TITLE

Growth and Leaf Gas Exchange in Three Birch Species Exposed to Elevated Ozone and CO in Summer

AUTHOR(S)
Hoshika, Yasutomo; Watanabe, Makoto; Inada, Naoki; Koike, Takayoshi
PUB. DATE
September 2012
SOURCE
Water, Air & Soil Pollution;Sep2012, Vol. 223 Issue 8, p5017
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We examined the effects of ozone and elevated CO concentration in summer on the growth and photosynthetic traits of three representative birch species in Japan (mountain birch, Monarch birch, and white birch). Seedlings of the three birch species were grown in 16 open-top chambers and were exposed to two levels of ozone (6 and 60 nmol mol for 7 h per day) in combination with two levels of CO (370-380 and 600 μmol mol for daytime) from July to October. No adverse effects of ozone were found in the Monarch birch or the white birch, but elevated ozone in summer reduced branch biomass and net photosynthesis, and accelerated leaf abscission, in the mountain birch. Elevated CO promoted root development and thereby reduced the ratio of shoot dry mass (stem + branch) to root dry mass ( S/ R ratio) in the mountain birch and white birch. In contrast, there was no difference in dry mass between ambient and elevated CO for the Monarch birch, due to downregulation of photosynthesis. Studies of the combined effect of CO and ozone revealed that elevated CO did not ameliorate the effect of ozone on mountain birch in late summer. In considering the ameliorating effect of CO on ozone damage, it is necessary to take account of the species and the season.
ACCESSION #
80028434

 

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