Abstract:

【Objective】 High levels of atmospheric ozone (O₃), which is an important secondary air pollutant with strong oxidizing capability, can reduce the quantity and quality of vegetation production by damaging the functions and physical structure of plant cells. Therefore, in order to establish a basic understanding of the effects of O₃ on crop production, the present study investigated the effects of different O₃ concentrations, including AOT40, on the growth (hypocotyl length), biomass (dry weight) and leaf health of cherry reddish (Raphanus sativus). 【Method】 Raphanus sativus were grown in growth chambers under four different O₃ concentrations (30, 50, 70 and 90 nmol/mol), and the growth, biomass and foliar injury status of the plants were assessed on a weekly basis for 4 weeks. 【Result】 ① The O₃ injury symptoms that were observed under 70 and 90 nmol/mol (i.e., cotyledons with chlorotic stippling and inconsistent thickness) developed within the first week of O₃ fumigation, and the injury symptoms intensified with the duration of treatment. Furthermore, the proportion of leaves with injury symptoms was positively correlated with AOT40 (accumulated O₃ exposure over a threshold of 40 (nmol/mol) (P<0.01). ② Meanwhile, elevated O₃ concentrations significantly reduced dry mass and hypocotyl size since the 3^rd week. At the end of 4^th week, the dry mass of hypocotyl had been reduced by 45.1%, 57.3% and 79.9% in 50, 70 and 90 nmol/mol O₃ treatments, respectively, when compared to the control group. In addition, the reduction of hypocotyl exhibited a linear relationship with AOT40, and dry mass declined more rapidly than hypocotyl size.【Conclusion】 The growth, biomass and injury symptoms ofRaphanus sativus were affected by both O₃ concentration and duration of exposure.

Key words: atmospheric ozone(O₃), AOT40, Raphanus sativus L., hypocotyl, biomass, injury symptom