Inheritance of Drought Tolerance in a F3 Biparental Population of Pinto Saltillo (Phaseolus vulgaris L.) × Tepary Cafe (Phaseolus acutifolius A. Gray)

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Drought is the most significant negative factor affecting common bean (Phaseolus vulgaris L.) production. Scarce studies about the genetic control of drought tolerance in beans impedes a more effective exploitation of these traits in plant breeding. The Tepary bean (Phaseolus acitifolius A. Gray) is considered a valuable source of drought-resistant genes for improving commercial varieties that are susceptible to drought. The main objective of this study was to evaluate the germination and seedling growth components in response to drought stress simulated with polyethylene glycol (PEG-6000). We developed a F3 biparental population from the cross between the susceptible P-saltillo variety and drought-tolerant T-cafe, which allowed the study of drought-tolerance genetics in beans. The F3 biparental population showed wide variability for the traits studied, i.e., from 0.0 to 2.4 for hypocotyl length, from 0.3 to 3.9 and 7.5 to 97.5 for germinated seeds (n and % hypocotyls, respectively), from 0.3 to 3.9 and 7.5 to 97.5 for germinated seeds (n and % roots, respectively), from 0.3 to 4.5 for root length, and from 0.0 to 4.8 for total length. The heritabilities for hypocotyl length (cm), germinated seeds (n hypocotyl), germinated seeds (% hypocotyl), root length (cm), germinated seeds (n roots), and germinated seeds (% roots) were moderate from 0.32 to 0.47. The heritability for root length was low with a value of 0.20. The most important positive and significant genetic correlations (0.80) were found between the hypocotyl length (cm) and root length, which means that the longer the hypocotyls, the longer the root. All variables studied have normal distribution, which is why they are considered quantitative inheritance. The results highlight lines that can be candidates for the registration of new drought-tolerant varieties or used as sources of drought tolerance in future common bean improvement programs. Our results indicate that multiple genetic factors are involved in the drought tolerance response of the F3.