Abstract

The primary function of stomata is to minimize plant water loss while maintaining CO2 assimilation. Stomatal water loss incurs an indirect cost to photosynthesis in the form of non-stomatal limitations (NSL) via reduced carboxylation capacity (CAP) and/or mesophyll conductance (MES). Two optimal formulations for stomatal conductance (g(s)) arise from the assumption of each type of NSL. In reality, both NSL could coexist, but one may prevail for a given leaf ontogenetic stage or plant functional type, depending on leaf morphology. We tested the suitability of two g(s) formulations (CAP versus MES) on species from six plant functional types (C-4 crop, C-3 grass, fern, conifer, evergreen, and deciduous angiosperm trees). MES and CAP parameters (the latter proportional to the marginal water cost to carbon gain) decreased with water availability only in deciduous angiosperm trees, while there were no clear differences between leaf ontogenetic stages. Both CAP and MES formulations fit our data in most cases, particularly under low water availability. For ferns, stomata appeared to operate optimally only when subjected to water stress. Overall, the CAP formulation provided a better fit across all species, suggesting that sub-daily stomatal responses minimize NSL by reducing carboxylation capacity predominantly, regardless of leaf morphology and ontogenetic stage.

Keywords

Drought; fern; mesophyll conductance; ontogeny; optimization; photosynthesis; plant functional type; stomatal conductance; transpiration; water use efficiency

Published in

Journal of Experimental Botany
2019, Volume: 70, number: 5, pages: 1639-1651
Publisher: OXFORD UNIV PRESS

SLU Authors

• Saavedra Berlanga, Noelia

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • National Institute of Agricultural Research (INRA)

UKÄ Subject classification

Botany


Publication identifier

DOI: https://doi.org/10.1093/jxb/erz020

Permanent link to this page (URI)

https://res.slu.se/id/publ/99272