Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA.
Ann Bot. 2013 Sep;112(5):911-8. doi: 10.1093/aob/mct143. Epub 2013 Jul 16.
Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status.
Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming.
In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility.
Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change.
在许多物种中,叶片水力特性与蒸腾作用和光合作用密切相关。然而,目前尚不清楚气体交换和水力特性是否会对气候变化做出协调一致的响应。本研究的目的是研究与环境水平相比,在升高的[CO2]和温度下生长时,大豆叶片水力导度(Kleaf)对叶片气体交换和叶片水分状况的响应。
通过两个控制环境生长室实验,测量大豆在升高的[CO2]和温度下生长时的 Kleaf、气孔导度(gs)和光合作用(A)。这些结果通过在自由空气升高[CO2](FACE)和冠层增温下生长的大豆田间实验进行了验证。
在室研究中,Kleaf 并没有适应升高的[CO2]生长,尽管气孔导度下降,光合作用增加。在升高的温度下生长也不会影响 Kleaf,尽管 gs 和 A 表现出显著但不一致的下降。在 FACE 设施中,对田间生长的大豆进行的研究证实,室培养植物对增加的[CO2]和温度生长的 Kleaf 没有反应。
尽管 gs 如先前报道的那样对[CO2]和升高的温度做出了响应,但大豆叶片水力和叶片气体交换对这两个气候变化因素的响应并没有很强的联系。这种不同的行为可能导致在极端环境条件下,水力供应和蒸腾需求之间出现不平衡,随着全球气候继续变化,这种不平衡可能会变得更加普遍。