The current practice of direct seeding in East-African high-altitude rice farming systems is constrained by water availability early in the season and low temperatures later in the season at the crop's critical reproductive stage. Thus, productivity is restricted as only short-duration varieties can be grown due to the risk of crop failure. To fully exploit the yield potential of such rainfed systems, the best combination of crop establishment methods and climatic ‘best fit’ genotypes is required. In this study, nine rice genotypes were evaluated under direct seeding and transplanting in the 2016 and 2017 cropping seasons with the aim of identifying genotype by environment by management combinations best fitting the high-altitude, rainfed rice production systems. On average across all genotypes, transplanting had a positive yield effect of 18% in 2016 and 23% in 2017. Regarding the phenological development, individual phenophases were not significantly affected by transplanting relative to direct seeding; however, vegetative development stages in transplanted rice tended to be about 15% longer than when direct seeded. Even though transplanting led to extended vegetative growth, the time in the nursery allowed the plants to escape the cold spell late in the season. The results from the current study provide options to adapt cropping calendars by combining genetic resources with targeted crop management, thus improving and stabilizing yields of rainfed lowland rice farming systems at high altitude.

中文翻译：

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移植作为应对东非高海拔低地水稻生产系统非生物胁迫的一种选择

目前在东非高海拔水稻种植系统中直接播种的做法受到季节早期可用水量和季节后期作物关键繁殖阶段低温的限制。因此，由于作物歉收的风险，只能种植短期品种，因此生产力受到限制。为了充分利用这种雨养系统的产量潜力，需要作物建立方法和气候“最适合”基因型的最佳组合。在这项研究中，在 2016 年和 2017 年种植季节，对 9 种水稻基因型进行了直接播种和移栽评估，目的是通过最适合高海拔雨养水稻生产系统的管理组合，根据环境确定基因型。平均而言，所有基因型，移栽对2016年和2017年的增产效果分别为18%和23%。物候发育方面，相对于直播，移栽对单个物候期的影响不显着；然而，移栽水稻的营养发育阶段往往比直接播种时长约 15%。尽管移植导致植物生长延长，但在苗圃中的时间让植物在季节后期摆脱了寒冷。当前研究的结果提供了通过将遗传资源与有针对性的作物管理相结合来调整种植日历的选择，从而提高和稳定高海拔地区雨育低地水稻种植系统的产量。相对于直接播种，移植对单个物候期没有显着影响；然而，移栽水稻的营养发育阶段往往比直接播种时长约 15%。尽管移植导致植物生长延长，但在苗圃中的时间让植物在季节后期摆脱了寒冷。当前研究的结果提供了通过将遗传资源与有针对性的作物管理相结合来调整种植日历的选择，从而提高和稳定高海拔地区雨育低地水稻种植系统的产量。相对于直接播种，移植对单个物候期没有显着影响；然而，移栽水稻的营养发育阶段往往比直接播种时长约 15%。尽管移植导致植物生长延长，但在苗圃中的时间让植物在季节后期摆脱了寒冷。当前研究的结果提供了通过将遗传资源与有针对性的作物管理相结合来调整种植日历的选择，从而提高和稳定高海拔地区雨育低地水稻种植系统的产量。在苗圃的时间让植物在季节后期摆脱了寒冷。当前研究的结果提供了通过将遗传资源与有针对性的作物管理相结合来调整种植日历的选择，从而提高和稳定高海拔地区雨育低地水稻种植系统的产量。在苗圃的时间让植物在季节后期摆脱了寒冷。当前研究的结果提供了通过将遗传资源与有针对性的作物管理相结合来调整种植日历的选择，从而提高和稳定高海拔地区雨育低地水稻种植系统的产量。