| Maize(Zea Mays L.), accounting for30.3%cultivation areas and33.7%total yields of staple foods in China, plays an important role in world food security. The temporal and spatial changes of maize photo-thermal yields in the past few decades are important information needed to evaluate the impacts of global climate change on maize production. The objective of this study is to quantify the temporal and spatial change trends of maize photo-thermal yields and the impacts of temperature and radiation change so as to facilitate evaluating the impacts of climate change on maize production in China. Summer maize planting area in China is almost concentrated in the Huang-Huai-Hai Area of China. In this area, the summer maize have been accounting for34.7%cultivation areas and36.8%total yields of the national maize production ratio, so this study focuses on the research and analysis of summer maize. For this purpose, we firstly collected the experiment data (including development stages and yield) and the daily meteorological data (including solar radiation, minimum temperature and maximum temperature) at agro-meteorological experiment station in this area to calibrate (phenological development parameters and partitioning tables) and validate (yield, and development stages) the GECROS model. The calibrated GECROS was used to simulate summer maize photo-thermal yields with weather data of1961-2007from63sites in the region under study. And then the temporal and spatial change characters of photo-thermal yields and solar radiation, temperature during maize growing season were analyzed with the helping of Geographical Information System (GIS). At last, we further analyzed the effects of solar radiation and temperature changes on summer maize photo-thermal yields in this area. The main research results are as follows:1. Crop model calibration and validation:By calibrating and validating the crop growth model GECROS, provide the basis for model localization, regionalization research. To obtain the suitable parameters for this area, maize (Zea Mays L.) cultivar Zhengdan958, Nongda108and Yandan14were selected for the representatives of summer maize in Huang-Huai-Hai Area of China. The first to use the site observed developmental data (including the date of emergence, flowering date, maturity date) to determine the minimum thermal days for vegetative growth phase (MTDV) and the minimum thermal days for reproductive phase (MTDR), for determining developmental rate parameter value; after debugging through the use of the growth parameters, validate different sites of maize photo-thermal production simulation results. The results validated by recorded flowering and maturing dates showed that the coefficient of determination (R2) are0.91and0.9, the root mean square error (RMSE) between simulated and observed data are1.22d and1.26d. The R2between simulated photo-thermal production and observed yields was0.76. By calibrating the model parameters, GECROS simulated accurately development yields in this area and can be applied to maize production study in this area.2. The temporal and spatial changes of summer maize photo-thermal yield: Identifying the temporal and spatial changes of maize photo-thermal yields in the past few decades can provide important information to mitigate the impacts of climate change on summer maize production and assist in developing future climate adaptation strategies. For this purpose, maize (Zea Mays L.) cultivar Zhengdan958, Nongda108, Yandan14were selected for the representatives of Summer Maize in Huang-Huai-Hai Area of China. The photo-thermal yields during1961-2007were simulated by GECROS with the data weather data from63sites in the region under study. The results show that among different varieties of corn photo-thermal yields trends are presented from southwest to northeast direction increased. Between varieties Zhengdan958highest photo-thermal yields, followed Nongda108and Yanda14min. Zhengdan958’s photo-thermal yields averages ranged from11630to18857kg·hm-2with an average of14301kg-hm-2; Nongda108’s photo-thermal yields averages ranged from10951to16056kg·hm-2with an average of13874kg·hm-2; Yandan14’s photo-thermal yields averages ranged from9242to12730kg·hm-2with an average of11163kg·hm-2. In the47years between1961to2007, Zhengdan958’s photo-thermal yields decadal rate of change varies between-5.7%～0.9%·10a-1with an average of-3.1%·lOa-1; Nongda108’s photo-thermal yields decadal rate of change varies in the range-8.6%～0.6%·10a-1with an average of-3.8%·10a-1; Yandan14’s photo-thermal yields decadal rate of change varies in the range of-6.3%～1.6%·10a-1and the average value was-2.6%·10a-1. In time47different maize varieties for the early years of decline decreased rapidly, medium flat, late and faster. 3. The impacts of photo-thermal changing on summer maize photo-thermal yield: Photo-thermal resources are important climate factors for maize production. Identifying the temporal and spatial changes of photo-thermal resources during maize growing season and its impacts on maize photo-thermal yields can provide important information to mitigate the impacts of climate change on maize production in Huang-Huai-Hai Area of China. For this purpose, based on1961-2007, the effects of temperature increase1℃and solar radiation decrease10%on summer maize photo-thermal yields in China were analyzed by GECROS, as an example of Zhengdan958. The results showed, during1961-2007, the average daily solar radiation change trends during the summer maize growing season varies from-6.7%～-0.4%·10a-1, by averagely-3.3%·10a-1. As the solar radiation decrease10%, the change trends of photo-thermal yields varies from-16.9%to-9.4%, by averagely-12.7%for the summer maize. During1961-2007, the average daily temperature change trends during the summer maize growing season varies from-0.08℃to0.37℃-10a-1, by averagely0.13℃-10a-1. As temperature increase1℃, the change trends of photo-thermal yields varies from-10.3%to-1.3%, by averagely-6.1%for the summer maize. In order to quantify the changes in light and temperature resource potential productivity of maize degree of influence, we refer to the formula: Y=(Tr×Ts)/(Pr×Ps) calculated between1961-2007changes in temperature and solar radiation on corn light and temperature production potential impact ratios. For the summer maize, the solar radiation decrease was the main reason for photo-thermal yields decrease as the temperature and solar radiation change impacts ratio.Combining with the crop model, we analyzed the temporal and spatial changing trends of photo-thermal resources during the summer maize growing season in Huang-Huai-Hai Area in past China and further analyzed the main climatic factors for summer maize production. This work supports strongly to assess the effects of climate change on summer maize production in China and to make measurements to adopt climate change. |
PDF Full Text Request