GROWTH, PRODUCTIVITY, AND MINERAL-COMPOSITION OF HYDROPONICALLY CULTIVATED GREENHOUSE TOMATOES, WITH OR WITHOUT NUTRIENT SOLUTION RECYCLING

Tomato plants (Lycopersicon esculentum Mill, cv, Capello) were grown i n the three most promising and used hydroponic cultivation systems usi ng rockwool and peatmoss substrates and nutrient film technique (NFT), either with or without recovery and recycling of the drainage solutio ns, Prolonged recycling of nutrient solutions in NFT caused a reductio n in fresh weight, dry weight, and yield compared to plants grown in N FT with regular renewal of the nutrient solution, There were no differ ences in growth, productivity, and leaf mineral composition between pl ants grown in rockwool and peatmoss systems, with or without recycling , and in the NFT system without recycling These results suggest that r ecycling drainage solutions is an economically and environmentally sou nd horticultural practice that when used correctly does not cause a re duction in yield of tomatoes cultivated in rockwool or peatmoss. Howev er, prolonged use of the same solution in the NPT cultivation system c an negatively affect growth and yield. This is most likely due to an a ccumulation of sulfate ions in the fertigation solutions.