Técnicas multivariadas na determinação da diversidade genética de genótipos de tomateiro submetidos ao déficit hídrico

Abstract

Tomato is a vegetable grown worldwide, and one of its characteristics is its high water demand, which is negatively affected when subjected to a water restriction condition. Due to the fact that the characteristics related to this type of tolerance are highly complex, studies on the characterization of tomato germplasm aiming at tolerance to this abiotic stress are scarce. Therefore, the objective of this work was to evaluate the genetic dissimilarity in tomato germplasm with different levels of tolerance to water deficit. The experiment was carried out at the Experimental Station of Vegetables at UFU in DBC with three replications. Seven genotypes from the interspecific cross between S. pennellii vs UFU-040, the donor parent Solanum pennelli, the recurrent parent UFU-040 and cv. Santa Clara, totaling ten treatments. Plants were subjected to moderate water deficit, whose matric potential was ≥ 25 kPa. Leaf temperature, SPAD index, leaf water water potential, number of fruits per plant, average fruit weight, production per plant, incidence of apical rot, percentage of shoot, root and total dry matter, number of leaves were evaluated. , height of plant and distance of insertion of the first bunch in relation to the substrate and length of internodes. The genetic dissimilarity of the genotypes was obtained by the generalized Mahalanobis distance and represented by different clustering methods. Tocher's method was the least efficient in distinguishing the genotypes forming two groups. The UPGMA and Canonical Variables method showed greater discriminative power, both forming three similar groups. Multivariate analyzes were efficient in representing the genetic diversity existing among the 10 evaluated genotypes. The F2RC3 populations can be considered promising for the tomato breeding program aiming at tolerance to water deficit.