Sammendrag
Previous experiments have shown that several European clovers may develop more visible injuries due to ozone when the night is not dark. At high latitudes, the summer nights are bright, giving the background for the question whether plants adapted to midnight sun also have this response of being more easily injured by ozone when the night is not dark.
The plants included in the present experiment are expected to be adapted to light exposure during night, since there is midnight sun from the time they melt out of the snow cover in spring until the end of July, in the sites where they were collected. This constitutes about 50 % of the growing season for grassland species in these areas.
Cuttings of two genotypes of white clover (Trifolium repens) collected in two sites in subarctic Norway were cultivated under controlled environment conditions. Using a factorial design, the plants were exposed to two different night-time light conditions and two different ozone exposure levels. We studied the development of visible injuries, foliar chlorophyll concentrations and N concentration as signs of premature senescence due to ozone.
Vis fullstendig beskrivelse