Effects of ozone exposure on growth and photosynthesis of the seedlings of Liriodendron chinense (Hemsl.) Sarg, a native tree species of subtropical China

Abstract

Little is known about the response of trees to elevated ozone (O 3 ) in the subtropical region of China, where ambient O 3 concentrations are high enough to damage plants. In this study, pigment content, gas exchange and chlorophyll (Chl) a fluorescence in leaves of Liriodendron chinense (Hemsl.) Sarg seedlings, a deciduous broadleaf tree species native in subtropical regions, were investigated at 15, 40, and 58 days after O 3 fumigation (DAF) at a concentration of 150 mm 3 m -3 (E-O 3 ). At the end of experiment, seedlings were harvested for biomass measurement. E-O 3 caused visible injuries on the mature leaves e.g. necrotic patches and accelerated early defoliation. Relative to the charcoal-filtered air (CF) treatment, E-O 3 significantly decreased shoot and root biomass, pigment content, light-saturated net photosynthesis (P Nsat ), stomatal conductance (g s ), maximum rate of carboxylation (V cmax ) , photochemical quenching coefficient (q p ) and effective quantum yield of PSII photochemistry (Ф PSII ), and also caused a slight reduction in relative increase of basal diameter. Therefore, L. chinense can be assumed to be an O 3 -sensitive tree species, which will be threatened by increasing ambient O 3 concentrations in China.

Impacts of elevated ozone on growth and photosynthesis of Metasequoia glyptostroboides Hu et Cheng

“…Watanabe et al [31] demonstrated that O 3 significantly reduced the V c,max and J max in leaves of beech, but stomatal limitation of photosynthesis was unaffected by O 3 . Similar results were also found in some deciduous and evergreen species such as Liriodendron chinense and Cinnamomum camphora [17,37]. On the other hand, unchanged l accompanied by a decrease in pigments content during the two-year study further confirmed that O 3 -induced the photosynthesis down-regulation was due to nonstomatal factors rather than stomatal closure.…”

“…In general, chronic O 3 exposure resulted in stomatal closure, which is considered as the most important avoidance mechanisms to O 3 stress [17,32] because a decrease in g s protects trees from air pollution by decreasing O 3 uptake [33]. In fact, in this study, leaves exhibited a significant decrease in g s in response to E-O 3 only at the end of the first growing season (Fig.…”

“…However, in some cases, O 3 -induced changes in g s are insufficient to explain the decline in light-saturated photosynthesis (A sat ) [16]. Reductions in A sat have been attributed to decreases in primary carboxylation enzyme Rubisco transcript levels, antioxidant contents and enzyme activity rather than changes in g s [17,18]. A recent study suggests that elevated O 3 induces faster rates of change in photosynthesis rate compared to g s because of the significant decrease in the maximum activity of Rubisco (V c,max ) and maximum electron transport rate (J max ), i.e., O 3 reduces the biochemical capacity to fix CO 2 [19].…”

Concentration- and flux-based ozone dose–response relationships for five poplar clones grown in North China

“…Ozone affects tree health through stomatal uptake, causing visible foliar injury, accelerated leaf senescence, reduced photosynthesis, and impaired stomatal function (Feng et al, 2014;Zhang et al, 2011Zhang et al, , 2014b. The increasing ozone concentration contributes to a decline in forestry productivity linked to economic losses (Felzer et al, 2007;Percy and Karnosky, 2007;Pye, 1988).…”

Structure and function of rhizosphere and non-rhizosphere soil microbial community respond differently to elevated ozone in field-planted wheat

“…Current ambient O 3 levels may cause severe effects on plants, including visible foliar injury or growth reduction, impairment of physiological traits and impacts on resource allocation and reproduction (Paoletti, 2007;Feng et al, 2008;Zhang et al, 2011;Niu et al, 2011;Chen et al, 2008). In recent years, considerable (or increasing) attention has been paid to the below-ground effects of eO 3 (Chen et al, 2009).…”