Resumo

SOUZA, Maria da Conceição M de et al. Genetic variability for agronomic characteristics in lettuce progenies with heat tolerance. Hortic. Bras. [online]. 2008, vol.26, n.3, pp. 354-358. ISSN 0102-0536.  http://dx.doi.org/10.1590/S0102-05362008000300012.

Lettuce progenies with tolerance to early bolting were evaluated in relation to commercially desirable agronomic characters, as well as to estimate important genetic components for crop breeding. The experimental design was random blocks with three replications and 18 treatments (13 progenies F₇, the genitors Verdinha, Regina, and Tinto, and cultivars Luisa and Babá de Verão). The genetic, phenotypic, and environmental variances, the heritability, and the correlation among the characters number of leaves, plant and leaves fresh weight, plant diameter, stem length, and bolting, were estimated. The F test was significant (p<0,01) for all the studied characteristics. In the clustering of means by the Scott-Knott test, at 5% probability, treatments were assembled in two groups, except for plant diameter, in which cultivar Tinto remained isolated in a third group. The genetic variance was higher than the environmental variance for all evaluated characteristics, and the heritability, below 90%, revealed the environmental influence over some characters. When bolting was correlated to the other characteristics, results were positive and significant for most combinations, considering the genetic correlations. Under these experimental conditions, progeny 76 stood out for its low stem length and reduced bolting index, although its commercial performance was inferior to the control cultivars, genitors, and some other progenies.

Palavras-chave : Lactuca sativa L.; bolting; heritability; genetic correlations.