Abstract:

Cotton is one of the major economic crops in Anhui Province,which is distributed widely.The area along the Yangtze River is the main production base of high quality cotton in Anhui Province,which is of typical representation in the middle and lower Yangtze River cotton area.It was indicated in the IPCC Fourth Assessment Report that the global land surface temperature increased in the past century.There have been extensive studies on characteristics of climate change in cotton growing season and its effects on cotton yield under global warming.Results showed that the characteristics of climate change in different areas were slightly different.To further understand the characteristic of climate change in cotton growing season and its effect on cotton yield in the area along the Yangtze River in Anhui Province,based on the daily mean temperature,precipitation and sunshine hours data of 12 main cotton production cities and counties along the Yangtze River from 1961 to 2010,the climate change characteristics of mean air temperature,≥10℃ accumulated temperature，precipitation,sunshine hours and their effects on meteorological yield of cotton were analyzed by ordinary least square fitting method and nonparametric MannKendall test.Results showed that in the past 50 years,the mean air temperature and ≥10℃ accumulated temperature of the cotton growing season both increased significantly (P<0.01),with an average increase of 016℃ and 37.13℃·d per decade respectively.The precipitation showed no significant trend (P>005).The sunshine hours reduced significantly (P<0.01) at an average rate of 46.92 h per decade.The mean air temperature of cotton growing season decreased gradually from the 1960’s,and reached the lowest point at 22.7℃ in the 1970s,then it rose from the 1990s and reached the highest point at 23.6℃ in the 2000’s.The ≥10℃ accumulated temperature reached a bottom in the 1970s,then it increased steadily from the 1980’s and peaked in the 2000’s.The precipitation in cotton growing season went up from the 1960’s and reached the highest point at 1 1560 mm in the 1980s,then it fell gradually and reached the lowest point at 920.7 mm in the 2000’s.The maximum sunshine hours appeared in the 1960’s (1 384.1 h),then it became gradually less and bottomed at 1199.2 h in the 2000’s.There was a positive correlation between the meteorological yield of cotton and the mean air temperature of cotton growing season/≥10℃ accumulated temperature,but the relationship, were both not significant (P>0.05).There was a significant negative correlation between meteorological yield of cotton and precipitation in cotton growing season (P<0.01).Each additional 100 mm precipitation would cause a reduction of 29.6 kg/hm2 in cotton yield.However,there was a significant positive correlation between meteorological yield of cotton and sunshine hours in cotton growing season (P<0.01).Each additional 100 h sunshine hours would cause an increase of 39.3 kg/hm2 in cotton yield