Effects of Climate Change on Cotton Growth and Development in Shihezi in Recent 40 Years

In order to clarify impact of climate environment on cotton growth and development in Shihezi area，using meteorological data of four meteorological stations in Shihezi area from 1981 to 2018，climate environment and cotton growth and development change characteristics were analyzed and calculated through climate tendency rate，M-K mutation analysis，physiological development time and other methods.Results showed that: from 1981 to 2018，cotton yield and yield per unit area in Shihezi region showed a significant increasing trend，with increasing rates of 14 000 t/a and 57.9 kg/hm2 respectively.Average temperature and minimum temperature in Shihezi region showed a significant increasing trend，with climate tendency rates of 0.32 and 0.51 ℃ /10a respectively，while maximum temperature did not increase significantly at rate of 0.18 ℃/10a.Maximum temperature was more than 35 ℃ per day.The number of high temperature days was the highest in July；the number of days with the lowest temperature <12℃ was mainly distributed in April and September.Frost free period showed a significant increasing trend，climate tendency rate was 6.4 d/10a.Sowing date showed a significant advance trend，advance rate was -0.48 d/a.Cotton physiological development time showed a significant increasing trend，tendency rate was 2.4 d/10a，and mutation year was 1997.