Ecotypic Response of Silene cucubalus to Air Pollutants (SO(2), O(3)).

Two populations of Silene cucubalus, from a rural and from a heavily polluted industrial area in Central Europe, were fumigated for 6 weeks with 160 μg SO(2)m (-3), for 4 weeks with 70 μg O(3) m (-3), and for 4 weeks with both air pollutants. Both populations were heavily affected in growth and completely hampered in flowering by O(3), alone or in combination with SO(2). The injurious concentration of O(3) stimulated the activity of peroxidase and reductive glutamate dehydrogenase and significantly diminished the concentration of magnesium and manganese in the leaves. SO(2) alone gave no growth reduction of the rural population and stimulated the growth of the industrial one. It diminished, however, the weight of the seed of the rural population by more than 20 %. The increased weight of the seed of the industrial population after SO(2) exposure and its better growth in the presence of SO(2) are discussed in relation of the evolution of SO(2) tolerance. Both populations have a different sensitivity against ozone with the highest sensitivity in the industrial population. This is the first report of a plant species which is able to evolve SO(2) tolerance and heavy metal tolerance.