Based on the daily meteorological data of 90 stations for the period 1971 to 2000 and daily 0.25°×0.25° gridded meteorological data under the A1B climate scenario(1951-2070) extracted from the regional climate model RegCM3 released by the National Climate Center,a temperature suitability and coefficient of variation(CV) model for the Huang-Huai-Hai region was built,combing with the growth demand of summer maize for temperature.The spatial and temporal variations of thermal resources,summer maize temperature suitability and its CV in the Huang-Huai-Hai region for the period 1951-2070 were analyzed.The Huang-Huai-Hai area has distinct dry and wet seasons.The heat resources are particularly important for the growth of summer maize.The analysis of this region in this paper,against the background of climate change,is aimed at improving the efficiency of the utilization of climate resources,and providing a scientific basis for summer maize planting.The results showed that:
(1)The accumulated temperature of 10 ℃ with a guaranteed rate of 80% in the Huang-Huai-Hai region showed a gradually increasing trend from north to south,increasing over time.(2)The first day of 10 ℃ with a guaranteed rate of 80% in the Huang-Huai-Hai region showed a gradually increasing trend from north to south,advancing over time.(3)In the stage of seeding to emergence,the temperature suitability showed a trend of rising firstly and then falling,with the CV falling firstly and then rising over time.In the stage of emergence to heading,a falling-rising-falling trend was apparent,with the CV showing a falling-rising-falling-rising trend over time.In the stage of heading to maturity,spatially,the temperature suitability was higher in the south than the north before 2010,but showed a future pattern of being higher in the center than the surroundings.Temporally,it was stable before 2010,but showed a falling followed by rising pattern for the future,which was opposite to the pattern for the CV.(4)The temperature suitability and CV fluctuated in positive phase with time from seeding to maturity.
To date,most research on summer maize suitability has mainly been based on regional climate model data,combined with physiological indexes of existing varieties,which mainly focus on the change in seeding time,growth period,yield,and the effect of crop planting structure by analyzing existing dates.Crucially,there remains a lack of systematic research on the variation of summer maize temperature suitability in the future.Therefore,combining field results with future projections,such as the present work in the Huang-Huai-Hai region,may be the most appropriate research direction moving forwards.This study of the spatiotemporal trends of summer maize temperature suitability and its variation under a future climate scenario in the Huang-Huai-Hai region should help to make full use of climate resources,which may also guide the production of summer maize in the region and provide important information for decision-makers.