The effects of ozone on growth and stomatal response in the F₂ generation of hybrid poplar (Populus trichocarpa × Populus deltoides)

Abstract

Thirty-six F 2 hybrid poplar (Populus trichocarpa × P. deltoides) clones were fumigated with ozone to record its effects on growth, correlate them with stomatal response and screen for ozone sensitivity. Fumigation was applied for 6 to 9 h each day for approximately 3 months at ozone concentrations of 85 to 128 µg g -1 using open-top chambers. Height, diameter, number of leaves, stomatal conductance, transpiration rate, total biomass, biomass components and root/shoot ratios were reduced by ozone stress. Percent of leaf fall in ozone-treated plants was nearly three times higher than in control plants exposed to charcoal-filtered air. Leaf senescence, because of ozone exposure, did not appear to be associated with reduced biomass production. Some clones had a high percentage of leaf-fall with ozone exposure, but were able to maintain total biomass production near that of the control. Their response may be an example of an ability to adjust or compensate for ozone damage. There was no significant or consistent relationship between stomatal conductance and total biomass or the change in stomatal conductance as a result of ozone exposure and the change in total biomass. Taken together, these results suggest that effects of ozone on poplar growth cannot be solely correlated to changes in stomatal conductance, more physiological and biochemical parameters should be examined.Additional key words: leaf senescence, open top chamber, relative growth rate, stomatal conductance, transpiration rate.

The physiological, transcriptional and genetic responses of an ozone- sensitive and an ozone tolerant poplar and selected extremes of their F 2 progeny

“…In contrast, some genotypes had over 90% damaged leaves later in the season. The marked increase in leaf abscission is consistent with previous work (Bohler et al, 2007;Karnosky et al, 1996;Woo and Hinckley, 2005), and serves to demonstrate the detrimental effect of ozone on leaf biomass. The treatment specific co-location of QTL for leaf number, leaf abscission and visible leaf damage with basal diameter suggests that these may be the responses resulting in reduced diameter growth.…”

“…No significant ozone effect on height was found but in contrast for basal stem diameter a small (À3.2%) but significant negative effect (F 1,132 ¼ 11.24, p < 0.001) of ozone was found similar to that reported in a meta-analysis of forest tree ozone responses (Wittig et al, 2009), indicating that ozone exposure is likely to impact biomass yield. This will require further confirmatory analysis from longer-term studies, but suggests that Populus biomass yield is likely to be detrimentally affected by future increased ozone concentrations, which are consistent with previous reports (Bohler et al, 2007;Bortier et al, 2000;Karnosky et al, 1996;Wittig et al, 2009;Woo and Hinckley, 2005). Such decreases in productivity are likely to be related to decreased photosynthetic activity (Bortier et al, 2000;Coleman et al, 1995;Degl'Innocenti et al, 2007;Lorenzini et al, 1999) and reduced leaf area (Wittig et al, 2009).…”

Effects of elevated atmospheric CO2 and tropospheric O3 on nutrient dynamics: decomposition of leaf litter in trembling aspen and paper birch communities

“…Calcium transport is considered to be governed by transpiration (McLaughlin and Wimmer 1999). Elevated O 3 has been shown to decrease transpiration rates (Woo and Hinckley 2005;Moraes et al 2004), which may have contributed to the decreased Ca accumulation in leaf litter reported here.…”

Changes in effects of ozone exposure on growth, photosynthesis, and respiration of Ginkgo biloba in Shenyang urban area

“…Visible injury has been the criterion used in many interspecies comparisons (Donnelly et al 2001, Woo andHinckley 2005). The O 3 -specific visible injuries were mainly light-brown flecks, which have previously been identified by Bungener et al (1999) and Bassin et al (2004).…”