Revisiting the carbon isotope discrimination and water use efficiency relation: the influence of mesophyll conductance

摘要: SummaryThe carbon isotope discrimination (Δ) has been used widely to infer intrinsic water-use efficiency (iWUE) of C3 plants, a key parameter linking and water fluxes. Despite the essential role mesophyll conductance (gm) in photosynthesis Δ, its effect on Δ-based predictions iWUE generally neglected.Here, we derive mathematical expression as function Δ that includes gm (iWUEmes) exploits gm-stomatal (gsc) relationship across drought-stress levels plant functional groups (deciduous or semi-deciduous woody, evergreen woody herbaceous species) global database. iWUEmes was further validated with an independent dataset online-Δ CO2 H2O gas exchange measurements seven species.Drought stress reduced gsc by 52% 45% averaged over all groups, but had no significant gsc/gm ratio, suggesting well-constrained ratio 0.79±0.07 (95%CI, n=198) treatments. Due part synchronous behavior gm, negatively correlated iWUE. Incorporating model significantly improved estimation compared simple model.The inclusion effects, even using fixed 0.79 when is unknown, proved desirable eliminate bias estimating from various vegetation types.Competing Interest StatementThe authors have declared competing interest.View Full Text