title: Species characteristics and intraspecific variation in growth and photosynthesis of Cryptomeria japonica under elevated O3 and CO2.
abstract: In order to predict the effects of future atmospheric conditions on forest productivity, it is necessary to clarify the physiological responses of major forest tree species to high concentrations of ozone (O3) and carbon dioxide (CO2). Furthermore, intraspecific variation of these responses should also be examined in order to predict productivity gains through tree improvements in the future. We investigated intraspecific variation in growth and photosynthesis of Cryptomeria japonica D. Don, a major silviculture species in Japan, in response to elevated concentrations of O3 (eO3) and CO2 (eCO2), separately and in combination. Cuttings of C. japonica were grown and exposed to two levels of O3 (ambient and twice-ambient levels) in combination with two levels of CO2 (ambient and 550 µmol mol-1 in the daytime) for two growing seasons in a free-air CO2 enrichment experiment. There was no obvious negative effect of eO3 on growth or photosynthetic traits of the C. japonica clones, but a positive effect was observed for annual height increments in the first growing season. Dry mass production and the photosynthetic rate increased under eCO2 conditions, while the maximum carboxylation rate decreased. Significant interaction effects of eO3 and eCO2 on growth and photosynthetic traits were not observed. Clonal effects on growth and photosynthetic traits were significant, but the interactions between clones and O3 and/or CO2 treatments were not. Spearman's rank correlation coefficients between growth traits under ambient conditions and for each treatment were significantly positive, implying that clonal ranking in growth abilities might not be affected by either eO3 or eCO2. The knowledge obtained from this study will be helpful for species selection in afforestation programs, to continue and to improve current programs involving this species, and to accurately predict the CO2 fixation capacity of Japanese forests.
authors.affiliation: Forest Tree Breeding Center (FTBC), Forestry and Forest Products Research Institute (FFPRI), 3809-1 Ishi, Juo-cho, Hitachi, Ibaraki 319-1301, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Hiraoka
authors.affiliation: Tohoku Regional Breeding Office, FTBC, FFPRI, 95 Osaki, Takizawa, Iwate 020-0621, Japan.
authors.forename: Taiichi
authors.initials: T
authors.lastname: Iki
authors.affiliation: Forest Tree Breeding Center (FTBC), Forestry and Forest Products Research Institute (FFPRI), 3809-1 Ishi, Juo-cho, Hitachi, Ibaraki 319-1301, Japan.
authors.forename: Mine
authors.initials: M
authors.lastname: Nose
authors.affiliation: FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tobita
authors.affiliation: FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yazaki
authors.affiliation: Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-8580, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Fujisawa
authors.affiliation: Hokkaido Research Center, FFPRI, 7 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8516, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Kitao
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D032485:Cryptomeria / Q000254:growth & development* / Q000502:physiology*; D007564:Japan; D010126:Ozone / Q000032:analysis*; D010641:Phenotype; D010788:Photosynthesis
chemical_list: D002245:Carbon Dioxide; D010126:Ozone
keywords: Cryptomeria japonica; O3 sensitivity; interaction of clones and treatments; intraspecific variation