Comprehensive comparison of different saline water irrigation strategies for tomato production: Soil properties, plant growth, fruit yield and fruit quality

Saline water has been increasingly used for crop production in areas characterized by freshwater shortage. However, continuous irrigation with saline water often results in adverse effects on the soil-crop system. In this study, we investigated the effects of different saline water irrigation strategies on soil properties, tomato plant growth, fruit yield and fruit quality. The irrigation treatments included (i) continuous irrigation with freshwater (Fe, (ii) continuous irrigation with saline water (SI), (iii) irrigation with the saline water blended with freshwater (BI), (iv) irrigation alternately with saline water and freshwater (Al), and (v) irrigation with freshwater at early sensitive stages combined with saline water at later tolerant stages (CI). Overall, saline water irrigation adversely affected the soil-crop system by increasing pH, electrical conductivity, salt ions (Na+, Cl- and SO42-) and sodium adsorption ratio in soils and Na+ in plant tissues, and by decreasing K+/Na+ in both soils and plant tissues, the relative growth rates of plant height and leaf area, plant biomass and fruit yield (compare SI versus FI). However, these adverse effects of saline water on the soil-crop system were generally alleviated by the BI, AI and CI treatments compared to the SI treatment. Despite this, there was no distinct difference in soil properties among the BI, AI and CI treatments. The AI treatment generally showed higher fruit yield as compared to the BI and CI treatments, and even no significant difference as compared to the FI treatment in two out of three cropping seasons. In addition, the AI treatment significantly increased vitamin C, soluble sugar and solids, glucose, fructose and sucrose in tomato fruits as compared to the FI treatment. Our results suggested that the alternate irrigation (AI) was more efficient than the blending (BI) and cycling (CO irrigation in alleviating the adverse effects of saline water on the soil-crop system.