Screening for Drought Tolerance in Tepary and Common Bean Based on Osmotic Potential Assays

Common bean (Phaseolus vulgaris L.) is the most important food legume grown worldwide. In Mexico, it is a strategic crop, occupying the second place in terms of cultivated area. Drought is the main problem for common bean production in Mexico. Some tepary (Phaseolus acutifolius A. Gray) and common bean genotypes can be a source for drought tolerance to improve commercial cultivars. The main objectives of this study were the evaluation of germination and seedling growth components in response to drought stress and the identification of sources of drought tolerance in both tepary and common bean. The experiment was conducted using various osmotic pressures (OP) induced by polyethylene glycol (PEG6000) (0, -0.15, -0.30 and -0.49 MPa) simulating an increase of drought stress in seven common bean and three tepary bean genotypes. The most drought-tolerant genotypes were two tepary beans: Tepary cafe which had a reduced root length of 21.4% and Tepary negro that decrease root length in a 29.7% compared to control at high osmotic pressure. Besides, two common beans: Rosa Bufa and Santa Fe (which decreased root length at high osmotic pressure in 46.0% and 34.2%, respectively) could be used as sources of favorable alleles to improve bean tolerance to drought. There are different strategies to tolerate drought, such as developing a long root, root fresh weight, and root dry weight