Abstract:

【Objective】To clarify the characteristics of nitrogen absorption and utilization in early-maturity late japonica rice cultivars, the grain yield components and their relationship with nitrogen uptake and utilization efficiency were investigated in comparison to a control cultivar Ningjing 1.【Method】A field experiment was conducted in the Rice Research Institute of Jiangsu (Wujin) in 2012 and 2013 with eight newly released early-maturity late japonica rice cultivars in Jiangsu Province (namely Wuyunjing 29, Wuyunjing 23, Yangjing 4227, Tongjing 981, Changnongjing 7, Ningjing 3, Zhendao 16 and Nanjing 5055) as materials.【Results】The actual grain yield of the eight new cultivars surpassed the control by 7.87% on average, with four(Wuyunjing 29, Wuyunjing 23, Yang 4227, and Tongjing 981) increased significantly (P<0.01). The total nitrogen uptake and nitrogen utilization efficiency at maturity in the eight new cultivars increased by 4.97% and 2.85%, respectively, compared to the control, which led to the improved grain yield. Further analysis revealed that the nitrogen content showed little variation among the new cultivars, while the dry matter production was significantly higher than that of the control. The nitrogen absorption before heading contributed about 80%-85% of the total in the whole growth duration. The nitrogen uptake at heading stage and heading-maturity period in the eight new cultivars were 1.35% and 25.94%, respectively, higher than that of the control. The panicle number showed limited contribution to the variation of total nitrogen uptake in the new cultivars, whereas the nitrogen uptake per panicle was 3.19% higher than that of the control. New cultivars had less than five days differences in the whole growth duration (life cycle), whereas the nitrogen uptake rate (average daily nitrogen absorption) of the new cultivars was 5.85% higher than that of the control. Correlation and path analysis revealed that larger dry matter production, daily nitrogen absorption rate, nitrogen absorption per panicle and amount of nitrogen uptake after heading contributed significantly to the higher total nitrogen absorption. In the new cultivars, the nitrogen percentage of the whole rice plants was generally higher. The nitrogen assimilated into and translocated to grains was higher in the new cultivars. All these characteristics contributed to higher total nitrogen uptake and nitrogen grain production efficiency. The nitrogen harvest index, nitrogen absorption percentage, nitrogen agronomic efficiency, and nitrogen partial production efficiency were higher in the new cultivars with more grain yield. 【Conclusion】 In short, the eight new cultivars from Southern Jiangsu Province had more nitrogen uptake and higher nitrogen utilization efficiency, and grain yield. Increasing total nitrogen uptake and improving nitrogen utilization efficiency were helpful in further raising the grain yield in rice production.

Key words: early-maturing late japonica rice cultivar, high yielding, nitrogen uptake, nitrogen utilization efficiency

摘要：

【目的】 为阐明江苏省早熟晚粳新品种氮素吸收与利用的品种差异及其影响因素,【方法】于2012-2013年在江苏（武进）水稻研究所,以江苏省新近育成的8个早熟晚粳稻为供试材料,研究其与对照在产量、氮素吸收、氮素利用上的差异,分析氮素吸收利用及影响因素。【结果】 1) 8个早熟晚粳新品种实收产量均高于对照宁粳1号,平均增加7.87%,其中,武运粳29、武运粳23、扬粳4227、通粳981极显著高于对照;新品种总吸氮量和氮素籽粒生产效率分别比对照平均增加4.97%、2.85%。随着品种吸氮量、氮素籽粒生产效率的提高,稻谷产量均增加;2)高产新品种干物质生产量高、吸氮强度大、单穗吸氮量多和抽穗后吸氮量多,导致总吸氮量多;3)高产新品种结实期茎鞘叶氮素转运量、转运率大,氮素比例下降值大,成熟期茎鞘叶氮素比例低,结实期穗氮素增加量大,成熟期穗氮素比例高,这些特征均有利于总吸氮量、氮素籽粒生产效率的提高,且对前者的促进作用明显大于后者;4)高产新品种氮素收获指数、氮肥吸收利用率、氮肥农学利用率、氮肥偏生产力等指标均高于对照,产量越高趋势越明显。总氮吸收量、氮素籽粒生产效率高的品种有利于氮素收获指数、氮肥农学利用率、氮肥偏生产力的提高,但前者的影响更大。吸氮量高的品种氮肥利用率也较高,氮素籽粒生产效率高的品种氮素干物质生产效率、氮肥生理利用率也高。【结论】 在苏南稻区,8个早熟晚粳新品种产量明显高于对照,氮肥（素）吸收利用率、总吸氮量、氮素籽粒生产效率均比对照表现出一定的优势。

关键词: 早熟晚粳, 高产, 氮素吸收, 氮素利用效率