Impact of sowing date on yield and water use efficiency of wheat in different precipitation years in dryland of South Shanxi

Sowing date affects individual development before winter, population quality and yield of wheat. Planting area of wheat in dryland of South Shanxi accounts for 60% total area of the province. The precipitation in the area plays an important role in ensuring agriculture production and food security in Shanxi Province. Under global warming conditions, research on proper sowing date of wheat in Shanxi Province is significant for sustainable development of agriculture. Seven years from 2008 to 2015 were divided into three kinds of precipitation year types-wet precipitation year (2012, 2014 and 2015, precipitation of 527.8-597.2 mm), normal precipitation year (2011, 2013, precipitation of 450.7-483.3 mm) and dry precipitation year (2009, 2010, precipitation of 293.4-385.4 mm), based on the average annual precipitation of Linfen in Shanxi Province in the past 54 years. Precipitation, accumulated temperature, sunshine duration during wheat growth season, as well as wheat growth duration, yield and water use efficiency (WUE) under three sowing dates (Sep. 20, 30 and Oct. 5 in 2008-2009; Sep. 22, 28, and Oct. 4 in 2009-2015) were analyzed to provide a theoretical basis and technological support for high and stable yield production of dryland wheat. The relationship between yield, yield components, WUE and meteorological factors were also analyzed by correlation, multiple regression and path analysis. Results showed that sowing dates significantly affected seedling, tillering and jointing period duration, while no significant effect was observed at booting and maturing stages. There was a significantly positive relationship between wheat growth duration and accumulated temperature. Precipitation year and precipitation distribution in wheat growth season affected wheat yield and yield components significantly. Yield in wet precipitation years were 100.0% and 135.9% higher than those in normal and dry precipitation years, respectively. For different precipitation year types, WUE of grain were wet precipitation year > dry precipitation year > normal precipitation year. WUE of grain were increased with the delay of sowing date in wet and dry precipitation years, but was increased when sowed before Sep. 28 and then decreased in the normal precipitation year. From jointing to heading stage, wheat yield was negatively related with accumulated temperature and sunshine duration, positively related with precipitation. From heading to maturing stage, it positively correlated with accumulated temperature and sunshine duration. There was a positive relationship between yield, yield components and water consumption, but no significant relationship between WUE and meteorological factors and yield components. Annual precipitation and its distribution were the key factors determining high and stable wheat yield in dryland. In wet years, Oct. 4 was a suitable sowing date, which was beneficial for coordinative yield components, high yield and WUE, and low water consumption of wheat. In normal and dry years, Sep. 28 was more suitable for higher yield and WUE of wheat.