This research was conducted to determine the effects of different salinity levels of nutrient solution on tomato plants grown in an open system substrate culture during autumn and spring seasons of 2000 and 2001. The seedlings were planted in the horizontal pots filled with perlite (8 liters per plant). Plants were fed with a complete nutrient solution at the electrical conductivity levels of (T2) 2.0 dS.m(-1) (control), (T6) 6.0 dS.m(-1) and (T2+T6) half day 2.0 and half day 6.0 dS.m(-1). In the spring season, a fourth treatment was added as half day 2 and half day 6 dS.m(-1) + foliar Ca sprays at two weeks intervals. The results showed that fruit yield and water consumption of tomato plants decreased dramatically with the increase of salinity. The highest yield was obtained from the control treatment in both seasons (13.6 kg.m(-2) in autumn, 14.3 m(-2) in spring). Compared to the control treatment (T2), the yield decreases were 28 and 37% at T6 treatment in autumn and spring seasons, respectively. Ca sprays didn't affect the yield significantly, but reduced the incidence of BER fruit. On the other hand, increasing EC levels in the nutrient solution improved the taste and quality of fruits by increasing the total dry matter content of fruits and total soluble solids and titratable acidity contents of the fruit juice.