Although one-time application of a single polymer-coated urea (PCU) can minimize the N loss in paddy field and improve nitrogen use efficiency (NUE) in relative to rapid-release urea (RU), it shows a uncertainty in increasing rice yield. There is a proposal that one-time application of PCU mixed with RU can synergistically increase grain yield and NUE. However, few studies focus on the response of roots and rhizospheric bacteria to the nitrogen (N) management. We investigated the issue based on a two-year field experiment using an hybrid variety Yongyou 2640, with four N managements including N omission (0 N), split application of RU (Control), one-time application of 100 % PCU (T1) and one-time application of 70 % PCU + 30 % RU (T2). Results showed that, compared with those in the control, grain yield and total number of spikelets were significantly increased in the T2 treatment while they were comparable in the T1 treatment. Both T1 and T2 remarkably increased N recovery efficiency (RE). During booting, the highest α diversity in rhizospheric bacterial communities was observed in the T2 treatment, followed by T1 and control. Among the root morph-physiological traits, the redundancy analysis (RDA) highlighted the significant contribution of root oxidation activity (ROA) to bacterial communities. Additionally, the linear discriminant analysis effect size (LEfSe) identified nine specific genera taxa in the T2 treatment. The abundances of these genera, particularly the , highly correlated with ROA, root H-ATPase activity, organic acid content, microbial biomass carbon and nitrogen (MBC and MBN) contents, MBC-to-MBN ratio, and the N accumulation during booting (NABT). These traits exhibited notable advantages in the T2 treatment, which contributed significantly to the grain yield, RE, and the total number of spikelets. Interestingly, the nitrate-N content was most significantly increased in T2, followed by T1 and control, rather than the ammonium-N content, which was also highly correlated with the abundance of . In conclusion, a combination of PCU with RU could coordinate root activity and bacterial communities, especially the ROA and and facilitate the consumption or cycling of nitrate-N while mitigating the risk of its mobility, leading to a remarkably increase in NABT, and consequently, synergistically increase grain yield and NUE.

中文翻译：

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水稻根系活性和根际细菌对氮管理的响应（Oryza sativa L.）


虽然相对于速释尿素（RU）一次性施用单一聚合物包膜尿素（PCU）可以最大程度地减少稻田氮素损失并提高氮素利用效率（NUE），但其在提高水稻产量方面存在不确定性。有建议认为PCU与RU混合一次性施用可以协同提高粮食产量和NUE。然而，很少有研究关注根和根际细菌对氮（N）管理的反应。我们通过对杂交品种甬优2640进行了为期两年的田间试验，进行了四种氮管理，包括漏氮（0 N）、分次施用RU（对照）、一次性施用100%PCU（T1）。一次性应用 70% PCU + 30% RU (T2)。结果表明，与对照相比，T2处理的籽粒产量和总穗数均显着增加，而T1处理则与对照相当。 T1 和 T2 均显着提高了氮回收效率 (RE)。在孕穗期间，在 T2 处理中观察到根际细菌群落的 α 多样性最高，其次是 T1 和对照。在根形态生理特征中，冗余分析（RDA）强调了根氧化活性（ROA）对细菌群落的显着贡献。此外，线性判别分析效应大小 (LEfSe) 确定了 T2 处理中的 9 个特定属类群。这些属的丰度，特别是 ，与 ROA、根 H-ATP 酶活性、有机酸含量、微生物量碳和氮（MBC 和 MBN）含量、MBC 与 MBN 比率以及孕穗期间的氮积累高度相关。全国广播电视协会）。 这些性状在T2处理中表现出显着的优势，对籽粒产量、RE和小穗总数贡献显着。有趣的是，硝酸盐-N 含量在T2 中增加最显着，其次是T1 和对照，而不是铵-N 含量，后者也与 的丰度高度相关。总之，PCU 与 RU 的组合可以协调根系活性和细菌群落，特别是 ROA，并促进硝酸盐-N 的消耗或循环，同时减轻其移动风险，从而导致 NABT 显着增加，因此，协同提高粮食产量和氮肥利用效率。