Rice (Oryza sativa L.) ratooning has recently attracted attention since it possesses higher yield potential compared to conventional rice‐growing methods; however, it requires a longer growing season. Field experiments were conducted in southwestern Japan in 2017 and 2018 to determine the effect of harvest time (early and normal) and cutting height (high and low) of the first crop on grain yield of the first and second crops using a high‐yielding line under high N application and high air temperature conditions in rice ratooning. The highest total yield of the first and second crops was produced when the first crop was harvested at the normal time with the high cutting height in 2018. This yield reached 14.4 t ha⁻¹, which is equivalent to threefold the average yield achieved by Japanese farmers. Plants harvested at the high cutting height produced higher grain yield of the second crop because of the larger spikelet number m⁻² and better grain filling using abundant leaf area index (LAI) and nonstructural carbohydrate (NSC) in the stubble. In southwestern Japan, the daily mean air temperatures during the early growth stage of the first crop and the late ripening stage of the second crop have been increasing over time. Our results suggest that increasing LAI and NSC in the stubble by harvesting at the normal time harvest with the high cutting height under high level N application conditions may provide an adaptive strategy to increase yield with a rice‐ratooning system as growing seasons extend due to global climate change.

中文翻译：

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在气候条件变化的情况下，通过再生方法突破水稻产量壁垒：日本西南部水稻种植系统的范式转变

水稻（Oryza sativa L.）的再生问题最近引起了人们的注意，因为与传统的水稻种植方法相比，它具有更高的产量潜力。但是，这需要更长的生长季节。2017年和2018年在日本西南部进行了田间试验，以高产线确定第一季作物的收获时间（早期和正常）和and割高度（高和低）对第一季和第二季谷物产量的影响在高氮肥和高气温条件下水稻再生。第一类和第二类作物的总产量最高，是在正常时间收获第一类作物并于2018年收获时的最高高度。该产量达到14.4 t ha ^-1，相当于日本农民平均单产的三倍。由于小穗数m ^-2较大，在高采伐高度收获的植物第二季作物的籽粒产量更高并在茬中使用丰富的叶面积指数（LAI）和非结构性碳水化合物（NSC）更好地填充谷物。在日本西南部，第一作物的早期生长阶段和第二作物的成熟后期的日平均气温随着时间的推移一直在增加。我们的研究结果表明，在高水平施氮条件下，通过在正常时间收获并以高cutting割高度收获时，增加茬中的LAI和NSC，可能提供一种适应策略，因为稻纵行系统因全球干旱而延长了产量，从而增加了产量气候变化。