Response of cherry tomato to electrical conductivity of the nutrient solution

Closed loop soilless systems improve water and fertilizer use efficiency compared to open loop systems, but the mineral elements not taken up increase the electrical conductivity (EC) of nutrient solution. Moderate brackish water is particularly recommended for production of high quality tomatoes, especially cherry type. The research aim was to study production and quality of tomato (cv. Naomi) grown in NFT (Nutrient Film Technique, with discontinuous cycle) at two levels of nutrient solution EC (2-5 and 4-10 dS(.)m(-1)). At each harvest fresh weight and number were measured of discarded and marketable fruits, divided into size classes (diameter < 25 mm, 25-35 mm, and > 35 mm). On the marketable fruits, polar and equatorial diameter, dry matter content, total soluble solids, titratable acidity, vitamin C, and the main inorganic ions were determined. Production from low EC plants was higher than the high EC one (2.9 vs. 2.2 kg/plant) due to higher weight and size of fruits. The high EC treatment increased fruit dry matter content (9.0 vs. 7.8%), total soluble solids (7.4 vs. 6.7 degreesBrix), titratable acidity (0.70 vs. 0.64 g/100 ml of juice of citric acid), Na+, K+, and Cl- contents. The low EC plants consumed more water than high EC plants (100 vs. 87 L), but they had the same water use efficiency, referred to fresh fruit yield.