Irrigation Management Decision And Response Study To Climate Changes For Winter Wheat Based On DSSAT In Henan Province

Five varieties of winter wheat holding the vastest planting area in Henan Province were chosen that CERES-Wheat model, which is supported by Decision Support System for Agrotechnoloy Transfer (DSSAT) from America, was evaluated by parameters' calibrations, validations and sensitivity analysis based on collecting of historical field observed information, daily meteorological data and major soil parameters from 17 areas. The model was utilized for studying the spatial distribution of Photo-Temperature Productivity (PTP) and increasable productivity by water, and then, 100mm limited irrigation test was performed at Zhengzhou station which has higher increasable productivity, to assess the influence of limited irrigation on yields, yield's structure and water use efficiency etc. Finally, 13 different stations were chosen that variations of yield and crop water utilization conditions under two scenarios of climatic changes were investigated. The results showed that:The correlation coefficient (R²) and NRMSE between simulated and measured yields in Henan were 0.82 and 13.04% respectively, corresponding values were 0.88 and 2.30% for developmental phase simulation, and those numbers are almost perfect. The model did better at computing stem biomass than total biomass, but with a little higher simulation errors of green leaves biomass and LAI because of less-than measured values.Henan is rich in photo-thermal resource, 10 years average PTP in the whole province is between 5732 and 10751 kg/ha, and the value is much lower than the results from formula calculation. Spatial distribution of PTP exhibits highest in most part of north province and Luohe, Pingdingshan area, while lowest in west mountainous region; Increasable productivity of winter wheat is considerable, which is between 2502 and 8598kg/ha, with the distribution pattern of higher in most of north and part of middle and east area of the province, lower in west mountain land and lowest in south part of Henan province.Limited irrigation test proved that: watering during wintering assists seedling protection, irrigating during shooting stage is good for spikelet enrichment, and watering in grain filling stage accelerates dry matter accumulating in the kernel, shooting stage is the best time for limited irrigation. On the whole, irrigating twice had the greatest rate of yield increase than three times than once and non-watering treatment. In respect of water use efficiency, in the years short of precipitation, irrigating twice won the largest WUE than three times and once, while irrigational water could be best utilized for shooting stage; In the normal years, irrigating more times with a small amount gained the highest WUE than twice and once, watering 100mm in all at shooting and grain filling stages gained the largest irrigational WUE.Climate changes has a complex influence on winter wheat in Henan Province, if direct fertilizing effect of CO₂ was considered that the yields would go up by 8% for the whole province, no matter under A2 or B2 scenarios, and wheat's water demand would come down, WUE improves; Contrarily, without direct fertilizing effect, wheat's production would reduce 7% nearly compare to present level except several exceptional stations in northeast area, at the same time, water demands of wheat would stay on or even become more.