Effects of Lead Toxicity on Soybean (Glycine Max): Ion Transport and Anatomical Structure

Lead nitrate caused an inhibition in sodium accumulation in the root of soybean plants. Sodium accumulation in the stem and leaf was increased at 21-day plants subjected to lower concentration of lead nitrate treatment. The accumulation of potassium in the root and stem was decreased following lead nitrate treatment but potassium content in the leaf was increased. Lead nitrate increased nitrate accumulation in the stem and decreased that in the root and leaf of soybean plants. The accumulation of phosphate in the root and stem of soybean plants was decreased but that in the leaf was increased. Lead nitrate dramatically decreased the dry weight of root, stem and leaf. Lead treatment resulted in the anatomical changes in stems and roots of soybean e.g. smaller vascular cylinder, more cortical layer with larger cell size, irregular size of cambium ring, disorganized and deformed shape of metaxylem and protoxylem etc. Lead nitrate also caused chlorosis and brown spots in leaf at different level of treatments. The relationship between anatomical structures and ion transport will be discussed.