Morphological and productive aspects of lettuce in low altitude and latitude

Lettuce is considered a crop of mild climate and its production in regions of low altitude and latitude is impaired due to the high temperatures and the predominance of long days. Therefore, the aim of this study was to evaluate the behavior of lettuce cultivars in such conditions. An experiment was conducted at the Horta Didatica of the Federal University of Ceara, Campus do Pici, in Fortaleza. Nine lettuce cultivars from three commercial groups were used and distributed in a randomized block design, with four replications. The following qualitative traits were evaluated: bolting, head formation, leaf texture, anthocyanin and phytosanitary status for pest and disease infestation. Regarding the quantitative traits, plant height, plant diameter, fresh marketable weight (FMW), and non-marketable (FNMW) total fresh weight (TFW), dry marketable weight (DMW) and non-marketable (DNMW), total dry weight, chlorophyll a, chlorophyll b, chlorophyll a/b ratio. Data were submitted to analysis of variance and, later, grouping test was performed. None of the cultivars presented head formation but all presented early bolting. The cultivars showed no difference for FMW, however, Baba de Verao produced almost 72% more than Repolhuda Brasil from the same group. Regarding FMW, the most productive cultivars were Baba de Verao, Crespa para Verao, Americana Delicia, Crespa Repolhuda and Kaiser. However, Baba do Verao and Crespa stood out for DMW.