Cowpea is a health-promoting diploid legume species [ Vigna unguiculata (L.) Walp., 2 n = 2 x = 22]. The annual cowpea production is 5.4 million tons of dry seed globally. Despite the fact that cowpea is one of the most drought-tolerant crops, some genotypes with excellent agronomic traits such as high yield under sufficient water supplies have been reported to be highly drought-susceptible, thus still requiring the need for breeding drought-tolerant cowpea genotypes. Therefore, the objectives of this study were to evaluate drought tolerance in cowpea at seedling stage and to identify drought-tolerant cowpea genotypes. In this study, a total of 331 cowpea genotypes were evaluated for drought tolerance at seedling stage. The experiment was conducted in a greenhouse and repeated 3 times. Drought tolerance phenotyping was conducted using a previously described methodology and a total of 11 traits were analyzed. The experiment was validated by the use of drought-tolerant and susceptible controls. Results showed that: (1) a large variation in the evaluated traits for drought tolerance was identified among the 331 cowpea genotypes, (2) a high correlation was found for traits such as plant greenness score and tolerance to trifoliate leaf chlorosis under drought stress ( r = 0.8), whereas no linear correlation was found for traits such as tolerance to trifoliate leaf chlorosis and unifoliate leaf SPAD chlorophyll under non-drought stress ( r = 0.0), (3) a total of 21 genotypes were found to be drought-tolerant across different traits, and (4) country of origins could impact drought tolerance in cowpea. The top performing genotypes were repeated using an independent experiment to further validate the data. The results from this study would be of interest in breeding programs aiming at improving drought tolerance in cowpea.

中文翻译：

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豇豆苗期耐旱性评价

豇豆是一种促进健康的二倍体豆科植物 [Vigna unguiculata (L.) Walp., 2 n = 2 x = 22]。全球每年豇豆产量为 540 万吨干种子。尽管豇豆是最耐旱的作物之一，但据报道，一些具有优良农艺性状（如在充足水分供应下产量高）的基因型具有高度干旱敏感性，因此仍需要培育抗旱豇豆基因型。因此，本研究的目的是评估豇豆幼苗期的耐旱性并鉴定耐旱豇豆基因型。在这项研究中，共评估了 331 个豇豆基因型在苗期的耐旱性。实验在温室中进行，重复3次。使用先前描述的方法进行耐旱表型分析，并分析了总共 11 个性状。该实验通过使用耐旱和易感对照进行验证。结果表明：（1）在331个豇豆基因型中鉴定出耐旱性状差异较大，（2）在干旱胁迫下植物绿度评分和对三叶黄萎病的耐受性等性状具有高度相关性。 r = 0.8），而在非干旱胁迫下对三叶叶萎黄病和单叶叶SPAD叶绿素的耐受性等性状未发现线性相关（r = 0.0），（3）共发现21个基因型是干旱的-对不同性状的耐受性，以及 (4) 原产国可能会影响豇豆的耐旱性。使用独立实验重复表现最佳的基因型以进一步验证数据。这项研究的结果将对旨在提高豇豆耐旱性的育种计划感兴趣。