WATER USE EFFICIENCY OF GREENHOUSE SUMMER SQUASH IN RELATION TO THE METHOD OF CULTURE: SOIL VS. SOILLESS

The experiment was conducted in a polyethylene greenhouse at the experimental farm of Tuscia University, central Italy. The aim of this study was to determine yield, water requirement and water use efficiency (WUE) of a zucchini squash (Cucurbita pepo L. cv ‘Afrodite’) in relation to the method of culture: soil versus closed soilless systems using three growing media (cocofiber, perlite and pumice). The increment rate was higher in soilless in comparison with soil. During the growing cycle, the water use in soil (256 L m^-2) was higher compared with the water requirements of plants grown respectively in cocofiber (221 L m^-2), perlite (200 L m^-2) and pumice (185 L m^-2). Marketable fresh fruit weight per unit of transpired water was more pronounced in closed soilless in comparison to the soil culture as indicated by the slope values of the regression equations: pumice (32.6 g L^-2), perilte (28.3 g L^-2), cocofiber (25.5 g L^-2) and soil (21.2 g L^-2). The yield water use efficiency calculated on fresh weight basis ranged from 4.3 to 28.5 g kg^-1 for pumice, 13.0 to 26.4 g kg^-1 for cocofiber, 3.9 to 23.4 g kg^-1 for perlite and 1.0 to 13.1 g kg^-1 for soil culture. The results demonstrated that the growers may improve, yield, water requirement and water use efficiency by switching from soil to closed soilless culture.