Biochemical, physiological and phenological genetic analysis in common bean (Phaseolus vulgaris L.) under salt stress

Salinity is one of the most important abiotic stresses affecting agricultural productivity. The present study investigated combining abilities, heterosis and heritability estimates of common bean under salinity conditions for biochemical, physiological and phenological traits using a half-diallel cross. The salinity stress treatments were applied during all the vegetative cycle. Genetic analysis revealed highly significant genotypic variations between the four parents and their six hybrids, indicating a genetic variability and possibility of genetic improvement using such genetic material of common bean for salinity tolerance. Both general (GCA) and specific (SCA) combining abilities were highly significant for all the studied traits under all conditions, revealing the important role of both additive and dominant gene effects in the inheritance of these traits. The ratio GCA/SCA indicated preponderance of the additive effects for all the studied characters. The parental genotypes Ameliore Roza and Coco nain proved to be the best combiners for salinity tolerance; on the other hand the crosses namely Amina x Ameliore Roza; MGT x Ameliore Roza and Coco nain x Amina recorded significant heterosis percentage relative to mid-parent (MP) and better parent (BP) for almost all the traits, the same crosses recorded significantly positive SCA effects. Diallel analysis revealed high heritability in broad-sense for salinity tolerance, while moderate to high narrow-sense heritability suggests a large breeding population and possible selection for salt tolerance. The results of this study confirmed that salinity tolerance is expressed by a different set of genes that could be pyramided using different genotypes to enhance salinity tolerance.