Estimativas de ganho genético por diferentes critérios de seleção em genótipos de tomateiro sob deficiência hídrica

Abstract

Tomato crops require high amounts of water and are negatively affected when submitted to water restriction conditions. This may be minimized by using the introgression of genes responsible for controlling the tolerance to water deficits. However, the characteristics related to this type of tolerance are highly complex, which limits selection inferences. The use of selection indexes may be an efficient tool to select genotypes that are more tolerant. This research aims to assess selection indexes based on the estimated genetic gains, as well as to select tomato plant genotypes after they have been submitted to conditions of water deficit through different selection criteria. The research took place at the Horticultural Experiment Station of the Federal University of Uberlandia and was conducted in Random Block Design (RBD) with three repetitions. We used seven genotypes from the interspecific cross between S. pennellii vs UFU-040, Solanum pennelli the donor parent, UFU-040 the recurrent parent and the cv. Santa Clara, totaling ten treatments. Plants were submitted to a moderate water deficit with a matric potential of -34 kPa. We analyzed foliar temperature, the SPAD index, leaf water potential, amount of fruits produced per plant, average fruit weight, yield per plant, incidence of apical rotting, dry matter of the aerial part percentage, root and total, amount of leaves, plant height, and distance of 1st bunch relative to the substrate. In sequence, analysis of variance, Scott-Knott’s and Dunnett’s tests for comparison of means, genotypes’ relative superiority tests and analysis of selection indexes were performed. The genitor donor, wild accession S. pennellii, was indeed tolerant to water deficit and the Santa Clara cultivar was sensitive to water restriction. This fact reinforces the wild accession’s genetic potential of S. pennellii for introgression of genes that promote water deficit tolerance. The T5 genotype presented agronomic potential and satisfactory levels of water deficit tolerance, and it was 58,2% higher in production than the pre-commercial lineage and the UFU-040 recurrent parent. The ideotype-genotype distance selection index is the most appropriate for selection of tomato plant genotypes submitted to water deficit.