Optimisation of Off-Soil Tomato Fertilization and Substrate Recipes

Substrate and fertilizers recipes and their balances are two factors affecting the growth of hydroponic crops. However, the responses of crop cultivars to different substrate and fertilizer are less clear. This study was aimed at assessing the different responses of tomato (Solanum Lycopersicum L.) cultivars to the different substrate and fertilizer supply. The study was carried out at the Centre de Recherche et de Formation Agricole (CRFA) of the Lebanese University to test three types of substrates; S1 (100% coconut fiber), S2 (50% coconut fiber and 50% grape marc) and S3 (25% coconut fiber and 75% grape marc). As well as three fertilization recipes; F1 (ARTC), F2 (University of Arizona) and F3 (Farmer) were applied in order to be able to recommend the best substrates and fertilizers adapted to the conditions of cultivation off-soil. The production cycle was divided into three phases; phase1 (0-6 weeks), phase2 (6-12 weeks) and phase3 (> 12 weeks). Various parameters were measured throughout the cycle; stem length, number and distance between nodes, number and distance between flower buds, and fruit yield. Results for stem length and number of nodes showed good interaction in favor of F2-S1 throughout the cycle. As far as the distance between nodes is concerned, F1 is the best despite the fact that F2 is more economical and S1 showed a superiority. The number of flower buds is positively affected by F1 and F2 and S1 and S3. As far as the distance between floral buds is concerned, F1 and F2 are the best, F2 is the most profitable and S2 played a favorable role in the distance between floral buds. The number of fruits is in favor of F1 and F2, S1 is the best. In terms of plant yield, F2 is the most favorable and S2 is the best. After that, F2 is the best recipe and F1 is the most economical. S1 and S2 did well in the development of the tomato plant by their proper physico-chemical properties. S1 is slightly better.