Effect of Both Soil Copper Applications and Foliar Copper Application Frequencies on Macronutrients Contents of Tomato Plants

Abstract

Copper-containing fertilizers, fungicides and bactericides are extensively used to control plant diseases in greenhouses in Turkey. These materials are applied from both soil and foliar. Excessive applications of these materials have led to the imbalance the mineral nutrition of plants. The objective of this study was to evaluate the effects of both soil copper applications (SCuA) and foliar copper application frequencies (FCuAF) on macronutrient contents (nitrogen [N], phosphorus [P], potassium [K], calcium [Ca] and magnesium [Mg]) in different organs of tomato plants grown in greenhouse. For this purpose, tomato seedlings were grown for 8 months in a computer-controlled greenhouse and Cu was applied as a factorial combination of rate (0 [S1], 1000 [S2] and 2000 [S3] mg kg^-1, soil) and frequencies (no application [F1], biweekly [F2] and weekly [F3], foliar). Two separate experiments were conducted to observe effects of different Cu-containing chemicals. Two fungicides, Gunner and Tenn-Cop 5E (containing Cu oxychloride and copper salts of fatty and rosin acids, respectively) were used for foliar copper applications, CuSO₄·5H₂O was used to provide copper to soil. In the experiment-I (Gunner, Cu oxychloride), both SCuA and FCuAF did not affect total N contents of plant samples. P content of leaf was improved with SCuA and FCuAF. However, FCuAF generally caused a decline P contents in fruit and root. SCuA initially resulted in an increase and then a decrease in K content of leaf while decline in root samples. FCuAF caused a decline in K content in fruit. Ca content in root was positively affected by SCuA, however FCuAF initially resulted in an increase then a decrease in Ca content of root. Ca contents of fruit and leaf were not changed by any treatment. Mg content of root samples increased with SCuA and decreased with FCuAF. Mg contents of fruit and leaf were not affected by any of the treatments. In the experiment-II (Tenn-Cop 5E, copper salts of fatty and rosin acids); total N content of leaf samples increased due to SCuA and FCuAF, SCuA and FCuAF resulted in a decline in N content of fruit. N content of root did not show any change. P content of leaf increased with SCuA

and generally decreased with FCuAF. P contents of fruit and root samples were decreased by FCuAF. K contents of leaf samples were found to be increased by SCuA while K content in root dropped. K content of fruit initially increased and then decreased with SCuA and decreased with FCuAF. In addition, FCuAF were not found to be effective on leaf and root K contents. In general, Ca content of leaf was found to be increased by SCuA and generally decreased by FCuAF. None of the applications was found to be effective on Ca content of fruit. Ca content of root was positively affected by SCuA. Mg content of leaf samples were not affected by any of the applications. Mg contents of root and fruit were increased by SCuA and decreased by FCuAF. As a result, both SCuA and FCuAF, especially aiming to control plant diseases, showed different effects on N, P, K, Ca and Mg contents and imbalance the mineral nutrition of tomato plants. Combined applications of Cu to soil and leaves could be more deleterious to plants when Cu is applied only to soil or leaves.