucrose decreased. Thus, the circulation rate of fructose was lower and fructose was enriched in fibers.