| Using agricultural meteorological data of cotton growth period during 1983—2012 in Dunhuang, this paper studied the difference of the number of days in each stage of cotton growth, light and temperature condition and their effects on cotton yield, and then built regression equation of yield and growth days, sunshine hours and average temperature. The results show: the planting date mainly affects seeding stage and seedling growth dates; if the sowing dates delay, the two stages will be shorter. The variation of stage days in every developing stage affects the quality and yield of the cotton. The shorter days of squaring stage, the longer the days of wadding stage, which is in favor of the cotton’s growth. In recent 30 years, both daily mean and total sunshine hours have increased, and the climate tendency rate is 0.12 h·10a-1 and 96.14 h·10a-1 separately; the average temperature presents an increasing tendency, and the climate tendency rate is 0.29℃·10a-1. The change of modern climate photothermal conditions is in favor of philotherm cotton. In different growth periods, cotton has different demands on photothermal supply. During the wadding stage the more the sunshine, the higher the temperature, and it will be easier to obtain higher yield. According to the demand of early maturity, disease-resistant cotton varieties on the light and thermal conditions and combining with the local climate, controlling the influence of climatic factors on cotton by scientific regulation are effective ways to harvest high yield of cotton. |