This study was conducted to determine whether selecting an optimum sowing date could improve yield. The experiment consisted of sowing a film-covered, drip-irrigated cotton field on four sowing dates from April to May in 2011-2012 at the Agrometeorological Experimental Station of Wulanwusu, which was in an arid region of northwestern China. Late sowing dates produced less yield and water-use efficiency than did the normal sowing dates. The yield increased with the increases of mean diurnal

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... rature range (DTR) from full bloom to maturity, mean temperature and sunshine hours (SH) during the whole growing season (WGS), accumulated temperature (AT) and days from squaring to anthesis and mean temperature during the reproductive growth stage. However, the main effect factors of meteorological parameters were AT from squaring to anthesis, mean temperature during the WGS and AT from sowing to emergence. The main effect factors of yield component were boll number per plant, gin turnout and boll weight. Boll number per plant suffered from mean DTR from boll setting to maturity and SH during the WGS. Gin turnout was affected by mean temperature during the WGS and mean DTR from boll setting to maturity. Sowing date, year and their interactions all significantly affected the yield. Sowing date was an important factor affecting the yield and reproductive duration. With climate change, an earlier planting date might be an efficient method of increasing yield.