YIELD RESPONSE OF WINTER WHEAT (TRITICUM AESTIVUM L.) TO WATER STRESS IN NORTHERN CHINA: A META-ANALYSIS

Water deficit is one of the main environmental constraints affecting the yield of winter wheat. We quantified the effect of water stress on the grain yield of winter wheat in northern China, by using meta-analysis method. Database was obtained through 1921 experimental observations derived from 53 research articles of the 2000 to 2017 period. The results showed that the grain yield was significantly affected by the water and latitude. Grain yield and number of spikes (ha(-1)) increased with the total water from 1001 m(3 )ha(-1) to 4000 m(3) ha(-1). However, grain yield and number of spikes did not increase further at higher rates (>4000 m(3) ha(-1) ). The grain yield, number of spikes and thousand grain weight were higher at a total water of 1-1000 m(3) ha(-1) , than those at 1001-2000 m(3) ha(-1) . Water stress had no significant effect on grain number per ear. The grain yield first increased with the latitude to a maximum of 36-37 degrees and then decreased with increasing latitude (>37 degrees). In conclusion, the maximum yield of winter wheat was attained at 36-37 degrees latitude and 3001-4000 m(3) ha(-1) total water.