Stomatal kinetics and photosynthetic gas exchange along a continuum of iso- to anisohydric regulation of plant water status
Meinzer F. C., Smith D. D., Woodruff D. R., Marias D. E., McCulloh K. A., Howard A. R., Magedman A. L. (2017)
in Plant, Cell &Environment, Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future. –
Species’ differences in the stringency of stomatal control of plant water potential represent a continuum of iso- to anisohydric behavior. However, little is known about how quasi-steady state stomatal regulation of water potential may relate to dynamic behavior of stomata and photosynthetic gas exchange in species operating at different positions along this continuum.
Here we evaluated kinetics of light-induced stomatal opening, activation of photosynthesis and features of quasi-steady state photosynthetic gas exchange in ten woody species selected to represent different degrees of anisohydry.
Based on a previously developed proxy for the degree of anisohydry, species’ leaf water potentials at turgor loss, we found consistent trends in photosynthetic gas exchange traits across a spectrum of iso- to anisohydry.
More anisohydric species had faster kinetics of stomatal opening and activation of photosynthesis and these kinetics were closely coordinated within species. Quasi-steady state stomatal conductance and measures of photosynthetic capacity and performance were also greater in more anisohydric species.
Intrinsic water-use efficiency estimated from leaf gas exchange and stable carbon isotope ratios was lowest in the most anisohydric species. In comparisons between gas exchange traits, species rankings were highly consistent, leading to species-independent scaling relationships over the range of iso- to anisohydry observed.