Estimativas de parâmetros genéticos para pigmentos foliares e caracteres agronômicos em diferentes populações de alface.

Abstract

The knowledge about the nature and magnitude of gene effects that govern certain characteristic are, are essential for the guidance and choice of the best method of selection in early generations and advanced lettuce (Lactuca sativa). The present study aimed to investigate the genetic bases responsible for the expression of leaf pigments and agronomic characters in lettuce. The study was carried out from February 2017 to June 2018 at the Horticultural Experiment Station of the Federal University of Uberlândia (UFU), Monte Carmelo Campus, state of Minas Gerais. The parentals P1 and P2 and generations F1, F2, and backcrosses Bc1 and Bc2 were evaluated in field conditions in a randomized genetic analysis of generations. It is estimated genetic parameters: variances phenotypic, genotypic, environmental, additive and dominance; in the broad sense heritability and narrow sense; average degree of dominance and minimum number of genes involved in the expression of the characteristics: chlorophyll content, anthocyanin content, leaf number and diameter of plants. The chlorophyll content of lettuce genotypes was significantly influenced by the environment, while the remaining characteristics presented greater influence of genotypic factors in the phenotype. For the features number of leaves and plant diameter there was a greater proportion of the additive genetic variance in the expression of the phenotype. The coefficients of heritability in the narrow sense were considered high or medium for number of leaves and high for the anthocyanin content. All characteristics proved to be polygenic in nature. The main genetic parameters (m, a and d), explains mostly the behavior observed in the F2 generation.