Yield and N use efficiency as influenced by real time and site specific N management in two rice cultivars

Two rice cultivars of Yang liang you 6 (YLY6) and Pei liang you 3076 (PLY3076) were used in the field experiments to study the effects of SPAD values guided fertilization on nitrogen (N) uptake, yield and N use efficiency in two rice cultivars. The results showed that the N application rate, grain yield and N uptake increased with increment of preset SPAD values. Under real time N management practice (RTNM), the treatment of SPAD value for 41 obtained higher grain yield and N use efficiency for both YLY6 and PLY3076, besides, it could save N fertilizer by 12.8%33.3% while maintaining almost the same yield level as compared with farmers practice (FP). Under site specific N management practice (SSNM), the treatment of SPAD value for 3941 achieved higher grain yield and N use efficiency, and saved N fertilizer by 23% compared to FP. Taking the convenient management into consideration, it was suggested that the SPAD value of 3941 would be adopted as the threshold value under the site specific N management practice.