Effects of acute ozone stress on reproductive traits of tomato, fruit yield and fruit composition.

BACKGROUND Tomato is sensitive to ozone. Fruit growth and composition are altered under ozone stress by modification of reproductive development. Fifty-one-day-old plants were exposed to three concentrations of ozone (200, 350 and 500 µg m(-3)) for 4 h. RESULTS Ozone reduced well-developed fruit number and fruit size, but it did not significantly affect flowering rate and fruit setting rate. The effect of ozone depends on organ developmental stage at the time of ozone application, as flowers and young fruits at the time of ozone exposure were more affected. Contents of total soluble sugars (total SS), total organic acids (total OA) and ascorbic acid (AsA) increased in fruits harvested from ozone-treated plants. Tomato fruit composition was altered under ozone stress, leading to a lower sugar:acid ratio. These changes were mostly due to increased contents of malic acid, ascorbate and glucose despite a decrease in sucrose. CONCLUSION Acute ozone exposure up to 500 µg m(-3) greatly influences tomato fruit quality. As final fruit yield was not significantly reduced, it highlighted that there may be compensatory mechanisms present in the reproductive structures of tomato. Further research would be necessary to determine how reproductive traits are affected by repeated ozone exposure or longer-term exposure.