We evaluated the interaction genotype x environment of twelve genotypes of lettuce (Babá de Verão, Karla, Nacional, Elisa, Simpson, Hortência, Verônica, Grand Rapids, Laidy, Tainá, Lucy Brown and Raider), cultivated under greenhouse, low tunnel, low tunnel covered with black plastic screen, floating row cover (light-weight woven) and open field. All these treatments were conducted with and without mulching with ten treatments in total. The experiments were conducted in two different periods (August to November, 2001 and March to June, 2002). Each experiment (growth environment) was conducted using randomized blocks and three replicates. The measured variables were dry matter, volume and number of leaves. The value of F was significant (p<0,01) for the interaction genotype x environment. For the planting period from August to November/2001, the best results were obtained with the butterhead cultivars (Babá de Verão, Karla, Nacional, Elisa), cultivated under greenhouse with mulching, low tunnel without mulching and field without mulching. All cultivars had the worst performance when cultivated under tunnel with black plastic screen with or without mulching and floating row cover with or without mulching. For the planting period from March to June/2002, occurred a higher variability for all cultivars under studied environments. In this period, the cultivars of the butterhead group showed the best performance; the worst performance was observed for cultivars of crisphead group, in all environments. As observed for the planting period from August to November/2001, the superiority of butterhead cultivars group could be influenced by the number of leaves. Crisphead cultivars showed the worst results. However, these cultivars obtained the highest values of dry matter. When the goal of production is to obtain dry or fresh matter, the best option are the cultivars Laidy, Tainá, Lucy Brown and Raider, which showed the highest medias. When the final goal is the production of plants with bigger volume, the cultivars Simpson, Hortência, Verônica and Grand Rapids are the more adequate.
Lactuca sativa; growth system; cultivars
