Does elevated ozone have differing effects in flowering and deblossomed strawberry?

Abstract

Fruiting and deblossomed plants of strawberry (Fragaria × ananassa) were exposed to 92 ppb ozone or filtered air in open-top chambers for 69 d. Flower and fruit production, relative growth rate of leaf area, leaf gas exchange and plant biomass were investigated. Ozone caused an initial acceleration in inflorescence production, which was followed by a reduction in inflorescence production, fruit set, and, later, individual fruit weight, although total fruit yield was not affected before the end of the fumigation period. Ozone accelerated leaf senescence and had a greater negative effect on the rate of photosynthesis in older than in younger leaves in fruiting and deblossomed plants, but the response of net photosynthesis to ozone did not differ between the two groups of plants. Relative growth rate of leaf area was the first parameter to be reduced by ozone fumigation, with the effect being significant in fruiting, but not in deblossomed, plants. Final above-ground biomass was also significantly decreased by ozone in fruiting plants, but not in deblossomed plants. Root and crown biomass were not significantly affected by ozone fumigation in either fruiting or deblossomed plants.