title: Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan.
abstract: Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578, Japan. osadada@kais.kyoto-u.ac.jp
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Osada
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Onoda
authors.forename: Kouki
authors.initials: K
authors.lastname: Hikosaka
mesh_terms: D000388:Air / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D017753:Ecosystem; D045482:Hot Springs; D007564:Japan; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D028502:Polygonum / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D013472:Sunlight
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D009584:Nitrogen