ABSTRACT Two pot experiments were conducted to compare dry matter production and physiological responses to a wide range of irrigation levels (100% of field capacity (control: iC), 80% (i8), 60% (i6), 40% (i4), and 20% (i2) of irrigation for iC) from the beginning of the bloom stage to the full seed stage of two Japanese determinate soybean cultivars, Hatsusayaka and Sachiyutaka. The phenological stages of both cultivars were delayed correspondingly with the reduction in irrigation levels. Seed yield and total dry matter (TDM) decreased correspondingly with the reduction in irrigation, with some exceptions in which maximum results were achieved with i8 rather than iC for some traits, though the differences between i8 and iC were not significant. The proportional decrease in TDM in line with irrigation levels was due to the decrease in photosynthesis rate (Pn), and the decrease in Pn was closely related to the decrease in stomatal conductance. The response of grain yield to irrigation levels was approximated by a linear-plateau model, which indicated that these traits increased proportionally with the amount of irrigation up to a certain level, and after that, it reached a threshold. Our results showed that Hatsusayaka had higher leaf water potential and TDM than Sachiyutaka in some irrigation levels, but no evidence was found which indicates a significant difference on drought tolerance between Hatsusayaka and Sachiyutaka. Graphical Abstract

中文翻译：

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两个日本大豆品种对大范围灌溉水平的干物质生产和生理反应

摘要 进行了两个盆栽试验，以比较大范围灌溉水平（100% 田间容量（对照：iC）、80% (i8)、60% (i6)、40% (i4) 的干物质产量和生理反应）和 20% (i2) 的 iC 灌溉），从两个日本确定的大豆品种 Hatsusayaka 和 Sachiyutaka 的开花期开始到完整种子期。两个品种的物候阶段都随着灌溉水平的降低而相应延迟。种子产量和总干物质（TDM）随着灌溉量的减少而相应降低，但有些例外，在某些性状上，i8 而非 iC 获得了最大的结果，尽管 i8 和 iC 之间的差异不显着。TDM 与灌溉水平成比例的下降是由于光合速率（Pn）的下降，而 Pn 的下降与气孔导度的下降密切相关。粮食产量对灌溉水平的响应用线性高原模型近似，表明这些性状随灌溉量成比例增加，达到一定水平，之后达到阈值。我们的研究结果表明，在某些灌溉水平上，Hatsusayaka 比 Sachiyutaka 具有更高的叶水势和 TDM，但没有发现表明 Hatsusayaka 和 Sachiyutaka 之间在耐旱性上存在显着差异的证据。图形概要 粮食产量对灌溉水平的响应用线性高原模型近似，表明这些性状随灌溉量成比例增加，达到一定水平，之后达到阈值。我们的研究结果表明，在某些灌溉水平上，Hatsusayaka 比 Sachiyutaka 具有更高的叶水势和 TDM，但没有发现表明 Hatsusayaka 和 Sachiyutaka 之间在耐旱性上存在显着差异的证据。图形概要 粮食产量对灌溉水平的响应用线性高原模型近似，表明这些性状随灌溉量成比例增加，达到一定水平，之后达到阈值。我们的研究结果表明，在某些灌溉水平上，Hatsusayaka 比 Sachiyutaka 具有更高的叶水势和 TDM，但没有发现表明 Hatsusayaka 和 Sachiyutaka 之间在耐旱性上存在显着差异的证据。图形概要 但没有发现表明Hatsusayaka和Sachiyutaka在耐旱性上存在显着差异的证据。图形概要 但没有发现表明Hatsusayaka和Sachiyutaka在耐旱性上存在显着差异的证据。图形概要