Abstract:Aiming to study the effects of regulated deficit irrigation with different nitrogen application levels on winter wheat，a field experiment was conducted in Xinxiang County，Henan Province，located in the Huang-Huai-Hai Plain from 2021 to 2022. Three nitrogen application levels：N1 (120kg/hm2)，N2(240kg/hm2) and N3(360kg/hm2)，and three regulated deficit levels during the stage of jointing-heading：moderate deficit (irrigation amount 18mm，M)，light deficit (irrigation amount 24mm，L) and control (irrigation amount 30mm，CK) were set. The results showed that the net photosynthetic rate (Pn) of winter wheat flag leaves was significantly affected by regulated deficit and nitrogen application level. After re-watering，Pn of all treatments showed different degrees of compensation growth effect，and the compensation effect was enhanced with the increase of nitrogen application rate，N3M and N3L treatments showed a super compensation effect，which was increased by 42.5% and 32.4%, respectively, compared with that before re-watering. Both the aboveground dry matter accumulation at the flowering stage and dry matter accumulation of aboveground vegetative organs at the maturity stage were increased with the increase of nitrogen application rates, while the latter was also increased with the increase of irrigation amount. However, light regulated deficit could promote the above-ground dry matter accumulation at the flowering stage, the translocation of dry matter to grain and the accumulation of nitrogen in plant and ear，and then improved winter wheat yield，water use efficiency (WUE) and nitrogen partial factor productivity (NPFP). The quadratic regression equation of winter wheat yield, WUE, NPFP and nitrogen application rate, irrigation amount was established by using Mintab 15.1 software. It was calculated that when the nitrogen application rate and irrigation amount were 214.6kg/hm2, 166.6mm，the yield was 10973.1kg/hm2，WUE was 2.7kg/m3，NPFP was 52kg/kg，the composite desirability was the highest of 0.7，and the comprehensive benefit was in line with the expected target. Therefore，light water deficit during the jointing-heading stage combined with the nitrogen application of 214.6kg/hm2 could maintain high yield and high water and nitrogen use efficiency of winter wheat，which could be used as a suitable winter wheat deficit irrigation model in this area.
