The cultivation area of upland crops such as soybeans, wheat, barley, and buckwheat in fields converted from paddy fields are increasing as farmers seek to stabilize their income in rice-based farming systems in Asia. However, excess water and waterlogging stress in these converted paddy fields reduces the yields of upland crops, especially buckwheat. To explore ways to alleviate excess water or waterlogging stress on buckwheat, we (1) analyzed rainfall and yield data from 2015 to 2021 to determine the effect of high-rainfall days on yield in fields with or without subsurface drainage, (2) determined the effect of raised-bed planting on yield and yield components of buckwheat plants grown in fields with or without subsurface drainage, and (3) conducted a 3-year field trial to determine the effect of raised-bed planting on soil water conditions and buckwheat growth and yield in fields without subsurface drainage. Yield was significantly negatively correlated with number of days with daily precipitation of > 30 mm in fields without subsurface drainage, but was not correlated in fields with subsurface drainage. The average yield (SD) of 78 plots without subsurface drainage was 7.49 (9.57) g m⁻² and that of 21 plots with subsurface drainage was 40.1 (25.5) g m⁻². In fields without subsurface drainage, raised-bed planting resulted in a dramatic increase in yield compared to flat-bed planting, but there was no such difference in fields with subsurface drainage. In 2 years of the 3-year field trial in fields without subsurface drainage (excluding 1 year with exceptionally high rainfall), the yields of raised-bed planting were more than double those of flat-bed planting as a result of improved vegetative and reproductive growth. Further, raised-bed planting improved the indexes of drainage and excess water and decreased the average soil water content, which were significantly correlated with yield. Our results indicate that (1) subsurface drainage would contribute to improving buckwheat yields under conditions of heavy rainfall, and (2) in fields without subsurface drainage, raised-bed planting increases buckwheat yields through improving soil water conditions and both vegetative and reproductive growth.

大豆、小麦、大麦、荞麦等旱作作物种植面积在亚洲，随着农民寻求在以水稻为基础的耕作系统中稳定收入，由稻田改造成的田地面积正在增加。然而，这些经过改造的稻田中的过量水分和涝害会降低旱地作物的产量，尤其是荞麦。为了探索减轻荞麦过量水分或涝害压力的方法，我们 (1) 分析了 2015 年至 2021 年的降雨量和产量数据，以确定高降雨天数对有或没有地下排水的田地产量的影响，(2) 确定了高床种植对在有或没有地下排水的田间种植的荞麦作物产量和产量构成的影响，以及 (3) 进行了为期 3 年的田间试验，以确定高床种植对土壤水分条件和荞麦生长的影响和没有地下排水的田地的产量。在没有地下排水的田地中，产量与日降水量 > 30 毫米的天数显着负相关，但在有地下排水的田地中不相关。78 个没有地下排水的地块的平均产量 (SD) 为 7.49 (9.57) gm⁻²而 21 个有地下排水的地块为 40.1 (25.5) gm ⁻². 在没有地下排水的田地中，与平床种植相比，高架种植导致产量显着增加，但在有地下排水的田地中没有这种差异。在没有地下排水的田地进行的为期 3 年的田间试验中，有 2 年（不包括 1 年降雨量特别大的年份），由于营养和繁殖的改善，高架床种植的产量是平床种植的两倍多生长。此外，高床种植改善了排水和多余水分指标，降低了土壤平均含水量，这与产量显着相关。我们的结果表明 (1) 地下排水有助于在强降雨条件下提高荞麦产量，以及 (2) 在没有地下排水的田地中，