Tomato Root: Site of Initial Alteration in Minor Elements in Cadmium Treated Plants

Abstract

Tomato plants treated with 0.25 and 0.75 ppm Cd for one month exhibited no visual symptoms of toxicity, nor was the percent dry weight of leaf, stem, or root tissue altered. Cadmium concentrations in treated plants generally followed the trend: roots > leaves > stems. At such concentrations too low to cause phytotoxicity, cadmium altered the minor element concentration in tomato plants. The first changes occurred in the Mn and Fe concentrations of the roots. The reduction of these elements in the root may signal an early event in the mechanisms of Cd toxicity. To test the hypothesis that the root represents the primary site of injury from Cd, a kinetic study should be conducted in which root and shoot tissues are analyzed for Cd and the minor elements as the plants progress from an asymptomatic condition to one of severe Cd toxicity. (JMT)