ZEOLITES IN MEDIA MIXES FOR SOILLESS PRODUCTION: FIRST RESULTS ON TOMATO

Growing media are an essential part of any hydroponic system and they influence crop management, irrigation schedule, and nutrients uptake. The present work aims at assessing the beneficial effects of adding zeolite either to perlite or to coconut fiber media on the performances of three cultivars of tomato (‘Idoll’, ‘Grandella’, ‘Secolo’). Plants were grown during summer 2008 in a commercial hydroponic greenhouse in North Italy using rockwool (Grodan®), coconut fiber, perlite, mixed coconut fiber and zeolite (70/30 v/v), and mixed perlite and zeolite (70/30 v/v). Irrigation schedule and nutrient solution were managed according to Grodan® guidelines. During the whole cycle, plant growth and development (plant height, blossoming, fruit setting, and leaf number) were monitored, and Yara N-Tester readings were collected weekly starting from 30 days after transplanting (DAT). At harvest both commercial and waste fruit were counted and weighted. Data showed more constant N-Tester values for rockwool, whilst zeolites seemed to reduce both higher and lower readings peaks if added to coconut fiber or perlite. Biometrics and phenological observation were strongly influenced by cultivars, with no significant interaction with growing media. Zeolites mixed with coconut fiber improved ‘Grandella’ production whilst it had no effect on ‘Secolo’ and ‘Idoll’, the latter one performed better on the perlite-zeolite mixture than perlite whilst there was no statistical difference for the other two cultivars. No effects were attributable to growing media concerning the percentage of waste fruit.