The Potential Yield And Improvement Of Maize In China Under Climate Change

Maize has been the1st major crop in China, and it is strategically important for the national food security and economic development. Under global warming, the climatic conditions have been changing significantly. Therefore, it is critical to understand the different grades potential yield and the improvement for actual yield of maize to exploit potential yield and ensure national food security. In this thesis, yield was selected as the breakthrough point. Agricultural Production System Simulator (APSIM) was used to simulated the3grades potential yields for maize, including radiation-temperature potential yield, rainfed potential yield, climatic-soil potential yield. The distribution patterns and variations of yield level and stability for the potential yield and actual yield were analyzed and the effects of precipitation, soil and management and technology on yield level and stability were made clear in different regions. Besides, the maximum improvements and improvements of the grain yield and total production under optimal fertilizer-water conditions were assessed. The main conclusions were showed as below:(1) During1961-2010, the sunshine duration in maize growing season had been decreasing, while the heating resourse increased. At the same time, the fluctuation of the sunshine duration, heating resourse and precipitation became larger. For the radiation-temperature potential yield, the very suitable and suitable zones were located in the most of Northeast China, North China, and Northwest China, most of Anhui and Jiangsu provinces in the north of East China, and southwest part of Yunnan province in Southwest China, where the sowing areas of maize covered38.8%and33.9%of the total sowing areas in China, respectively. For the rainfed potential yield, the very suitable and suitable zones were located in the south part of Heilongjiang, east part of Jilin and Liaoning in Northeast China, most of Hunan and Jiangxi, south part of Hubei in Central China, most of Guizhou and Chongqing, south part of Sichuan and north part of Yunnan in Southwest China, and most of East China and South China, where the sowing areas of maize covered11.0%and19.8%of the total sowing areas in China, respectively. For the climatic-soil potential yield, the very suitable and suitable zones were located in the south part of Heilongjiang, east part of Jilin and Liaoning in Northeast China, west part of Inner Mongolia in Northwest China, most of Southwest China, East China, Central China and South China, where the sowing areas of maize covered11.2%and19.2%of the total sowing areas in China, respectively. For the actual yield, the very suitable and suitable zones were located in south part of Heilongjiang and most of Jilin and Liaoning in Northeast China, most of Shandong and north part of Hebei in North China, west part of Inner Mongolia, most of Gansu, north part of Ningxia and north and west parts of Xinjiang in Northwest China, east part of Sichuan, west part of Chongqing, northeast part of Yunnan in Southwest China, east part of Jiangsu in East China, where the sowing areas of maize covered41.1%and28.9%of the total sowing areas in China, respectively. (2) It was that45.8%,9.2%and14.3%of the radiation-temperature potential yields for maize were affected by precipitation, soil and management and technology, respectively, while the coefficients of variation of yield increased by0.24,0.02and0.02. Precipitation is the major factor on the yield level and stability for maize in China. In Northeast China, North China and Northwest China, precipitation is the major factor on the yield level and stability for maize. Meanwhile, the management and technology is the major factor on the yield level and stability for maize in Southwest China, Central China, East China and South China.(3) The maximum improvement of grain yield for maize was9856kg·ha-1, while the total production was23108.8×104t which was2times of the actual production. The highest values were found in Northwest China with the maximum improvement of grain yield was11909kg·ha-1and in Northeast China and North China with the maximum improvements of the total production were9219.0×104t and7134.5×104t, which were2.2and1.8times of the actual production. Under the optimal fertilizer-water conditions, the grain yield could be increased by3777kg·ha-1, while the total production could be increased by8856.9×104t, which was0.8times of the actual production. The highest values were found in Northwest China with4920kg·ha-1increase of grain yield and in Northeast China and North China with3343.1×104t and2755.0×104t increases of total production, which were0.9and0.7times of the actual production.