Abstract

Few studies have been published on nutritional parameters in greenhouse cultivated watermelon despite the importance of this species in the human diet. It was therefore considered worthwhile to study some of the cultivars soon to become commercially available in Spain to determine which of them are best suited to cultivation in areas along the Mediterranean coast. All ten cultivars of Citrullus lanatus (Trunb) Mansfield studied were grown in polyethylene covered greenhouses. Four replications of each cultivar distributed in random blocks. Leaves were sampled every 15 days during one complete biological cycle to determine total macro- and micro-nutrients. These data ere then related to productivity (fruit yield). The different cultivars presented marked differences in both macro- and micronutrient levels: total N in Perla-Negra (Black Pearl) was twice that found in Tolerant, while total K in Resistent was double that in Candida. Total proteins also differed significantly between cultivarss as did productivity. All high yielding cultivars grown in greenhouse conditions showed high but varying nutritional requirements, with different optimal ranges of total nutrients. Upon comparing nutritional needs and productivity, efficiency in descending order was Perla-Negra, Panonia, Tolerant, Candida, Sugar-Baby, Rocio, Fabiola, Carmit, Early-Star, and Resistent. On the basis of nutritional diagnosis, nutrient values were classified as low, optimal and high, in relation to productivity and total nutrient levels. Important information concerning the responses of cultivars to salinity under various saline water concentrations was obtained by tissue analysis. It should be kept in mind that this information may also be influence by plant species and enviromental conditions.