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

Abstract

a b s t r a c tOne-year-old Metasequoia glyptostroboides seedlings were exposed to non-filtered ambient air (NF) and elevated ozone (E-O 3 , NF + 60 ppb) in open-top chambers for two years. E-O 3 accelerated leaf senescence, as indicated by significant decreases in photosynthetic pigment contents with the elongation of O 3 exposure. E-O 3 significantly affected gas exchange and carboxylation, inducing reductions in light-saturated photosynthesis (A sat ), the maximum activity of Rubisco (V c,max ) and the maximum electron transport rate (J max ). Chl a/b, V c,max /J max and stomatal limitation (l) were not affected. Stomatal conductance (g s ) was significantly decreased by E-O 3 in the first year, but remained unchanged in the second year. It can be inferred that the decrease in A sat by E-O 3 was mainly attributed to the changes in non-stomatal factors. After two years' exposure, E-O 3 caused significant decreases in canopy photosynthesis and leaf mass per area, and a significant increase in the number of branches, but induced slight, not significant decreases in growth and biomass. Therefore, it can be concluded that the carbon accumulation of the species M. glyptostroboides could be negatively affected after long-term exposure to high O 3 concentration.

Ozone exposure- and flux-based response relationships with photosynthesis, leaf morphology and biomass in two poplar clones

“…Numerous studies have shown ozone-induced tree damage, including photosynthesis decrease (Feng et al, 2008b;Pina and Moraes, 2010;Wittig et al, 2007;Zhang et al, 2012), chlorophyll degradation (Calatayud et al, 2011;Zhang et al, 2014) and biomass reduction (Gerosa et al, 2015;Hu et al, 2015;Wittig et al, 2009). In this study, ozone had significant effects on A sat , PhiPS2, chlorophyll content and LMA, which were also significantly different at different times and different clones.…”

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).…”

Elevated CO2 and O3 Levels Influence the Uptake and Leaf Concentration of Mineral N, P, K in Phyllostachys edulis (Carrière) J.Houz. and Oligostachyum lubricum (wen) King f.

“…However, the mechanisms underlying the observed discrepancy in nutrient demand of P. edulis and O. lubricum under elevated CO 2 remain unclear and need further research. Compared to ambient air, elevated O 3 decreased significantly leaf N (−28.9%), P (−31.6%), and K (−29.6%) uptake in P. edulis and N (−25.7%) and P (−25.8%) uptake in O. lubricum (Figure 1), which can be attributed to nutrient-uptake limitation in the plants (including P. edulis and O. lubricum) caused by O 3 -induced plant growth inhibition [5,31]. In addition, the combination of elevated CO 2 and O 3, in comparison with ambient air, significantly decreased P uptake in P. edulis (−13.0%) and N uptake in O. lubricum (−18.3%) (Figure 1).…”

“…These studies have shown that the responses of plant N, P, and K concentrations and uptake to elevated O 3 are more complicated than responses to elevated CO 2 [28,30]. For example, several studies have demonstrated that elevated O 3 decreases N, P, and K concentrations and uptake to some extent due to a reduction in nutrient demand by the plants, caused by O 3 -induced inhibition of plant growth [5,31]. However, other studies have shown either an increase [29] or no change in nutrient concentration and uptake [32][33][34], which have been partly attributed to a defense mechanism against elevated O 3 and an adaptive strategy for plants.…”