Production potential and yield gaps of summer maize in the Beijing-Tianjin-Hebei Region

Crop potential productivity is a key index of scientifically appraising crop production and land population-supporting capacity. This study firstly simulated the potential and water-limited yield of summer maize in the Beijing-Tianjin-Hebei (BTH) region using WOFOST model with meteorological data of 40 years, and then analyzed yield gaps between the actual and potential yield based on statistical data at county level. The potential and water-limited yield of summer maize in the BTH region is 6854-8789 kg/hm(2) and 6434-8741 kg/hm(2), and the weighted average for whole region is 7861 kg/hm(2) and 7185 kg/hm(2), respectively. The simulated yields gradually decrease from northeast to southwest with changes in climatic conditions particularly temperature and precipitation. Annual variation of potential yield is higher in the central and southern parts than the northeastern part. Compared to potential yield, the water-limited yield has higher coefficient of variation (CV), because of precipitation effects. The actual yield of summer maize was 2537-8730 kg/hm(2), regionally averaged at 5582 kg/hm(2), about 70% of the potential yield, implying that the region has room to increase the yield by improving crop management and irrigation systems.