Effects of chromium and lead mixture on pea?s growth, ultrastructure, translocation and their accumulation in organs

Soil heavy metals have led to an increased risk to environment and food. In current decades, a large number of studies have focused on plant strategies for controlling water level, avoiding oxidative stress and maintaining essential functions to better elucidate the physiological and morphological changes in plants go through for their survival in a variety of environments. As a result, many terrestrial ecosystems (natural and agricultural) would be significantly impacted through effects of chromium and lead with some potentially collapsing owing to plant extinction. K2Cr2O7 and Pb(NO3)2 were added to soil to grow pea seedlings to examine the adsorption, translocation and accumulation of Cr and Pb in root, stem and leaf of pea and effects on the pea growth and distribution. Results showed that depending on the concentrations of Cr and Pb, the stem height of the pea was decreased by 3.5-25.4%, while the root length of the pea was reduced by 22.3-47.6%. Cr and Pb mixed pollution induced the granular callose that accumulated and attached to vessel wall in xylem. The morphology of pea's root, stem and leaf surface and cross section and EDS via scan electronic microscopy were altered. The results uncovered new toxic mechanism and newly understanding of toxicity of Cr and Pb to pea.