Genetic parameters of drought tolerance for agromorphological traits in eggplant, wild relatives, and interspecific hybrids

Crop wild relatives (CWRs) have barely been used in eggplant (Solanum melongena) breeding. However, introgression breeding may help in coping with the challenges posed by climate change. During the rainy and dry seasons, we evaluated nine accessions of eggplant, nine accessions of seven related species (of which six are CWRs and one is a cultivated relative), and 12 interspecific hybrids. Drought tolerance scores, calculated as ratios of growing rates and ratios of mean values during the rainy and dry seasons, were obtained for vegetative growth and yield‐related traits. Considering the vegetative growth and yield‐related traits evaluated, the F1 hybrid progenies of eggplant with S. insanum MEL1 × INS2 and MEL4 × INS3, S. anguivi MEL6 × ANG1, and S. dasyphyllum MEL6 × DAS1, plus the S. sysimbriifolium accession SIS1, displayed drought tolerance. Small to large gaps were observed between phenotypic and genotypic CVs of drought tolerance scores, reflecting variable influence of environmental factors on drought tolerance of the traits evaluated. In addition, the narrow‐sense heritability was generally moderate, indicating that genes with dominance and/or epistasis effects may be involved in the expression of drought tolerance. High genotypic correlations for drought tolerance scores between pairs of traits such as branching index and leaf length, leaf petiole diameter and plant height, number of stamens per flower, and fruit pedicel length suggest that drought tolerance of these traits is controlled by genes that are in linkage disequilibrium and/or have pleiotropic effects. The results are relevant for the development of drought‐tolerant cultivars of eggplant.