Study On The Temporal And Spatial Distribution Trend Of Corn Yield And Water Requirement In Heilongjiang Province Under Climate Chang

China’s main maize production area is Heilongjiang Province.Under the mutual influence of agricultural water consumption and climate change,China’s grain production security is faced with great challenges.It is of great significance to clarify the impact of future climate change on maize yield and Crop Evapotranspiration(ET_c)、Actual Crop Evapotranspiration(ET_a)in Heilongjiang Province and put forward reasonable corresponding measures for efficient use of agricultural water and guarantee food security.Based on two Concentration representative paths(RCP4.5 and RCP8.5)and four Global climate models(GCMs),this study collected the daily meteorological data of 26 meteorological stations in the research area of Heilongjiang Province during the maize growing period.The Aqua Crop model was used to simulate three future periods:2021-2040(2030s),2041-2060(2050s)and 2061-2080(2070s),with maize yield and ET_cunder full irrigation schedule.The effect of climate change on maize yield in Heilongjiang Province was expounded.The optimal irrigation schedule of Heilongjiang Province was selected based on the comprehensive influence of quantity and ET_c.The main conclusions are as follows:(1)There are many differences in the meteorological data of different time and space under the two RCPs scenarios in Heilongjiang Province from 2021-2080.In RCP4.5 scenario,the lowest precipitation during the maize growth period was in 2050s,and the precipitation in the study area was mostly concentrated in the central region;The solar radiation gradually decreased from the east to the west,and the solar radiation in 2050s were higher than that in 2030 and 2070s;The minimum temperature is generally rising during sixty years,and the high value area of the minimum temperature is mainly distributed in Baoqing area;The maximum temperature during the growth period of maize was in the 2070s,and the lowest value was in the 2030s.In the RCP8.5scenario,the precipitation during the growth period of maize will gradually increase from 2021 to 2080,and the middle of the study area is the area with high precipitation;The solar radiation gradually decreased from west to east in space,and the solar radiation in 2030s was the lowest,18.73MJ/m~2;The minimum temperature will generally increase during sixty years.The low value area of the minimum temperature in the study area mainly occurs in the southern region.The minimum temperature in RCP8.5 is higher than the minimum temperature in RCP4.5;The average lowest value of the highest temperature in the three study periods is concentrated in the 2030’s(25.12℃),and the high value area of the highest temperature in space is distributed in the western region.(2)Under the RCP4.5 scenario,the overall trend of maize ET_cin Heilongjiang Province is upward,with the highest average ET_cvalue of maize distributed in the mid-1970s(493.47mm)between 2021-2080,while the highest ET_cvalue in the entire study area is spatially distributed in the southwest region.Under the RCP8.5 scenario,the average ET_cvalue in the 2030’s was 480.50 mm,and the ET_cchanges in the 2050’s and the 2070s were 1.02%and 1.04%higher than those in the 2030’s.The ET_cunder RCP8.5 scenario is generally higher than that under RCP4.5 scenario,and the spatial distribution of ET_cin the two RCPs is consistent.(3)During the 2021-2080,the maize yield which in Heilongjiang Province is gradually increasing with time.Under the two RCPs,the average maize yield in the1970s was 14328 kg/ha and 15038 kg/ha,respectively.The low maize yield areas in the entire study area are mainly distributed in the southeast region.The maize yield under the RCP8.5 scenario is generally higher than that under the RCP4.5 scenario,with maize yield increments of 0.6%,2.0%,and 5.0%in the 2030,2050,and 1970s,respectively.(4)Under the RCP4.5 scenario,the water use efficiency(WUE)of maize in Heilongjiang Province is gradually increasing,with the average WUE of maize from the2030’s to the 2070’s being 2.85kg/m~3,2.87kg/m~3,and 2.91kg/m~3,respectively.The high value region of WUE in space is distributed in the southeast region.Under the RCP8.5scenario,the average WUE in the 1970s was 3.02kg/m~3.Compared to the 1970s,the ET_cin the 1930s and 2050 decreased by 5.3%and 3.2%,respectively.The WUE under the RCP8.5 scenario is generally higher than that under the RCP4.5 scenario,and the spatial distribution of WUE in the two RCPs is consistent.(5)In the RCP4.5 and RCP8.5 scenarios under the three irrigation schedules(W1maize regulated deficit irrigation schedule at jointing stage,W2 maize regulated deficit irrigation schedule at filling stage and W3 maize full irrigation schedule at full growth stage)from 2021 to 2080,the highest values of maize yield and crop evapotranspiration are in W3.From the response of WUE and crop evapotranspiration,the W1’s ET_cunder RCP4.5 scenario is significantly lower than that under the other two schedules,while the response of WUE and maize yield reflects that there is no significant difference between the three schedules of WUE under RCP8.5 scenario.