Nitrogen (N) is one of the main nutrients that drive rice grain yield and is intensely managed especially in lowlands under irrigated conditions. A set of experiments was conducted in mid‐ and high‐altitude sites in Rwanda to investigate the response of five genotypes under different sowing dates and different N management. Genotype grain yields were higher and more stable at mid‐altitude across sowing dates. N rates strongly affected grain yield at mid‐altitude (p < .0001), but not at high altitude. Postponing basal N had positive effects on yield and yield components in both sites, with more pronounced effects at high altitude. Increasing N rate beyond 120 kg/ha led to a decrease in percentage of panicles per tiller and spikelet fertility and a decrease in grain yield due to excessive tillers at both high altitude and mid‐altitude. Thus, basal N application should be recommended at high altitude and the increase in N rate up to 120 kg/ha at mid‐altitude. A strict observation of recommended planting date should be followed at high altitude, and the use of cold‐tolerant genotypes is encouraged.

中文翻译：

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海拔，温度和氮素管理对对比低地水稻品种产量和产量构成的影响

氮是驱动稻米产量的主要营养元素之一，尤其在灌溉条件下的低地，氮素得到严格管理。在卢旺达的中高海拔地区进行了一系列实验，以调查五种基因型在不同播种日期和不同氮素管理下的反应。在整个播种期的中海拔地区，基因型谷物产量更高且更稳定。氮素含量严重影响了中海拔地区的谷物产量（p <.0001），但不在高海拔地区。推迟基础氮对两个部位的产量和产量构成有积极影响，在高海拔地区则更为明显。氮肥含量增加到超过120 kg / ha时，由于在高海拔和中海拔地区过度耕作，每穗分pan的穗数百分比和小穗肥力降低，谷物产量下降。因此，应建议在高海拔地区施用基础氮肥，在中海拔地区氮肥利用率应增加至120 kg / ha。在高海拔地区应严格遵守建议的播种日期，并鼓励使用耐寒基因型。