An experiment was carried out at the Experimental Farm, of Marília University, from September 23th 1997 to November 21st 1997 with the objective of evaluating the performance of six butterhead lettuce cultivars (Babá de Verão, Brasil 303, Elisa, Karla, Lívia and Monalisa) in three spacings (25 x 20, 25 x 25 and 25 x 30 cm), cultivated under a hydroponic system 'NFT'. Stem length, fresh matter yield per plant and per area, and aerial part and root dry matter weight were evaluated. The Experiment was laid out as a 6 x 3 factorial randomised block design with three replications per treatment. No considerable effect on yield was found in the interaction between cultivars and spacing. Cultivars Babá de Verão, Lívia and Elisa stood out in terms of total fresh and dry matter weight. Cultivars Monalisa and Karla showed less susceptibility to bolting, and 'Babá de Verão' the greatest susceptibility. Spacing did not have any significant influence on the characteristics studied, with the exception of yield per area. Independent of cultivar, the highest marketable yield (4.465 Kg/m²) was obtained with the spacing 25 x 20 cm, with significantly lower yields measured in the 25 x 25 cm and 25 x 30 cm treatments: 3.583 and 3.304 Kg/m², respectively, due to a reduction in the number of plants per square meter.
Lactuca sativa; culture technique; hydroponic; butterhead lettuce
