WATER-USE AND YIELD OF GREENHOUSE-GROWN EGGPLANT UNDER DRIP IRRIGATION

The water consumptive use of eggplant, hyb. Delica, grown in unheated greenhouse was determined using tensiometers. The maximum evapotranspiration (ET(m)), when soil water potential was maintained at values higher than -20 KPa, ranged from 0.5 to 4.5 mm day(-1), with a whole season irrigation requirement corresponding to 380 mm. Water amount equal to 0.85 X ET(m) had no effect on fruit yield, which was 6.5 kg per plant; water application of 0.65 X ET(m) and 0.40 X ET(m) reduced total yield by 35% and 46%, respectively. Fruit number per plant was significantly reduced at 0.65 X ET(m) and 0.40 X ET(m), while fruit size was not affected by the amount of water applied. The crop ET(m) in October (at planting) was 0.2 of A pan evaporation (E(pan)) located outside the greenhouse. This value remained constant until February and then increased gradually to 0.8 X E(pan) at the end of the experiment, in May. Salt content was higher at the surface 10 cm soil layer with all amounts of water applied. With 1.00 X ET(m) and 0.85 X ET(m) salts were leached out of root zone, while an additional amount of water was required at 0.65 and 0.40 X ET(m) for salt leaching.