Pääkkönen E, Holopainen T, Kärenlampi L
Department of Ecology and Environmental Science, University of Kuopio, PO Box 1627, 70211, Kuopio, Finland.
Environ Pollut. 1997;95(1):37-44. doi: 10.1016/s0269-7491(96)00113-3.
Forty clones of Betula pendula and 6 clones of Betula pubescens, originating from southern and central Finland, were ranked in order of ozone sensitivity according to visible injuries, growth and leaf senescense under low ozone exposure. The plants were fumigated in natural climatic conditions using an open-air exposure system during two growing seasons. Control plants were grown under ambient air, and the elevated-ozone exposures were 1.6x the ambient in 1994 and 1.7x the ambient in 1995. The differences in ozone sensitivity among clones were large. Ozone tolerance was related to thicker leaves and higher stomatal density as compared to sensitive clones. Ultrastructural ozone-induced symptoms were found in chloroplasts of sensitive clones. Increased number of visibly injured leaves on fumigated plants was correlated with reduced leaf formation, foliage area, shoot dry wt and number of stomata, and increased yellowing of leaves. The results suggest that a considerable proportion of birch trees, showing high sensitivity to ozone, are at risk if ambient ozone exposures increase.
根据低臭氧暴露条件下的可见损伤、生长情况和叶片衰老情况，对来自芬兰南部和中部的40个垂枝桦克隆和6个毛桦克隆按照对臭氧的敏感程度进行了排序。在两个生长季节中，利用露天暴露系统在自然气候条件下对这些植株进行熏蒸处理。对照植株在环境空气中生长，1994年臭氧浓度升高组的臭氧暴露量为环境浓度的1.6倍，1995年为1.7倍。不同克隆对臭氧的敏感程度差异很大。与敏感克隆相比，耐臭氧性与叶片较厚和气孔密度较高有关。在敏感克隆的叶绿体中发现了超微结构的臭氧诱导症状。熏蒸处理植株上可见损伤叶片数量的增加与叶片形成减少、叶面积、茎干重和气孔数量减少以及叶片黄化增加相关。结果表明，如果环境臭氧暴露增加，相当一部分对臭氧高度敏感的桦树将面临风险。
