Lead tolerance during germination and early growth of the Brazilian peppertree and the morpho-physiological modifications

Abstract

Woody plants are important for phytoremediation systems, and few species of lead hyperaccumulators are known. We evaluated the lead (Pb) tolerance of Schinus molle L. plants and the resulting anatomical and physiological modifications during germination and early growth. Two experiments were conducted to evaluate the response of S. molle seeds and plants to exposure to five concentrations of Pb(NO3)2 (0.0, 0.5, 1.0, 2.0, and 5.0 mM). The seed germination and seedling growth were unaffected, and the accumulation of Pb was higher in the roots than in the shoots. The root and leaf anatomy was significantly modified, but the internal structure exhibited no evidence of toxicity. S. molle accumulated Pb to levels close to those of metal-tolerant plants, although the Pb translocation decreased proportionately as the Pb concentration of the solution increased. Thus, S. molle accumulated Pb to concentrations above toxic levels and showed only favorable modifications to the anatomical structure and growth, suggesting this species is Pb tolerant and has the potential for use in phytoremediation systems.