Teores de clorofila e β-caroteno em cultivares e linhagens de alface

Abstract

Vitamin A is a nutrient that is found only in animal foods, as vegetables provide provitamins A such as beta and alpha-carotene and beta-cryptoxanthin, which may be biologically transformed into vitamin A in animal organisms. Among the most consumed vegetables, lettuce can be an important source of vitamin A from the selection of cultivars with higher levels of beta-carotene in the leaves. In this study we evaluated 18 cultivars of lettuce types of American, crisp and smooth, and 8 strains derived from a cross between a cultivar of American type (Salinas 88) and another of plain sheets (Regina 71), for concentrations of chlorophyll, beta-carotene and staining characteristics of the leaves, with the objective of verifying the existence of genetic variability, the possibility of existence of correlations between the characteristics and potential use of lettuce cultivars to obtain new strains with higher levels of beta-carotene. The experiment was conducted in greenhouse using a randomized block design with three replications and six plants per plot. At the time of commercial harvest plants were evaluated for their leaf chlorophyll content using the SPAD. While leaf samples were collected and taken to the laboratory for analysis of the levels of beta-carotene using CLAE, as also subjected to analysis for staining. There were significant differences for all traits, indicating the existence of genetic variability among cultivars and strains, and the broad-sense heritability greater than 0.80 for all traits, indicating the possibility of genetic gains from selection in plant populations segregating for the traits considered. The lines, as well as the American type cultivars showed levels of chlorophyll and beta-carotene higher than those of type cultivars crisp and smooth, indicating potential use of American-type cultivars to obtain cultivars with higher levels of beta-carotene. The correlation between levels of beta-carotene and chlorophyll was about 0.82, suggesting the possibility of success of indirect selection for high levels of beta-carotene using the SPAD reading as direct selection of plants with high content of chlorophyll.