YIELD, WATER USE AND NUTRIENT UPTAKE OF A TOMATO CROP GROWN ON COCONUT COIR DUST

An experiment was designed to determine the yield, water use and nutrient uptake of a tomato (Lycopersicon esculentum Mill. cv. Rambo) crop grown on coconut dust substrate using fertigation, without re-utilization of drained nutrient solution. The density was 2 plants m^-2, with 11 litres of substrate per plant. The total yield was 19.9 kg m^-2, the marketable yield 15.9 kg m^-2 and the average marketable fruit weight 210.2 g. The total nutrient solution provided during growth period was 736.8 mm, the drainage loss came to 219.4 mm and, thus, the crop water use average 517.4 mm. In the growth period, the irrigation frequency varied from 3, at the beginning of growth, to 14 irrigations per day, during the period of maximum water requirement, the amount of water changing from 0.3 to 6.6 mm per day. The drainage losses fluctuated between 18% and 30.5%, and the electric conductivity between 3 and 6 dS m^-1. Nutrient uptake by the crop (in g.m^-2) was: 65.1 N, 27.7 P, 97.3 K, 54.1 Ca, 18.6 Mg and 24.8 S.