Study On Construction And Variation Of Specified Water Suitability Index For Maize Based On Yield Loss

Maize is an important food crop in China.Water deficit during the growth period of maize has always been the main factor affecting the yield of it.With the global climate change,the spatial and temporal distribution of precipitation in China is uneven and it fluctuates greatly from year to year.Droughts and floods occur frequently,which pose a serious threat to the food security of maize.Although the establishment of various drought and flood indices have greatly enriched the content of agrometeorological services,the drought and flood indicators for specific crops are still quite lacking.Based on the theoretical analysis and the characteristic of gradual accumulation of yield loss,this study constructed a specified water suitability index for maize based on yield loss and used the daily ground observation data at 106 meteorological stations in Northeast China(Heilongjiang,Jilin,Liaoning,east four league of Inner Mongolia)during the period of 1960~2017 and maize yield data for 34 sites from 1992~2016 to illustrate the parameterization scheme for yield reduction in various growth stages of SWSIM.The specific research is as follows:1.A general method for constructing specific crop moisture suitability index was proposed.Based on the characteristics of cumulative accumulation of crop yield losses,this paper used a step-by-step correction by multiplication to construct an index that combined moisture deficit and yield losses during the crop growth period.Based on maize yield data in Northeast China,the specific yield reduction parameters for each growth stage of SWSIM for maize were determined and tested indicator capacity of it.It provided a methodological reference for the construction of specific crop drought and flood index.2.Using the meteorological disaster data and production data to verify the effectiveness of SWSIM's indication capability in the northeast region.Compared with the crop water deficit index,SWSIM constructed in this paper could capture more typical drought and flood years accurately and indicated areas that maize to be affected in drought better.SWSIM responded to changes in precipitation,temperature and wind significantly.In the early growth stage of maize,precipitation was the key meteorological factor restricting the vegetative growth of maize;During the period from jointing to tasseling,precipitation in northwestern Liaoning Province,western Jilin Province,southwestern Heilongjiang Province and east four league of Inner Mongolia was still the key meteorological factor for vegetative and reproductive growth of maize;In most parts of Liaoning Province and northwestern Heilongjiang Province,temperature was the key meteorological factor that affected the yield;In the later stage of maize,the effect of precipitation on the yield was weakened and the temperature conditions were more conducive to grain filling to ensure the yield of maize.SWSIM could be used as an evaluation indicator for drought and flood disasters in Northeast China and then to evaluate the future water suitability during the growth stage of maize.3.In this paper,the CMIP5 global climate model data were used to calculate SWSIM from 2020 to 2099.In the next 21 st century It would not find any obvious long-term trends in SWSIM but there would be significant interdecadal fluctuations.The water suitability in the northeast would be better than that in the south.SWSIM was highest in RCP4.5 scenario,next in RCP2.6 scenario and lowest in RCP8.5 scenario among the three emission scenarios.With the increase of temperature,the water demand for maize at different growth stages and total growth period would have increased.The largest increasement of water demand would be in southeastern of Liaoning province and Jilin provinces in RCP8.5.Although the water demand for maize had increased compared to the reference period(1980-2005),the increasement of precipitation would partially compensate the increasement of water demand caused by higher temperature.The water suitability and the yield of maize in Northeast China during the growing period would not show a significant downward trend.All in all,the specified water suitability index constructed in this paper can reflect the impact of water deficit on maize yield and have good verification results on applicability assessment in Northeast China.It provides reference methods for the construction drought and flood indicators of specific crop.