The rapid light response of leaf hydraulic conductance: new evidence from two experimental methods

作者：Scoffoni Christine; Pou Alicia; Aasamaa Kroot; Sack Lawren^*

来源：Plant, Cell and Environment, 2008, 31(12): 1803-1812.

DOI：10.1111/j.1365-3040.2008.01884.x

• bundle sheath extensions
• evaporative flux method
• heterobaric
• homobaric
• irradiance
• leaf traits
• rehydration kinetics method

Previous studies have shown a rapid enhancement in leaf hydraulic conductance (K(leaf)) from low to high irradiance (from < 10 to > 1000 mu mol photons m(-2) s(-1)), using the high-pressure flow meter (HPFM), for 7 of 14 tested woody species. However, theoretical suggestions have been made that this response might arise as an artifact of the HPFM. We tested the K(leaf) light response for six evergreen species using refined versions of the rehydration kinetics method (RKM) and the evaporative flux method (EFM). We found new evidence for a rapid, 60% to 100% increase in K(leaf) from low to high irradiance for three species. In the RKM, the leaf rehydration time constant declined by up to 70% under high irradiance relative to darkness. In the EFM, under higher irradiance, the flow rate increased disproportionately to the water potential gradient. Combining our data with those of previous studies, we found that heterobaric species, i.e. those with bundle sheath extensions (BSEs) showed a twofold greater K(leaf) light response on average than homobaric species, i.e. those without BSEs. We suggest further research to characterize this substantial dynamic at the nexus of plant light- and water-relations.

• 出版日期2008-12