Nitrogen plays a vital role in regulating leaf senescence and yield formation in rice (Oryza sativa L.). However, little information is known about the effects of N rates on the growth and grain yield of rice plants with leaf early senescence. This study used a leaf early‐senescent rice mutant (osled) and its wild type (WT) (93‐11) and investigated how N rates of 0 kg ha^–1 (0N), 240 kg ha^–1 (240N), and 360 kg ha^–1 (360N) influenced the main agronomic and physiological performance of the mutant osled. The results showed that 240N and 360N treatments increased grain yield of the osled plants by 201.5–222.9% and 266.4–287.9% as compared with 0N treatment, respectively, with the 360N treatment maintaining a similar agronomic nitrogen use efficiency (ANUE) as 240N. Leaf activity of the osled plants was enhanced with N supply levels showing increased leaf area, chlorophyll content, N content, and activities of N‐related enzymes and photosynthetic rate, and lowered malondialdehyde content. In contrast to 0N, the two N treatments significantly increased plant height, aboveground biomass, tiller number and percentage of productive tillers of both rice genotypes. Compared with 240N, the 360N treatment particularly increased grain weight and percentage of filled grains for the osled plants through improving leaf activity, root activity, and grain activity. These results verify that N treatment regulates leaf senescence and reduces yield loss of the osled plants, and simultaneously implied that the osled plants more positively respond to high N supply.

中文翻译：

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施氮量对叶片早衰水稻突变体生长和籽粒产量的影响

氮在调节水稻（Oryza sativa L.）的叶片衰老和产量形成中起着至关重要的作用。但是，关于氮含量对具有叶片早期衰老的水稻植物生长和籽粒产量的影响知之甚少。这项研究使用了叶片早衰稻突变体（osled）及其野生型（WT）（93-11），并研究了氮含量如何分别为0 kg ha ^–1（0N），240 kg ha ^–1（240N）和360 kg ha ^–1（360N）影响了突变体雪橇的主要农艺和生理性能。结果表明，240N和360N治疗增加的粮食产量osled与0N处理相比，分别增加了201.5–222.9％和266.4–287.9％，而360N处理则保持了与240N相似的农艺氮利用效率（ANUE）。氮素供应水平提高了单株植物的叶片活性，氮素供应水平提高了叶片面积，叶绿素含量，氮含量以及氮相关酶的活性和光合速率，并降低了丙二醛含量。与0N相比，两种氮处理均显着增加了两种基因型水稻的株高，地上生物量，分till数和生产性分till的百分比。与240N相比，360N处理特别增加了单粒重的粒重和填充颗粒的百分比通过改善叶片活性，根系活性和谷粒活性来种植植物。这些结果证实了氮处理调节了叶片衰老并减少了单株植物的产量损失，同时暗示了单株植物对高氮供应有更积极的反应。