Root growth in corn and soybeans: effects of cadmium and lead on lateral root initiation

Abstract

This study examines the previously reported inhibitory effects of Cd on root growth. In hydroponic experiments, 100 μg Cd/ℓ effected a 33% inhibition of lateral root initiation of corn. The growth of corn and soybean primary roots was not reduced at Cd concentrations of 1 mg/ℓ, and the number of lateral root initials in soybeans was not reduced at 2 mg Cd/ℓ. The toxic effects of Cd were ameliorated by additions of Zn or by additions of Fe citrate to nutrient growth solutions. While both Zn and Fe additions did result in increased lateral root initiation, the number of initials was significantly lower than the controls. Lead had no effect on the initiation of soybean lateral roots at a concentration of 100 μg Pb/ℓ. However, 5 mg Pb/ℓ did effect a 21% decrease in corn lateral root initials, but this decrease could not be demonstrated with higher Pb concentrations.