Abstract: With open-top chamber, this paper studied the photosynthetic characteristics of Ginkgo biloba, a main greening tree species in Shenyang, under elevated ozone concentration. The results showed that after 50 days exposure to 80±8nmol·mol^-1 elevated ozone, the net photosynthestic rate of G. biloba leaf decreased significantly, with a decrement of 33.90%. The leaf carotenoid content increased notably, while chlorophyll content changed a little, with the ratio of chlorophyll a to chlorophyll b declined first and ascended then. No significant change was observed in leaf soluble sugar, while soluble protein and starch contents decreased obviously with time. The leaf malondialehyde (MDA) content was increased with time, and the increment was 79.53% on the 80th day of exposure. The decline of G. biloba photosynthesis had no correlation with the changes of chlorophyll content, but correlated markedly with membrane lipid peroxidation. The decline of the photosynthesis caused the decrease of leaf soluble protein and starch contents, resulting in a slow growth of the tree.

Key words: Phaiozem, Burozem, Methamisophos, Rhizosphere, Degradation-detoxification