Effects of cadmium and zinc on ozone-induced phytotoxicity in cress and lettuce

Abstract

Cadmium or zinc solutions were applied to the foliage or roots of lettuce (Lactuca saliva L. cv. Grand Rapids) and cress (Lepidium sativum L. cv. Fine Curled) at concentrations of 100 parts per million (ppm) every 4th day for several weeks. Four weeks after sowing, plants were fumigated once with 30-35 parts per hundred million (pphm) ozone, for 6 h. Cress plants that had received soil application of cadmium showed markedly increased ozone-induced phytotoxicity in terms of visible leaf damage and pigment degradation; in lettuce, only pigment degradation was evident based on chlorophyll analysis. Soil application of zinc showed less ozone-induced phytotoxicity on cress and no pigment degradation in lettuce. Compared with soil application, foliar application of zinc or cadmium produced less effects on ozone phytotoxicity.