MINERAL NUTRIENT CONTENT OF TOMATO PLANTS IN AQUAPONIC AND HYDROPONIC SYSTEMS: EFFECT OF FOLIAR APPLICATION OF SOME MACRO- AND MICRO-NUTRIENTS

Effects of foliar applications of some micro- and macro-nutrients on mineral nutrient content of tomato leaves and fruits were investigated in an aquaponic system in comparison with a hydroponic system. Fourteen days old tomatoes seedlings were transplanted on to growth bed of aquaponic and hydroponic systems. Foliar nutrients application began 30 days after transplantation. Eight treatments were used, untreated control and foliar application at the rate of 250 mL plant^?1 with 0.5 g L^?1 potassium sulfate (K₂SO₄), magnesium sulfate (MgSO₄ 7H₂O), ferrous (Fe)- ethylenediamine-N,N′-bis (EDDHA), manganese sulfate (MnSO₄ H₂O), boric acid (H₃BO₃), zinc chloride (ZnCl₂), and copper sulfate (CuSO₄ 5H₂O). Foliar application of potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) increased their corresponding concentrations in the leaves of aquaponic-treated plants. On the other hand, foliar spray of K, Fe, Mn, Zn, and Cu caused a significant increment of applied element concentrations in the fruits of hydroponic-grown plants. These findings indicated that foliar application of some elements can effectively alleviate nutrient deficiencies in the leaves of tomatoes grown on aquaponics.