Adaptability and phenotypic stability of crisp lettuce cultivars in hydroponics

Considering the climatic seasons in which lettuce is cultivated, probably a high interaction genotype x environment could be obtained. The yield, adaptability and phenotypic stability of six lettuce cultivars of the crisp group (Deyse, Elba, Sabrina, Summer Green, Vera and veronica) were evaluated, on hydroponic 'NFT'. Nine experiments were carried out in three seasons (autumn(-) Out(n), winter= Inv(n) and spring= Pri(n)), in a completely randomized design with four replications, evaluating four plants in each treatment. There occurred significant differences among environments (Sowing date). Planting in autumn presented higher yield (Out(1) = 3,1: Out(2) = 5.3 and; Out(3) = 4,6 kg m(2)) than winter (Inv(1) = 3.6; Inv(2) = 3,5 and; Inv = 3,7 kg m(2)) or spring (Pri(1) = 4,0; Pri(2) = 3,6 and; Pri(3) = 3,2 kg m(2)). Although the significant differences in the interaction cultivars x environment for yield, except for Inv(3) and Pri(1), there were no significant differences among cultivars in each planting season. Significant differences were found among cultivars only in Out(3) for the number of leaves in each plant. Cultivars Deyse and Veronica were the only ones well adapted in both environments for yield, the other cultivars being unstable. Only Summer Green presented behavior highly previsible (stable) for number of leaves per plant, nevertheless, showed adaptability only in unfavourable environments.