The objective of this study was to estimate the adaptability and phenotypic stability of cultivars of crisp lettuce in different growing seasons and under high-temperature conditions. The experimental design used was of randomized blocks in a 5 x 7 x 2 factorial scheme, consisting of five cultivars (Veronica, Vera, Cinderella, Isabela and Veneranda), seven environments (open field, 30, 40 and 50% shading, and 30, 40 and 50% heat-reflective mesh), and two cropping seasons (October-December 2008 and July-September 2009) with four replications. In respect to both total and commercial production, the cultivar "Veronica" was that which most stood out. There were differences in yield performance of the cultivars in relation to the cropping seasons. The parameters, coefficient of determination and index of variation of the number of leaves, are close to one, showing greater stability. The cultivar "Veronica" remained more stable during periods of production, with a better response to the growing season, regardless of the environment. The cultivar "Cinderella", compared to the other cultivars, maintained good yield, being the second choice for farming.
Lactuva sativa; Crops yield; Interaction genotype and environment
