中文摘要：

【目的】研究纤维比强度形成存在温度敏感性差异的2个棉花品种纤维发育生理特性对低温的响应差异。【方法】选用纤维比强度形成存在温度敏感性差异的2个品种（科棉1号：温度弱敏感型品种，苏棉15：温度敏感型品种），通过分期播种，使相同果枝部位棉铃发育处于不同的温度条件，研究低温对棉花纤维发育相关物质含量和酶活性的影响。【结果】正常播期条件下，棉纤维发育期日均最低温为24．0和25．4℃，棉纤维中蔗糖合成酶活性高，β-1，3-葡聚糖酶活性低，蔗糖转化率和纤维素含量均较高，最终纤维比强度最高；晚播所致的低温（棉纤维发育期日均最低温低于21．1℃）则显著影响棉纤维发育，蔗糖转化率、纤维素含量、D-1，3-葡聚糖含量均下降，纤维发育相关酶活性中蔗糖合成酶活性下降、β-1，3-葡聚糖酶活性上升，导致纤维比强度降低。2个纤维比强度形成存在温度敏感性差异的棉花品种纤维发育生理特性对低温的响应存在差异，温度敏感型品种（苏棉15）的蔗糖转化率、纤维素含量及酶活性（蔗糖合成酶、β-1，3-葡聚糖酶）在因播期形成的不同温度间的变化幅度明显大于温度弱敏感型品种（科棉1号）。【结论】低于21．1℃的日均最低温影响棉纤维发育及纤维比强度形成，不同棉花品种纤维发育相关的物质含量、酶活性对低温的响应存在差异，这可能是导致纤维比强度存在温度敏感性差异的主要原因之一。

英文摘要：

[ Objective ] This experiment was carried out to study the physiological mechanisms of variation in temperature-sensitivity of cotton fiber strength formation in different cotton cultivars. [Method] In 2006 and 2007, two cotton cultivars with different temperature-sensitivity during fiber strength formation （Kemian 1 is a temperature-insensitive cultivar and Sumian 15 is a temperature-sensitive cultivar） were used to investigate the matter （sucrose,β-1,3-glucan and cellulose） content and the activity of sucrose synthase and β-1, 3-glucanase which play very important roles in developing cotton fiber. The effects of low temperature on cotton fiber development by setting different sowing dates, thus the fiber development process can be arranged at different temperature conditions. [Result] In normal sowing date, mean daily minimum temperature was 24.0℃ and 25.4℃ during fiber development period, cotton had high-strength fiber, sucrose synthase activity in cotton fiber was the highest, β-1,3-glucanase activity was the lowest, and sucrose transformation rate and cellulose accumulation were the highest. When mean daily minimum temperature was less than 21.1℃ in late sowing dates, enzyme activity and matter content related to cotton fiber development was reduced, sucrose transformation rate,β-1,3-glucan and cellulose accumulation decreased, sucrose synthase activity decreased, and β-1,3-glucanase activity increased, which resulted in lower fiber strength. Two cultivars had different sensitivity to low temperatures, the changing range of Sumian 15 in sucrose transformation, cellulose accumulation and enzyme activity was lager than that of Kemian 1. [ Conclusion ] Mean daily minimum temperature below 21.1℃ which affected cotton fiber development. There were significant differences in the sensitivity of the related enzymes activities and matter content to low temperature between two cultivars, and that may be one of the important factors which lead to the two cotton cultivars had different temperature-s