The effect of salinity and nitrogen on nutrient distribution, citric acid and vitamin C in hydroponics

The effect of salinity and nitrogen on yield, vitamin C, citric acid and nutrient distribution of tomato in hydroponics culture was investigated. Tomato seeds were first let germinate in yonolit pots with wet coco peat and then their seedlings were transferred to plastic tanks containing 5 liters nutrient solution. Treatments were three levels of salinity (0, 30 and 60 mM as NaCl and CaCl2) and three levels of nitrogen (0, 1.5 and 3% as NH4Cl and NH4H2PO4 and 2:1 w/w). The results showed that nitrogen application increased wet and dry weights but salinity decreased them. Furthermore, salinity application had no effect on vitamin C, but 60 mM salinity increased citric acid compared to that of control. Nutrients distribution varied in different parts of then plants. Salinity increased iron and manganese uptake, but it had no effect on uptake of other nutrients. Salinity and nitrogen application reduced this inappropriate effect.