Evaluation of cowpea for drought tolerance at seedling stage

Authors: RAVELOMBOLA, WALTRAM - University Of Arkansas; SHI, AINONG - University Of Arkansas; CHEN, SHENYU - University Of Minnesota; XIONG, HAIZHENG - University Of Arkansas; YANG, YUFANG - University Of Arkansas; CUI, QIRUI - University Of Arkansas; OLAOYE, DOTUM - University Of Arkansas; Mou, Beiquan

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2020
Publication Date: 7/12/2020
Citation: Ravelombola, W., Shi, A., Chen, S., Xiong, H., Yang, Y., Cui, Q., Olaoye, D., Mou, B. 2020. Evaluation of cowpea for drought tolerance at seedling stage. Euphytica. 216. Article 123. https://doi.org/10.1007/s10681-020-02660-4.
DOI: https://doi.org/10.1007/s10681-020-02660-4

Interpretive Summary: Cowpea [Vigna unguiculata (L.) Walp.,) is a human health promoting legume crop. The annual global cowpea production is 5.4 million tons of dry seed. Despite the fact that cowpea is one of the most drought-tolerant crops, some cultivars with high yield under sufficient water supplies have been reported to be highly drought-susceptible, thus still requiring the need for breeding drought-tolerant cowpea cultivars. We evaluated 331 cowpea varieties for drought tolerance at the seedling stage in order to identify sources of drought tolerance for development of drought tolerant, high yielding varieties. Drought tolerance assessments were done in a greenhouse using a previously described method and a total of 11 traits were assessed. The experiment was validated by the use of drought-tolerant and susceptible control cultivars. We found large variation in the evaluated traits for drought tolerance among the cowpea varieties. Many traits such as plant greenness and tolerance to trifoliate leaf chlorosis under drought stress were largely related, whereas no such relations were found for traits such as tolerance to trifoliate leaf chlorosis and unifoliate leaf chlorophyll content without drought stress. Twenty-one varieties were drought-tolerant, and country of origin was associated with drought tolerance in cowpea. The top performing varieties 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.

Technical Abstract: Cowpea is a health-promoting diploid legume species [Vigna unguiculata (L.) Walp., 2n=2x=22]. The annual global cowpea production is 5.4 million tons of dry seed. Although 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. The objectives of this study were to identify drought-tolerant cowpea genotypes at the seedling stage. We evaluated 331 cowpea genotypes in a greenhouse using a Randomized Complete Block design with three replications. Eleven traits were assessed using previously described methodology. The experiment was validated by the use of drought-tolerant and susceptible controls. There was significant (P0.05) variation in the putative 11 drought tolerance traits among the tested cowpea genotypes. Tolerance to trifoliate leaf chlorosis was significantly correlated (r=0.8, P0.05) with numerous traits, e.g., plant greenness, under drought stress, but was not correlated with various traits, e.g., unifoliate leaf SPAD chlorophyll, under non-drought stress. Twenty-one genotypes were drought-tolerant, and country of origin was associated with drought tolerance in cowpea. The top performing genotypes were repeated using an independent experiment to further validate the data. The results from this study is of interest to breeding programs aiming at improving drought tolerance in cowpea.