Copper and zinc distribution and toxicity in ‘Jade’ / ‘Genovesa’ young peach tree

Abstract

The frequent application of fungicides containing copper (Cu) and zinc (Zn) in orchards can lead to accumulation of these metals in soil at toxic levels. The aim of this study was to evaluate Cu and Zn distribution and toxicity in young peach trees grown in Cu and Zn supplemented soil. For this purpose, a pot experiment was carried out in a greenhouse using a Typic Hapludalf soil under natural conditions. The two-factor experiment investigated the combination of Cu (0, 30 and 60 mg kg−1) and Zn (0, 15, 30, 60, 120, and 180 mg kg−1) rates in four replicates per treatment. ‛Jade’ young peach trees [Prunus persica (L.) Batsch] grafted on ‛Genovesa’ (P. salicina) propagated by herbaceous cuttings were then cultivated for 78 days with one plant per pot. Height increase, dry matter production, Cu and Zn concentration in plant organs, photosynthetic pigments and antioxidant activity were evaluated. Soil available Cu and Zn content increased with the rate. Consequently, plants presented Zn, and mainly Cu, accumulation mechanisms in root system, reduced transport of both elements to leaves, where toxic effects of heavy metals was observed. However, combining high content of soil available Cu and Zn, especially at higher doses, resulted in decreased production of dry matter production. Biochemical parameters were also affected. The SOD activity was smaller in peach leaves grown in the soil supplemented with Cu, while the chlorophyll a and b content decreased according to the increase of Zn rate, compromising the antioxidant response and the photosynthetic activity. Thus, increasing soil available Cu and Zn contents in sandy soil with low organic matter soils may maximize toxic effects to young peach trees.