Abstract:

【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-sensitivity during fiber strength formation.

Key words: cotton')">cotton, temperature-sensitivity, low temperature, fiber development, fiber strength