2nd Balkan Symposium on Vegetables and Potatoes -- OCT 11-15, 2000 -- THESSALONIKI, GREECEWOS: 000177999500103In this research, three variables: nutrition system, substrate and irrigation schedule, were tested. The nutrient solution was supplied in closed or open systems. The substrates were volcanic tuff, perlite, perlite+peat (3:1, v/v) and perlite+peat (1:1, v/v), and irrigation was scheduled based on indoor solar radiation levels of 1.0, 2.0, 3.0 and 4.0 MJ/m(2). The closed system gave yields as high as in the open system without quality loss, and reduced the amount of wasted water by up to 3.4 times compared to the open system. Perlite and volcanic tuff gave higher yields than perlite and peat mixtures. It is recommended that tomato plants should be grown in volcanic tuff or perlite in a closed system with irrigation provided at an indoor solar radiation level of 1 MJ/m(2).Hellen Minist Agr, N AG RE F Agr Res Ctr Macedonia & Thrace, Minist Macedonia & Thrace, Afg Bank Greece, Hellen Sugar Indu S A, Elga, Bios AgrSyst, Municipal Thermi, Geotherm Greenhouses - Equipment, Scientact S A, Rockwool Grodan MED S A, Plastika Kritis, Psyllakis Nikolaos, Ypsilon, Rigas Labs, Agribous, Asteriadis S A, Ferror Plas
