Responses Of Spring Wheat Growth And Yield To Meteorological And Agricultural Drought During Growth Period

Agriculture is an important support to achieve balanced economic development,and at the same time,agriculture is the field most affected by weather and climate.The impact of drought on agriculture is related to national food security and social stability.Therefore,exploring the effects of different types of drought on the growth process and yield of spring wheat can reduce the effects of drought on the growth and yield of spring wheat,to provide reference for improving spring wheat yieldIn this paper,the planting area of spring wheat in China is divided into three subregions,namely,sub-region I-Northeast Plain,sub-region II-Northern Arid and Semi-arid Region,and sub-region III-Qinghai-Tibet Plateau Region.Based on SPEI and SMDI of 1-9 months in the growth period of spring wheat,the historical period（1961-2020）and future period（2021-2100）are analyzed and analyze the correlation between meteorological drought and agricultural drought.Dsat-ceres-wheat model was used to simulate the phenological period,LAI_max,biomass and yield of spring wheat in history and future.At last,the correlation between SPEI and SMDI in each month and time scale and the data of LAI_max,biomass and yield of spring wheat was analyzed to explore the effects of meteorological and agricultural drought on the growth process and yield of spring wheat.The main results are as follows:（1）The temporal and spatial evolution law of drought during growth period in spring wheat planting area was expounded.Meteorological droughts occur frequently,and meteorological droughts of varying degrees occur in almost every month during the growth period of spring wheat,among which droughts occur frequently from March to May.The meteorological drought in sub-region III-Qinghai-Tibet Plateau is more frequent than that in sub-region INortheast Plain and sub-region II-Arid and Semi-arid Region in North China during the spring growth period of wheat.Severe drought and extreme drought occurred during the growth period.The change of agricultural drought index SMDI is relatively stable.Compared with the0～10 cm soil layer,the agricultural drought in the 10～40 cm soil layer of subarea I-Northeast Plain is more serious.After 2000,severe and long-lasting agricultural drought occurred in the Northeast Plain and the Qinghai-Tibet Plateau,and the frequency of drought was also high.SSP1-2,2021～2100.6.Under the scenarios of SSP2-4.5,SSP3-7.0 and SSP5-8.5,the agricultural drought in the 0-10 cm soil layer during the growth period of spring wheat is mostly on the time scale of 2-5 months,and the frequency of drought is high from June to September.Under the four scenarios from 2021 to 2100,the agricultural drought in each time scale during the growth period of spring wheat has little change,and generally presents dry-wet alternation,but the frequency of agricultural drought is relatively high.There is a good correlation between spring wheat drought and meteorological drought,and the response time of spring wheat agricultural drought to meteorological drought is mostly 1～2 months.（2）Based on DSSAT-CERES-Wheat model,the growth and yield of spring wheat were simulated.The simulated R² of DSSAT-CERES-Wheat on flowering stage,maturity stage and yield of spring wheat is above 0.84,and the DSSAT-CERES-Wheat model can well simulate the growth process and yield of spring wheat.The LAI_max,biomass and yield of spring wheat subarea in historical period I-Northeast Plain are relatively small,However,the spring wheat LAI_max,biomass and and yield of spring wheat in sub-region III-Qinghai-Tibet Plateau are larger than those in other two sub-regions,while the interannual changes of LAI_max,biomass and yield of spring wheat in subregion II-arid and semi-arid areas in northern China are relatively gentle.In the future,the LAI_max,biomass and the average yield of each division in the growth period are larger than those in the historical period.In the future,the LAI_max,biomass and average yield of spring wheat during the growth period from 2061 to 2100 also showed a slight increase compared with that from2021 to 2060.There is no obvious rule among the scenarios in the future.（3）The effects of different types of drought on the growth and yield of spring wheat were revealed.According to the correlation analysis of SPEI,SMDI at 0-10cm depth and SMDI at 10-40cm depth with the growth and yield of spring wheat,and the correlation analysis of linear tendency rate,SMDI at 0-10cm is the most critical drought index affecting the growth process and yield of spring wheat.The drought indexes in key months and key time scales that affect the growth period of spring wheat,the aboveground biomass in mature period and the yield of spring wheat are not quite the same in different regions in history,but on the whole,the drought indexes in short time scales have a greater impact on the growth and yield of spring wheat.Drought in the early and middle growth period has a great influence on the growth of spring wheat leaves.Drought in the middle and late growth period has a great influence on the aboveground biomass accumulation and yield of spring wheat.The correlation between SMDI at 0-10cm and spring wheat LAI_max,biomass at maturity and spring wheat yield in the future period is slightly worse than that in the historical period.The laws and historical periods of the key growth period and the corresponding optimal time scale which have a great influence on the growth and yield of spring wheat are similar,and the drought index of short time scale has a greater influence on the growth and yield of spring wheat.Drought in the middle and late growth period has a great influence on the growth and yield of spring wheat.This study has reference significance for how to effectively deal with the drought during the growth period of spring wheat and further increase the yield of spring wheat in China to meet the national food supply.