Irrigation with saline water improves carotenoids content and antioxidant activity of tomato

The combined effect of increasing concentrations of NaCl in the irrigation water and fertilization with different nitrogen sources on the chemical com position of tomato (Lycopersicon esculentum Mill.) fruit was investigated. Increasing water salinity from 0.5 dS m(-1) (non-salinized control) to 15.7 dS m(-1) resulted in both reduced fruit size and fruit water content, wher eas it caused an increase in soluble solids, carbohydrates, sodium and chlo ride concentrations. Titratable acidity increased upon irrigation with sali ne water, whereas the fruit redness significantly decreased. In addition, s alinity reduced P, K+, Mg2+ and NO3- fruit concentrations. Total carotenoid s and lycopene concentrations expressed on both fresh- and dry-weight basis gradually increased from the non-salinized control to the 4.4 dS m(-1) tre atment (approximately 0.25% NaCl w/v) and they decreased at electrical cond uctivities of the irrigation water higher than 4.4 dS m(-1). Overall these data show that it is possible to improve carotenoid content and antioxidati ve activity of tomato, with an acceptable yield reduction, by irrigating wi th saline water containing NaCl up to 0.25% (w/v).