Abstract: To evaluate the effect of real-time and site-specific N management on rice yield and its quality, the experiments under field conditions were conducted with indica hybrid rice Liangyoupei9(LYP9) and Shanyou63(SY63) in 2004 and 2005. The results showed that grain yield of LYP9 and SY63 under N-application treatment increased by 21.12%-57.65%, 15.00%-31.18% compared to no N-application treatment respectively based on the Real-time N Management (RTNM); grain yield of LYP9 and SY63 under N-application treatment increased by 45.44%-50.71%, 28.53%-32.40% compared to no N-application treatment respectively based on the Site-specific N Management(SSNM). The recommended SPAD threshold were 38-41 for LYP9, and 36-39 for SY63, which might obtain higher grain yield and better grain quality when RTNM were adapted for nitrogen management. The optimal SPAD threshold for LYP9 and SY63 were 38-39 and 36 respectively, when nitrogen management based on SSNM. It clearly demonstrated that the milling quality, apparent features, protein content of LYP9 was noticeably improved under a proper SPAD threshold based on the SSNM both in 2004 and 2005; For SY63, its quality could not be improved in SSNM while the SPAD threshold recommendation based on the grain yield performance. The results indicate the possibility of harmonizing the conflict of rice quality and grain yield by using SSNM based on the recommendation SPAD threshold value of 38-39 for LYP9 and 36 or so for SY63.

Key words: Rice, SPAD threshold, Real-time and Site-specific Nitrogen Management, Grain yield, Grain quality