Effect of different nitrogen application treatments on the photosynthetic characteristics and nitrogen fertilizer use efficiency of Bainong 207

In order to investigates the photosynthetic characteristics and nitrogen use efficiency of Bainong207(BN207) under different nitrogen managements so as to establish optimal nitrogen management and achieve the goal of green, high-yield, and efficient cultivation, using BN207 as the experimental material, five different nitrogen gradients were set, namely 0 (N0), 120 (N120), 180 (N180), 240 (N240), and 360 (N360) kg/hm². The changes in photosynthetic performance, chlorophyll fluorescence parameters, and leaf area index (LAI) during the mid to late grain filling stages of wheat, as well as their effects on biomass, nitrogen use efficiency, and yield. were analyzed. The results indicated that compared to N0, in N180, N240 and N360 groups, the chlorophyll fluorescence parameters of BN207, including F_V/F_M (the maximum quantum yield of PS Ⅱ under dark adaptation), ET_O/RC (the energy captured by a unit reaction center for electron transport), LAI, the accumulation of grain nitrogen, biomass, and yield, increased by 0.71%-4.87%, 3.45%-5.70%, 117.22%-157.64%, 62.67%-53.98%, 39.30%-57.01%, and 27.87%-28.92%, respectively. The peak values of the OJIP curve and nitrogen use efficiency in all groups decreased, but there were no significant differences among the nitrogen treatments. Additionally, the net photosynthetic rate (P_n) of BN207 in the N180 group was significantly higher than in other groups, indicating that BN207 was more conducive to achieving the goal of green, high-yield, and efficient cultivation in the N180 group. The linear plus plateau results indicated that when the nitrogen application reached 172.14 kg/hm², the yield of wheat reached a plateau. In conclusion, the optimal fertilization rate for BN207 was 172.14 kg/hm², and this result could provide a theoretical basis for high-yield cultivation management of BN207 in the North China Plain region.