7. Yamaguchi, M., Watanabe, M., Iwasaki, M., Tabe, C., Matsumura, H., Kohno, Y. and Izuta, T. (2007) Growth and photosynthetic responses of Fagus crenata seedlings to O3 under different nitrogen loads. Trees, Vol. 21 No. 6, 707-718.
Abstract
To obtain basic data for evaluating the critical level of ozone (O3) for protecting Japanese deciduous broad-leaved forest tree species, growth and photosynthetic responses of Fagus crenata seedlings to O3 under different nitrogen (N) loads were investigated. The seedlings were grown in potted andisol supplied with N as NH4NO3 solution at 0, 20 or 50 kg ha-1 year-1 and were exposed to charcoal-filtered air or O3 at 1.0, 1.5 and 2.0 times the ambient concentration for two growing seasons. There was a significant interactive effect of O3 and N load on the whole-plant dry mass of the seedlings at the end of the second growing season. The O3-induced reduction in the whole-plant dry mass of the seedlings was greater in the relatively high N treatment than that in the low N treatment. This interactive effect was mainly due to the difference in the degree of O3-induced reduction in net photosynthesis among the N treatments. The degree of O3-induced reduction in the N availability to photosynthesis was greater in the relatively high N treatment than that in the low N treatment. In conclusion, the sensitivity of growth and photosynthetic parameters of F. crenata seedlings to O3 become high with increasing the amount of N added to the soil. Therefore, N deposition from the atmosphere should be taken into account to evaluate the critical level of O3 for protecting Japanese deciduous broad-leaved forest tree species.
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最終更新：2008年03月08日 04:01
