Effects of Ambient Ozone Concentrations on Contents of Nonstructural Carbohydrates in Phoebe bournei and Pinus massoniana Seedlings in Subtropical China

Abstract

Ground-level ozone (O3) pollution has affected carbon metabolism in tree species, which becomes one of the top environmental issues in China. In this paper, 1-year-old seedlings of Phoebe bournei and Pinus massoniana Lamb. were grown under field conditions at a rural site near the city of Taihe (Jiangxi Province). The plants were exposed in open-top chambers either to charcoal-filtered air or nonfiltered ambient air for 145 days. At the end of the growth season, the plants were harvested and the major nonstructural carbohydrates in leaves and roots were determined. Exposure to nonfiltered ambient air compared with filtered air controls caused an increase of sucrose, glucose, fructose, starch, and total nonstructural carbohydrates (TNCs) in fine roots of Ph. bournei, while there is no change in carbohydrate contents in Pi. massoniana roots. Compared with filtered air, in Ph. Bournei, starch and TNCs in leaves were reduced by 48 and 7 %, respectively, in ambient O3. While, ambient O3 just increased TNC content by 8.9 % in Pi. massoniana needles compared to filtered air. In summary, ambient O3 affected carbohydrate metabolism of these two subtropical tree species in China, and Pi. massoniana was less sensitive than Ph. bournei. O3 induced much greater changes in the amounts of carbohydrates in roots than in leaves.