Abstract:Two early indica rice cultivars of Xiangliangyou 68 and Zaoxian 65 were used to study nitrogen uptake,utilization,yield and yield components as affected by different split N application strategies when the total nitrogen application amount was 150 kg/ha in the north rimland of double-cropping rice.Results showed that reducing N application before transplanting and at tillering stage but increasing N application at booting stage could increase rice yield and nitrogen uptake and utilization,by increasing leaf nitrogen content and SPAD in top 3 leaves during heading stage to mature stage,and increasing LAI and effective leaf area percentage.When nitrogen fertilizer was applied before transplanting(50%),tillering(25%),booting (25%),both hybrid and conventional rice cultivars had highest yield.The main benefit of postponing N fertilizer application time on yield formation was related to its improved splitting and timing of fertilizer N applications leading to a more balanced supply of N nutrition for rice growth than the common fertilizer practice,and to increase total amount of N-absorption(ANA).Nitrogen fertilizer use efficiency(NUE) increased with the percentage of panicle fertilizer,but the agronomic use efficiency of N fertilizer had better relationship with yield. It is concluded that the split application of N before transplanting(50%),at tillering stage(25%) and at booting stage(25%) is a rational N application strategy in the north rimland of double-cropping rice.