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

Abstract

OLIVEIRA, CAMILA SOARES. Genetic gain estimates by different selection criteria in tomato genotypes under water deficit. 2019. 30 p. Dissertation (Master Program Agronomy/Crop Science)-Federal University of Uberlândia. 1 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 1 st 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.

Recomendação da necessidade de irrigação para a cultura da soja utilizando parâmetros do balanço hídrico observados e ferramentas de simulação

“…Avaliando o comportamento estomático em plantas de mamoneira e algodoeiro em diferentes temperaturas (30 e 35ºC) Oliveira et al (2010) observaram que, as plantas de mamoneira conduzidas sob temperatura de 35 ºC apresentaram maior número de estômatos fechados e comportamento inverso no algodoeiro. O fechamento estomático é um importante mecanismo de defesa que as plantas apresentam contra perdas exageradas de água, que pode ter ocorrido nas plantas de soja em dias com temperatura extremas, acima de 35ºC (Figura 4).…”

“…Embora, com as diferenças entre valores realizados e simulados de irrigação para a cultura da soja neste ano agrícola com elevada restrição hídrica (Figura 6), é importante salientar que a modelagem do balanço hídrico contribui para maximizar a eficiência do uso da água, prevenir a escassez de recursos hídricos e minimizar os impactos ambientais (Assman;Oliveira, 2023). Inclusive Oliveira et al(2020) Mesmo o número de grãos por vagem ser um componente ligado diretamente a genética da cultivar conforme Mundstock;Thomas (2005), nota-se que a irrigação suplementar trouxe impactos positivos para a sua elevação (Tabela 3).…”