Effect of drip or subirrigation on growth and yield of Solanum melongena L. in closed systems with salty water

The study was aimed at evaluating the response of eggplant (Solanum melongena L.) to drip or subirrigation in the spring-summer typical growing conditions of the Mediterranean area, where salty water is often used. Four F1-hybrids (Talina, Nilo, Birgah and Black Bell) were grown into pots in trough benches in a recirculating water system. The EC value of the nutrient solution, prepared using NaCl-enriched water (10 mM), was 3.2-3.5 dS m 1 until the first fruit harvest and reduced to 2.3-2.5 dS m 1afterwards; the salinisation induced a nutrient solution turnover whenever the EC value exceeded 7.0 dS m-1. Nutrient solution supply with drip irrigation was 32% more than with subirrigation, due to runoff and the need of a more frequent complete renewal. As a consequence, subirrigation allowed a higher fertigation efficiency (91 vs 79%) and an easier and cheaper management of the nutrient solution; nevertheless, the water use efficiency referred to the fruit yield was similar with both the irrigation methods, since the higher water supply with drip irrigation was counterbalanced by the significant higher yield (roughly +50%) compared with subirrigation, which caused a very high accumulation of salts in the upper layer of the substrate. These results suggest that subirrigation of eggplant may be problematic with high water EC, due to high water requirements of this species