SOILLESS CULTURE TECHNOLOGY FOR HIGH QUALITY LETTUCE

The aim of this research was to evaluate butterhead lettuce quality in a soilless culture system. Butterhead lettuce cultivar “Lores” was cultivated, and two experiments were performed. In the first, floating system (FS) and soil culture (SC) were compared in fall (autumn) prduction [2002 - 2003], while in the second, substrate culture (PC) (plastic gutter filled with perlite) with three different levels of calcium (0, 3, and 6 me L^-1) in the nutrient solution were compared in spring production [2003]. Growing cycles varied according to the culture system. In general, plants harvested from the soilless culture had a lower dry weight and leaf area, however significant differences were observed in productivity. Nitrate content was significantly affected by the production system. Ascorbic acid content showed no differences resulting from treatments. Floating system results showed some variation between the two years of the experiment. Inorganic cation differences were observed between plant harvest from all systems, especially in K⁺ and Mg²⁺. Colour intensity changes between production systems were insignificant. No variation in incidence of tip-burn relating to different calcium levels was found in lettuce grown in perlite.