实时实地氮肥管理对不同杂交水稻氮肥利用率的影响

 【目的】探讨两系和三系杂交水稻在实时实地氮肥管理模式下对氮素的吸收和氮肥利用率的差异。【方法】试验于2004和2005年在大田条件下，以两优培九、汕优63为材料比较研究了实时实地氮肥管理模式下不同叶绿素仪（SPAD）预设阈值对其吸氮特性与氮肥利用率的影响。【结果】水稻叶片叶色存在基因型差异，汕优63顶叶的SPAD值比两优培九平均低1.7～2.0个数值单位。在实时氮肥管理模式下，施氮量与SPAD预设阈值呈指数相关关系。对于汕优63而言，Nrate=0.9956 e0.132 SPAD （r2=0.8338**），对于两优培九则为Nrate=0.1565 e0.173 SPAD（r2=0.9508**）。在SPAD预设阈值介于36～40的范围内，若要保持两个品种同一时期顶叶的SPAD值相同，汕优63比两优培九需要多施用氮肥37.3 kg N?ha-1。【结论】在实时实地氮肥管理模式下，当氮肥平均用量接近160 kg N?ha-1时，两优培九的吸氮能力、氮肥吸收利用率和氮素籽粒生产效率与汕优63相当；其氮素干物质生产效率、氮肥农学利用率高于汕优63；其氮素收获指数低于汕优63。此外，两优培九比汕优63表现出较高的耐肥抗倒伏能力。

Effect of Real-time and Site-specific Nitrogen Management on Various Hybrid Rice

Site-specific N management (SSNM) and real-time N management (RTNM) improves fertilizer-N use efficiency of irrigated rice. This study was conducted to compare the most popular hybrid varieties, three-line hybrid rice-Shanyou63 (SY63) and two-line hybrid rice-Liangyoupei9 (LYP9), in their response to N application and fertilizer-N use efficiency under RTNM and SSNM in field conditions in 2004 and 2005. 【Method】The two varieties were grown under eight and six N treatments in 2004 and 2005, respectively, in Hubei, China. N treatments included a zero-N control, a SSNM and several RTNM with different chlorophyll meter (SPAD) thresholds. 【Result】The results showed that, color of rice leaves had genotypic difference between varieties, the SPAD reading of SY63 had 1.7-2.0 units lower than that of LYP9 while both varieties were under zero or the same fertilizer-N rates. The fertilizer-N rate showed significant exponential correlation with the SPAD threshold based on RTNM for both varieties. The equations for SY63 and LYP9 were, N rate=0.9956 e0.132 SPAD (r2=0.8338**), and N rate=0.1565 e0.173 SPAD (r2=0.9508**), respectively. It was found that, additional fertilizer-N 37.3 kgN.hm-2 was required for SY63 to maintain the same SPAD value in comparison with that of LYP9, when SPAD thresholds were among 36-40 under RTNM. 【Conclusion】When average fertilizer-N rate was around 160 kgN.hm-2, LYP9 showed similar capacity and characteristics on N uptake, N recovery use efficiency, and nitrogen use efficiency based on grain production, in comparison with that of SY63. But LYP9 had greater nitrogen use efficiency based on biomass production, fertilizer-N agronomic use efficiency, in comparison that of SY63 respectively. However, SY63 had greater nitrogen harvest index than that of LYP9. The results also showed that, LYP9 had greater tolerance against lodging than that of SY63 when excessive fertilizer-N applied.