Saeed Alah Tavakoli - Ph.D Student of Horticultural Science, Jahrom Branch, Islamic Azad University, Jahrom , Iran
Abdolhossein Abootalebi Jahromi - Associate Professor of Horticulture, Jahrom Branch, Islamic Azad University, Jahrom, Iran
Abdolrasoul Zakerin - Assistant Professor of Horticultural Science, Jahrom Branch, Islamic Azad University, Jahrom, Iran
Abdolkarim Ejraei - Department of Horticulture, Jahrom Azad University, Jahrom, iran
hamed Hassanzadeh Khankahdani - Horticultural Expert, Management of Horticulture, Agricultural Organization Fars, Shiraz, Fars, Iran.

Plant growth in hydroponic systems is affected by the nutrient solution concentration. The present study was conducted to assess the effect of nitrogen (N) and potassium (K) contents on the concentration of some nutrients, chemical fruit qualities, and yield in tomatoes (Solanum lycopersicum, cv. Hirad). The experiment was arranged as a completely randomized design with four treatments (T۱: N۱۶۰ + K۳۵۰ ppm at the vegetative stage and N۱۳۰ + K۲۵۰ ppm at the reproductive stage, T۲: N۱۷۰ + K۳۶۰ ppm at the vegetative stage and N۱۴۰ + K۲۶۰ ppm at the reproductive stage, T۳: N۱۸۰ + K۳۷۰ ppm at the vegetative stage and N۱۵۰ + K۲۷۰ ppm at the reproductive stage and T۴: N۱۹۰ + K۳۸۰ ppm at the vegetative stage and N۱۶۰ + K۲۸۰ ppm at the reproductive stage). Results indicated that the increase of N and K supply in nutrient solution decreased the Ca, Na, Mn, and Zn concentrations in the leaves. In contrast, the element content in the fruits was unaffected by the increase of N and K (except for Cu) and the second treatment (T۲) had the most beneficial effect on the Cu concentration in the leaves and fruits of tomato. Enhancement of the total soluble solid, chlorophyll, lycopene, and total acid could improve fruit quality in tomato fruits. The best treatment in the present study was N۱۷۰ + K۳۶۰ ppm at the vegetative stage and N۱۴۰ + K۲۶۰ ppm at the reproductive stage.

Macro and microelements, vegetative growth, Generative growth, vitamin c, TSS