Effect of different drip irrigation amounts on microclimate and yield of winter wheat

In recent years, drip irrigation technology has been widely used in Xinjiang. This has especially been the case for high-intensity crops like wheat, regarded as a revolution in irrigation technology. Despite this, problems have persisted in the use of drip irrigation technology in field production such as high amounts of irrigation and increased irrigation times. Based on the problems of drip irrigation technology in Xinjiang, field experiments were conducted in Yining County, the northern region of Xinjiang, to identify the effects of different amounts of drip irrigation on the micro-climate and yield of winter wheat, and to provided reference for design of optimal drip irrigation amount of winter wheat. Three amounts of drip irrigation, 3 000 m^-3·hm^-2 (TA), 3 750 m^-3·hm^-2 (TB) and 4 500 m^-3·hm^-2 (TC), were set in a randomized block experimental design. Different indicators were observed under different treatments, including soil temperature, canopy temperature, canopy humidity, atmosphere CO₂ concentration (C_a), soil evaporation, as well as leaf intercellular CO₂ concentration (C_i) leaf, yield and yield components of wheat. The results showed that increasing amount of irrigation remarkably decreased soil temperature at the late growth stage of winter wheat. There were differences in temperature among the treatments, with 1.09 ℃, 1.61 ℃ and 0.52 ℃ differences, respectively, between TA and TB, TA and TC, and TB and TC treatments. With increasing irrigation, canopy temperature of wheat decreased whereas canopy humidity increased. The differences in the highest canopy temperature reached 3.68 ℃ between TA and TC. Both soil evaporation and C_i initially increased and then decreased, while C_a decreased throughout the growth stage with increasing drip irrigation. Yield initially decreased and then increase with increasing irrigation volume. It reached 8 971.66 kg·hm^-2 under TB condition, which was 20.55% higher than that of TA and 6.86% higher than that of TC. Also a significant negative correlation was noted between soil temperature and yield, canopy temperature and yield, and C_i and yield. However, there was a strong positive correlation between canopy humidity and irrigation. It was therefore recommended that 3 750 m^-3·hm^-2 was the appropriate irrigation quantity for winter wheat in northern Xinjiang. This provided theoretical and practical bases for the development of a proper drip irrigation technology in the northern area of Xinjiang.