سارا دهنورد
محمد کاظم سوری
صدیقه مردانلو

Nitrogen is one of the most important and essential lelments for plant growth and development and it has an important role on quantitative and qualitative yield production in agriculture. This study was carried out to evaluate the effects of foliar application of nitrogen on qualitative traits of tomato fruits using a completely randomized design with five treatments and four replications under hydroponic culture system. Nitrigen was applied as foliar sprays in different concentrations of ammonium sulfate ۰, ۵۰, ۱۰۰ and ۲۰۰ mM once per week, as well as ۵۰ mM every other day. Based on the results, qualitive traits were affected by the treatments (P≤ ۰.۰۵). Foliar application of ammonium led to reduction in number of fruits, yield and vitamin C, but increased fruit juice pH, blossom end rot, and tiratable acidity. The results also showed that ammonium treatments increased diameter and length of fruits compared to the control plants, while hardness of fruit was not affected by treatments.