CUMULATIVE TROPOSPHERIC OZONE EFFECT ON VISIBLE TOBACCO LEAF INJURY

摘要

Tropospheric ozone is one of the most phytotoxic air pollutants. It can cause visible injuries, plant growth reduction and yield losses, resulting in economic losses. The effect of ozone on plants is cumulative during the growing season. Hence, in this study we examined the cumulative tropospheric ozone effect on ozone-sensitive tobacco plants (cultivar Bel W3) during one-month exposure in the summer season. The comparison of ozone-caused visible leaf injury in forest and urban sites in relation to cumulative ozone concentration is also presented here, as well as determination of the best index of visible ozone injury. The differences in visible tobacco leaf injury between forest and urban sites were assessed using two proposed indices for assessing the cumulative ozone effect. Both proposed indices revealed tendencies in ozone-caused injuries in particular weeks of the experiment and exposure sites. Higher differences between sites and week of exposure were revealed by the first index, which was calculated on the basis of the three maximum values of ozone leaf injury. Moreover, the examined cumulative ozone effect appeared earlier in the forest site, where higher ozone concentrations were noted. However, a stronger plant response was estimated in the urban site during the last week of experiment, even though lower ozone concentrations were observed.