Abstract: To explore the feasibility of reducing N application and maintaining high grain yield through rice genetic improvement, 20 rice varieties, including Jingliangyouhuazhan, Shengtaiyou 722, Fengtianyou 553, Wuyou 308, Yuejingsimiao 2, 4HD005, Chuanyousimiao, Hengfengyou 701, Guoyou 9113, Yundan 4, 9311A/R672, Quanxiangyou 6, Huarun 2, Wushansimiao, Tianyouhuazhan, Shenyou 513, Liangyou 336, Chunliangyouyouzhan, Shengtaiyou 018 and Juliangyou 751, were evaluated at a reduced N rate (120 kg·hm^-2, 1/3 lower than the local high-yield and high-efficiency practice) in 2015 and 2016. Grain yield, yield components, tillers number, biomass accumulation and allocation, sink-source characters and N uptake and utilization were measured. Significant differences in grain yield were found among the tested varieties, ranging from 4.99 to 7.18 t·hm^-2 in 2015 and from 6.22 to 7.73 t·hm^-2 in 2016. Compared with the control, Yuejingsimiao 2, the varieties with 10% higher yield in 2015 were Jingliangyouhuazhan, Shengtai you 722, Fengtianyou 553, Wuyou 308, Hengfengyou 7011, Guoyou 9113, 9311A/R672 and Quxiangyou 6, the varieties with 10% higher yield in 2016 were Jingliangyouhuazhan, Shentaiyou 722, Fengtianyou 553, Tianyouhuazhan, Shenyou513 and Juliangyou 751. Among them, Jingliangyouhuazhan (two years), Guoyou 9113, Quxiangyou 6, Shenyou 513 and Juliangyou 751 were greater than 7.00 t·hm^-2, which were at least 20% higher than the control variety. Under reduced N input, grain yield were significantly correlated with total biomass and sink size. While no significant correlations were found between grain yield and yield components, tiller number and biomass accumulation at specific growth stages. Varieties with high yield under reduced N input had comparable total N uptake, but higher N use efficiency for grain production (NUE_g). These results showed that it is feasible to maintain high yield under reduced N input through genetic improvement. Greater biomass, larger sink size, and higher NUE_g are important characteristics for the varieties with high-yield under reduced N input. The findings provide reference for the breeding of varieties with high-yield under reduced N input.

Key words: rice, reduction of N, biomass, sink capacity, N use efficiency for grain production

摘要： 为探索通过品种改良实现在减少施氮的条件下维持水稻高产的可行性,明确减氮高产品种特征,本研究于2015-2016年在较当地高产高效栽培减氮三分之一(施氮量120 kg·hm^-2)的条件下,以粤晶丝苗2号为对照,分析了晶两优华占、盛泰优722、丰田优553、五优308、粤晶丝苗2号、4HD005、川优丝苗、恒丰优7011、国优9113、云氮4号、9311A/R672、荃香优6号、华润2号、五山丝苗、天优华占、深优513、两优336、春两优油占、盛泰优018、聚两优751共20个水稻品种的产量及其构成、分蘖动态、物质生产、源库特性和氮素吸收利用。结果表明,参试水稻品种间产量差异显著(P<0.01),2015年和2016年分别为4.99~7.18 t·hm^-2和6.22~7.73 t·hm^-2;产量较对照高10%以上的品种为2015年的晶两优华占、盛泰优722、丰田优553、五优308、恒丰优7011、国优9113、9311A/R672和荃香优6号,以及2016年的晶两优华占、盛泰优722、丰田优553、天优华占、深优513和聚两优751,其中晶两优华占(两年)、国优9113、荃香优6号、深优513和聚两优751的产量均超过7.00 t·hm^-2,且较对照高20%以上,表明通过品种改良实现减氮高产是可行的。在减氮条件下,水稻产量与总生物量、库容量均呈显著正相关,而与产量构成因子、单位面积茎蘖数、不同阶段物质积累量及叶源大小均无显著相关性。减氮条件下,高产水稻品种的总吸氮量不高,但其氮素籽粒生产效率较高,表明生物量大、库容量大、氮素籽粒生产效率高是减氮高产水稻品种的重要特征。本研究结果为减氮高产水稻品种的选育提供了参考依据。

关键词: 水稻, 减氮, 生物量, 库容量, 氮素籽粒生产效率