Linhagens de alface tropicalizadas com vantagens agronômicas e nutricionais

Abstract

Lettuce is one of the most important leafy vegetables cultivated worldwide. Stress due to high temperatures and lack of water has negative influences on the morphological, physiological and biochemical characteristics of plants, generating significant impacts on agricultural production and economic development. The presence of foods rich in carotenoids and chlorophylls is essential to prevent serious health problems. Efforts are needed to characterize new lettuce genotypes, allowing their cultivation under adverse conditions in a sustainable manner. The objective of this study was to characterize tropicalized lettuce lines regarding their agronomic and nutritional advantages. Eighteen lettuce lines and two commercial cultivars as controls (cv. Belíssima and Grand Rapids) were evaluated for chlorophyll and carotenoid contents, agronomic parameters, gas exchange, chlorophyll a fluorescence, oxidative damage and antioxidant enzyme activity. The experimental design was randomized blocks with 20 treatments and four replicates. The data were subjected to analysis of variance using the F test (p < 0.05). The means were compared using the Scott-Knott test (p < 0.05) and submitted to multivariate analysis represented by the dendrogram obtained by the hierarchical method Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA). A self-organizing Kohonen map (SOM) was generated to compare the genotypes according to the variations observed. Lines with high levels of chlorophylls, carotenoids, late tasseling, agronomic potential, reduced transpiration rate, better stomatal control, intrinsic water use efficiency, photosynthetic apparatus efficiency and reduced oxidative stress were found. It was possible to characterize green and purple biofortified lettuces with genetic potential for expression of biochemical and physiological characteristics that allow their adaptation to tropical environments.