Effect of the Desalinated Water Blend and Type of Growing Media on the Quality of Tomato Fruit in a Mediterranean Greenhouse

Desalinated seawater (DSW) is nowadays a competitive alternative for irrigating intensive greenhouse crops in regions with scarce water resources. This research, carried out for three years, analyzed the effects of three desalinated seawater (DSW) blends with different salinity levels and two common growing media (soil and soilless) on the fruit quality of a tomato crop grown under Mediterranean greenhouse conditions. To analyze the effect of the three experimental factors on fruit quality, a randomized block design layout was employed, and a multifactorial ANOVA analysis was conducted. Four successive harvests were performed in each growing cycle at similar dates and under consistent crop conditions to analyze the effect of harvest timing on fruit quality. Fruit quality parameters, such as fresh and dry weight, fruit diameter, total dissolved solids (TDS), and firmness, were measured on a representative sample of fruits from each harvest, treatment, and growing cycle. Results showed that the experimental factors studied significantly influenced fruit quality. Increasing salinity treatments reduced fruit size but improved fruit quality. The growing media had no significant effect on fruit size, although soilless crops yielded better quality fruits than the soil-grown ones. Later harvests tended to provide lower-yield but higher-quality fruits. This study demonstrates that the conjunctive use of DSW and conventional water can help to improve both quality and yield of tomato fruit while guaranteeing the sustainability of the greenhouse horticultural system.