Peroxidase activity and total phenol content in citrus cuttings treated with different copper sources

The proper citrus cutting choice is considered of basic importance for a healthy and productive citriculture. Substrates composed of organic materials are widely used for the production of citrus seedlings but this can lead to plant copper deficiency, mainly caused by substrate high chelating properties. Copper is an essential heavy metal and is involved in many different plant physiological processes. This experiment was carried out in order to evaluate the behavior of ‘Rangpur lime’ lemon rootstock (Citrus limonia Osbeck) grafted with cv. ‘Valencia’ (Citrus sinensis L. Osbeck), when treated with different copper formulations, as cupric oxychloride (50% Cu — Novartis Biociências™), cuprous oxide (32.8% Cu — Yara Vita™), chelated copper (5% Cu — Stoller™) and copper sulphate (25% Cu — Microsal™) analyzing the activity of peroxidase (POD) and the total content of phenols. The different copper formulations did not show significant differences about plant height, diameter, leaf and root dry weight. The comparison among copper treatments shows that cuprous oxide promoted the antioxidant system (POD activity and phenolic content) while chelated copper was not effective.