Efficiency of chelate forms of micronutrients in nutrition of greenhouse tomato grown in rockwool

Cultivation of vegetable crops on rockwool medium under controlled conditions requires the use of completely soluble forms of fertilizers for preparing nutrient solution. In order to prevent immobilization of metal microelements, especially Fe, they are often used in chelated forms. The low biodegradability of currently popular chelating agents may lead to contamination of the environment by these compounds. The aim of the present study was to evaluate whether it is necessary to use chelated forms of Cu and Mn. Another objective was to assess the applicability of two chelating agents of iron in cultivation of tomato on rockwool slabs. Mineral forms of manganese (MnSO4 H2O) and copper (CuSO4 5H2O) were compared with EDTA+DTPA chelate forms of these nutrients. In the case of Fe, the suitability of EDTA and DTPA as the chelating agents was evaluated, taking into account the crop yield as well as nutritional status of tomatoes in different stages of growth. The results of our greenhouse trials proved that application of chelate forms of Cu and Mn did not alter the total yield of tomato fruits but accelerated fruit maturation, so that early tomato yield was higher than in response to mineral forms of these nutrients. Plants supplied with Cu and Mn chelates contained higher amounts of these nutrients in index parts of tomatoes analysed from May to August in one-month intervals. The use of DTPA and EDTA as chelating agents was just as productive in terms of tomato fruit yield. However, the DTPA chelate contributed to better plant nutrition with Fe, as well as Cu and Mn.