EFFECTS OF SULFUR-DIOXIDE ON GROWTH, PHOTOSYNTHESIS AND ENZYME-ACTIVITIES OF CHINESE GUGER-TREE SEEDLINGS

The Chinese Guger-Tree (Schima superba Gard et Champ var. superba) is an important hardwood species in Taiwan where the ambient SO2 concentration in some areas is high. Seedlings were raised in field chambers with and without SO2 to determine whether this species is affected by this pollutant. After 4 weeks of exposure to 325 ppb of SO2 the photosynthetic rate of seedlings decreased immediately. During the fumigation period, stent height growth was not inhibited, however, the stem diameter growth was reduced significantly. The dry weight of leaves was unchanged while stem, root and total seedling weight were lower than those of control plants. Sulfhydryl groups in leaves increased by 75%, whereas they did not change in roots following SO2 uptake, Superoxide dismutase in leaves did not change, however, peroxidase activity increased significantly. Results suggest that ambient SO2 in some areas in Taiwan may affect the physiology, and growth of the Chinese Guger-Tree.