Climate change and its effect on winter wheat yield in the main winter wheat production areas of China

Climate change plays an important role in crop growth and grain yield. Therefore, there is an urgent need to understand the distribution characteristics and changing trends of climatic factors in the main crop production areas. Furthermore, analyzing the impact of meteorological factors at different crop growth stages is of great significance for maintaining food security and agricultural disaster prevention. In this study, the spatial distribution and variation trends of six critical meteorological factors during the winter wheat growing season in the main winter wheat production areas of China were investigated based on meteorological and phenological data from 69 meteorological and 77 agricultural stations located in the study area. The relationship between winter wheat yield fluctuation and meteorological factors was explored using a multiple regression model. The changing characteristics of meteorological factors in a typical low-yield year was evaluated to identify the key growth stage for winter wheat and the restrictive meteorological factors in the study area. The results showed the following: 1) From 1960 to 2019, the spatial distribution of meteorological factors in the main winter wheat production areas of China was uneven and the variation trends were different. The mean temperature (T_mean), effective precipitation (Pre), and cooling degree days (CDD, the accumulated temperature for daily minimum temperature below 0 ℃) were higher in the southern regions, including Jiangsu Province, Anhui Province, and Henan Province; whereas the sunshine duration (SD), daily temperature range (DTR), and heating degree days (HDD, the accumulated temperature for daily maximum temperature above 30 ℃) were higher in the northern regions, such as Hebei Province, Shandong Province, Beijing, and Tianjin. The T_mean and CDD showed significant increasing trends with average rates of 0.33 ℃∙(10a)⁻¹ and 43.42 ℃∙(10a)⁻¹, respectively; whereas the SD and DTR significantly decreased at rates of 42.30 h∙(10a)⁻¹ and 0.17 ℃∙(10a)⁻¹, and the Pre and HDD trends were spatially heterogenous. 2) The average annual winter wheat yield in different provinces and cities ranged from 3426 kg∙hm⁻² to 5910 kg∙hm⁻² with significantly increasing trends (P < 0.05), but the interannual fluctuation was large in most regions. The determination coefficient for the effect of meteorological factors on winter wheat yield ranged from 0.15 to 0.80, and the winter wheat yield in Shaanxi Province was most affected by climate change (P < 0.05). Over the whole growth period, the ranking of the meteorological factor’s contribution rate to yield was DTR > SD > Pre > CDD > T_mean > HDD. 3) In a typical low-yield year, the key winter wheat growth period was from heading to maturity, and the restrictive meteorological factors during this period were SD, DTR, and Pre. Therefore, future agricultural management and wheat breeding programs must consider the current distribution characteristics and trends of meteorological factors for improving the winter wheat productivity. More importantly, we should pay special attention to restrictive meteorological factors, such as Pre, SD, and DTR, during the critical growing stage of winter wheat from heading to maturity so that it can better cope with meteorological disasters.