Response Of Maize Production To Climate Change In Northeast China

Northeast China is the spring maize production base of China. It has important significance for ensuring maize production in Northeast China under climate change. This study was based on the grid meteorological data of 0.5°×0.5°for 1981—2010 in Northeast China, daily meteorological data from 91 meteorological stations, observational data of maize from 60 agricultural meteorological stations, and production data of maize from 202 districts. Methods of trend rate, moving average, spearman correlation analysis, nonlinear test and stability test were used. Climatic variations in Northeast China over the past 30 years were analyzed. Then, responses of maize growth stages, meteorological yield and planting variety to climate change were quantitatively assessed. Finally, response law and influence mechanism of maize production to climate change were explored. The key findings are:(1) In recent 30 years, quantity and allocation of climatic resources had changed significantly in the northeast region. From 1981 to 2010, the annual average temperature increased, the annual total precipitation decreased, while the annual total sunshine hours had no obvious change. In the growing season of spring maize, the temperature increased more obviously and the rainfall decreased more significantly at high latitudes. As for temperature growing season, a continuous increase in thermal resource was found. The low values of precipitation resource were moving towards the southeast. The sunshine resource constantly declined in the central and southeastern regions of Northeast China. Therefore, the suitable planting areas of spring maize were expanded.(2) From 1981 to 2010, all the dates of maize critical growth stages were postponed significantly. Especially, the number of days was increased during the late maize growth stages, and the growth period of maize was extended. Currently, maize varieties were mainly medium-late maturing and late maturing varieties, which replaced early-maturing varieties in succession. The increasing rate of maize yield became slow gradually over the past 30 years, while total maize yield was doubled because of the increase of planting area. The warmer meteorological conditions in the 1990 s had positive effects on the maize meteorological yield. Based on maize growth stages, the average climatic potential productivity was more than 10000kg/hm2 in the southeastern Northeast China. However, in the northwestern Northeast China, the average climatic potential productivity of spring maize was lower.(3) Main meteorological factors that affected maize production had been selected with the method of spearman correlation analysis. The results showed that: temperatures were the main meteorological factors of maize growth stages. By the way, variations of maize growth period were caused by the replacement of varieties to a large extent. The maize meteorological yield was simultaneously restricted by temperature, precipitation and sunshine. Generally, weather conditions at some stages of the maize late growth had the most significant impacts on meteorological yield.(4) The response of maize growth stages was sensitive to the climate change. In the 1990 s, when weather conditions occurring mutation, the maize growth stages occurring mutation followed it. Response rates of maize planting varieties to climate change were faster in the Northeast China. Actually, if we only considered the thermal resource, maize variety maturity could improve one grade to the late-maturing variety in Northeast China over the past 30 years.(5) Response models of maize growth intervals and meteorological yield with their optimal meteorological factors were built by selecting the potential meteorological factors on different time scales. The results showed that: the relationship between maize growth intervals and optimal meteorological factors was linear, and average accuracy rates of regression models were over 92.4%. The relationship between maize meteorological yield and optimal meteorological factors was generally nonlinear. The effects of temperature on meteorological yield were obvious and stable at the east of high latitude regions, while the effects of precipitation and sunshine on meteorological yield were quite prominent at the west of high latitude regions and low latitude regions.