The Influence of salinity and nitrogen on tomato fruit quality and micronutrients concentration in hydroponic culture

Salinity plays an important role in the reduction of tomato growth, especially in arid and semi-arid regions. Nitrogen (N) may increase tomato tolerance to salt stress by increasing plant growth. In order to investigate the interaction effect of salinity and nitrogen on tomato growth, fruit quality, and micronutrient concentration in tomato plants, a hydroponic experiment was conducted in a completely randomized design with three replications. Treatments included 3 salinity levels (0, 30 and 60 mM), and 3 nitrogen rates (0, 1.5, and 3 mM). Results indicated that salinity decreased tomato height, shoot and fruit fresh weight, and increased citric acid in tomato fruit and consequently caused blossom-end rot in tomato fruit. However, salinity improved fruit quality (flavor). The use of N increased plant height, shoot, and fruit fresh weight compared to control. By application of N to saline nutrient solution, plant height increased. Salinity increased concentration of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in roots, as`well as Fe and Cu in fruit. Increasing N rates in nutrient solution increased micronutrients concentration in tomato roots. Interaction of 60 mM salinity and N decreased micronutrients concentration in root, compared to control. Our tentative conclusion shows that the addition of N to the nutrient solution may decrease detrimental effect of salinity on the growth of tomato plants.