Morphological Attributes and Metabolites of Seedlings in the Selection of Melon Genotypes Under Water Deficit
The selection of genotypes with greater tolerance to water scarcity during the early stages of growth can be a promising strategy for genetic improvement, as it enables early screening and may accelerate the identification and selection of tolerant genotypes under field conditions. Therefore, the objective of this study was to evaluate initial seedling growth, metabolic responses, and the selection of melon genotypes under water-deficit conditions. For this purpose, seeds from twenty genotypes were subjected to two osmotic potentials induced by PEG 6000 (0.0 and −0.25 MPa), with four replicates in a completely randomized design. The variables analyzed were germination percentage, germination speed index, shoot and root length, shoot and root dry mass, total dry mass, drought tolerance coefficient, and concentrations of amino acids, total sugars, and proline. Univariate and multivariate analyses of variance were performed, and genotypes were grouped using the Scott–Knott method. Genotype classification was based on the estimated drought tolerance coefficient, which was also evaluated using the membership function value. A water deficit of −0.25 MPa negatively affected germination speed and percentage, root length, and shoot dry mass, whereas metabolites exhibited the opposite behavior. Genotypes I-136 and PI234607 were classified as drought-tolerant, genotypes A-50 and A-52 as susceptible, and genotypes A-08 and A-09 as highly susceptible.