Impact of soil moisture stress on growth and physiological traits of tepary bean genotypes

Background: In South Africa, tepary bean is cultivated by smallholder growers, mainly in the Sekhukhune District (Limpopo province), which is prone to drought. Currently, there are no significant breeding efforts aimed at cultivar selection and crop development, and the crop remains underutilised despite its potential value. Aim: To evaluate diverse tepary bean collections using physiological and growth attributes. Setting: Agricultural Research Council – Vegetable, Industrial and Medicinal Plants, South Africa in drought screening glasshouse. Methods: A 6 × 7 rectangular lattice experimental design was replicated three times. Results: Results showed that there were significant (p < 0.05) differences among the tepary bean collections tested for all the selected traits that were measured. The highest (1.05 µmoL/g dry weight) and lowest (0.32 µmoL/g dry weight) leaf proline contents were observed for genotypes ‘Ac-35’ and ‘Ac-9’, respectively. The genotype ‘Ac-33’ achieved almost twofold higher relative water content (84.72%) than the rest of the accessions tested. Conclusion: The current study was conducted in a greenhouse as a rapid method to determine the differences in response to drought among several tepary bean genotypes. The genotypes showed a wide range of variability for all the trait attributes that were considered before and after soil moisture stress. The principal component analysis revealed three distinct genotypes (‘Ac-6’, ‘Ac-13’ and ‘Ac-31’) under the moisture stress regime that can be considered for further investigation, particularly under field conditions to determine their grain yield potential. There would be merit in conducting further studies to determine the yield potential of the genotypes selected in this study in multiple field-testing locations. Contribution: There would be merit in conducting further studies to determine the yield potential of the genotypes selected in this study in multiple field-testing locations.