The genus Vigna (Fabaceae) is an agriculturally important taxon, which includes several crop species such as cowpea (Vigna unguiculata L), mung bean (Vigna radiata) and azuki bean (Vigna angularis). Most studies have focused on cowpea (Vigna unguiculata (L.) as a drought-resistant crop, although insights on the mechanisms that confer this species the ability to grow in dry environment are still not fully resolved. The diversity of this rich genus has been overlooked in many physiological studies. This study explores the physiological mechanisms of response to soil drying (N2 fixation, transpiration rate and changes in C and N allocation) across three species of the Vigna genus: Vigna radiata, Vigna unguiculata, Vigna vexillata (tuber cowpea). A significant variability among the studied Vigna accessions was found for the threshold in decline of N2 fixation with soil drying. Less variability was observed in the transpiration threshold. Through the analysis of leaf traits variation under well-watered and water-deficit conditions, we were able to relate the variability in N2 fixation and transpiration response to C/N metabolism modifications resulting in different allocation of carbon and nitrogen to leaves under water deficit. This article is protected by copyright. All rights reserved.

中文翻译：

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三个未充分利用的豇豆属植物对土壤干燥的生理反应变化与 C/N 平衡关系的探索

豇豆属 (Fabaceae) 是一个重要的农业分类群，包括几种作物物种，如豇豆 (Vigna unguiculata L)、绿豆 (Vigna radiata) 和小豆 (Vigna angularis)。大多数研究都集中在豇豆（Vigna unguiculata (L.)）作为一种抗旱作物，尽管对赋予该物种在干旱环境中生长能力的机制的见解仍未完全解决。这个丰富的属的多样性已经被在许多生理研究中被忽视。本研究探讨了豇豆属三个物种对土壤干燥（N2 固定、蒸腾速率和 C 和 N 分配的变化）的生理机制：Vigna radiata、Vigna unguiculata、Vigna vexillata（块茎豇豆）。在所研究的豇豆种质之间发现了显着的变异性，因为土壤干燥导致 N2 固定下降的阈值。在蒸腾阈值中观察到较小的变异性。通过对水分充足和缺水条件下叶片性状变异的分析，我们能够将固氮和蒸腾响应的变异性与 C/N 代谢改变联系起来，导致缺水条件下碳和氮对叶片的不同分配。本文受版权保护。版权所有。我们能够将 N2 固定和蒸腾反应的可变性与 C/N 代谢改变联系起来，导致缺水情况下碳和氮对叶片的不同分配。本文受版权保护。版权所有。我们能够将 N2 固定和蒸腾反应的可变性与 C/N 代谢改变联系起来，导致缺水情况下碳和氮对叶片的不同分配。本文受版权保护。版权所有。