DIFFERENT SENSITIVITIES OF THE STRAWBERRY CULTIVARS ELSANTA, KORONA, POLKA, AND TENIRA TO OZONE

The effects on leaf gas exchange, chlorophyll fluorescence, and ethene production following ozone exposure to 160 ppb for 12 h during 4 days were compared between the strawberry cultivars 'Elsanta', 'Korona', ' Polka', and 'Tenira' to work out differences in their ozone tolerance. 'Tenira' was the most tolerant cultivar, followed by 'Elsanta', 'Polk a', and 'Korona'. The sensitivity corresponded to the stomatal conduct ance, which was smallest in 'Tenira' and largest in 'Korona' during oz one fumigation. Two characteristics protecting against ozone were dist inguished, the first present in 'Tenira', the second in 'Elsanta'. In 'Tenira', the guard and subsidiary cells reacted sensitive to ozone st ress and narrowed stomatal aperture, so that less ozone entered the pl ant. The stomata of 'Elsanta' plants were only slightly affected by oz one, but characterized by a distinctly narrower aperture in comparison to 'Korona', 'Polka', and 'Tenira' at unstressed conditions. It is co ncluded that 'Elsanta', which is frequently cultivated in Germany, is characterized by a comparatively high capacity to tolerate ozone.