Ozone risk assessment of grapevine 'Cabernet Sauvignon' using open-top chambers

Objective: Ground-level ozone (O-3) is an important photochemical pollutant that can damage plant tissue structures, seriously affect plant physiological metabolism and biochemical reactions, inhibit plant growth and accelerate leaf senescence. Some ozone-sensitive grape varieties show ozone injury symptoms in the field. The purpose of this study was to study the effects of long-term O-3 stress on the plant growth, fruit quality, carbon and nitrogen absorption and distribution of the main cultivar 'Cabernet Sauvignon'. Methods: O-3 was administered for 2 h daily for three months to three-year-old Vitis vinifera L.cv. 'Cabernet Sauvignon' grapes at 75 nL/L, and the effects of O-3 stress on the grape plants, the fruit growth and development, the leaves of photosystem II (PSII) and Psi activity and the carbon and nitrogen absorption and distribution were analyzed. Results: The results suggest that ozone pollution substantially affected the growth and physiology of 'Cabernet Sauvignon'. Plant biomass and fruit quality were also negatively influenced by ozone pollution. Chlorophyll fluorescence analysis showed that O-3 stress caused noticeable decreases in the maximum fluorescence F-m and the maximum photooxidizable P700 (Pm); the actual photochemical efficiency of PSII Y(II) decreased significantly, but the quantum yield of regulated energy dissipation Y(NPQ) increased significantly; the Psi donor side limitation Y(ND) increased, but there was no significant change in the Psi acceptor side limitation Y(NA); and the actual photochemical efficiency of Psi decreased. The carbon and nitrogen labeling of plants revealed that after O-3 stress, compared with the control, the amounts of N-15 and C-13 absorbed by the leaves were significantly reduced, the amounts of N-15 and C-13 absorbed by the roots were significantly increased, and the proportions of N-15 and C-13 transported to the fruits were significantly reduced.