Evaluation Of Climate Resources And Heat Resource Use Of Spring Maize In Eastern Inner Mongolia

Natural endowments have a strong influence on agricultural production,which is unchangeable.As the factor impacting crop developments,heat resource is an important factor in determining agricultural structure and cropping systems,the abundance,spatial and temporal patterns are directly influenced by climate change.Therefore,it is important to analyze the spatial and temporal characteristics of heat resource,to identify the trends of climate productivity potential,to evaluate the use of heat resource and propose adaptation measures for efficient use of resources.Four eastern Inner Mongolia city(leagues)(Chifeng,Tongliao,Hinggan and Hulunbuir)were taken as examples,M-K test and Arc GIS spatial interpolation were used to analyze the spatial and temporal characteristics of heat resource over the past 50 years(1973—2020)based on daily data from meteorological stations in and around the study area,using temperature ?10°C as a proxy.Trends in temperature,precipitation productivity potential,and climate productivity potential were evaluated using Miami model and Thornthwaite Memorial model,respectively.Based on the information of spring maize phenological stages extracted from MODIS data in 2018-2019,combined with the actual planting situation of large agricultural households at joint experimental sites,the beginning and end dates of temperature ?10? and maize phenological stages were used to calculate the distribution and proportion of heat resource at each stage to evaluate the matching of maize growth with actual heat resource and its impact on yield.The CERES-Maize module of DSSAT is used to simulate resource use efficiency measures by adjusting sowing dates.In this study,the spatial and temporal variation characteristics of heat resource based on daily data from meteorological stations were evaluated,using temperature ?10°C.The results showed that heat resource in eastern Inner Mongolia increased significantly from 1973 to 2020,with abrupt changes in the period from the 1990 s to the beginning of 21 st century.Due to the spatial differences of latitudinal and altitude,heat distribution patterns showed an increase from the northwest to the southeast,and there was a clear latitudinal zonality of accumulated temperature in heat rich areas at low latitudes,but increased at high latitudes along both sides of the Great Khingan.The change characteristics of climate productivity potential based on Miami model were consistent with those of accumulated temperature,with an overall increasing trend,while the precipitation productivity potential fluctuated greatly in the last50 years and had a clear change trend.Climate productivity potential,based on Thornthwaite Memorial model which combined temperature and precipitation factors,showed no obvious overall change trend,with a large fluctuation at the beginning of 21 st century and an increasing trend in the last decade.Based on the key maize phenological stages extracted from remote sensing images and the beginning and end dates of temperature ?10?,the heat remaining after maize maturity was calculated and the heat resource use was evaluated.The results showed that the time difference was within 15 days between spring maize maturity and the end dates of ?10? at the joint experimental sites in the four leagues of eastern Inner Mongolia,and the heat resource remained for kernel dehydration in mechanical harvesting ranged from 0 to 200?·d,as would satisfy heat demand for kernel dehydration on standing stalks,but did not provide a sufficient heat guarantee;however,there was heat resource remained before maize sowing unused by crops.Therefore,there was wastes of resources before maize sowing,which made the overall growth process of maize lagged behind,with an accelerated nutritional growth rate and an ultimately yield decrease.Using DSSAT,based on the data from large agricultural households at joint experiments in 2018 in Kailu County,Tongliao City,to simulate resource use efficiency measures by adjusting the sowing dates.The results showed that the advancement of the spring maize sowing date could lead to an earlier tasseling stage and contribute to higher yields,and that 3-7 days earlier was beneficial to yield,ranging from-2.69% to 7%.