The Péclet effect on leaf water enrichment correlates with leaf hydraulic conductance and mesophyll conductance for CO₂

Abstract

Leaf water gets isotopically enriched through transpiration, and diffusion of enriched water through the leaf depends on transpiration flow and the effective path length (L). The aim of this work was to relate L with physiological variables likely to respond to similar processes. We studied the response to drought and vein severing of leaf lamina hydraulic conductance (Klamina), mesophyll conductance for CO2 (gm) and leaf water isotope enrichment in Vitis vinifera L cv. Grenache. We hypothesized that restrictions in water pathways would reduce Klamina and increase L. As a secondary hypothesis, we proposed that, given the common pathways for water and CO2 involved, a similar response should be found in gm. Our results showed that L was strongly related to mesophyll variables, such as Klamina or gm across experimental drought and vein-cutting treatments, showing stronger relationships than with variables included as input parameters for the models, such as transpiration. Our findings were further supported by a literature survey showing a close link between L and leaf hydraulic conductance (Kleaf = 31.5 ¥ L -0.43 , r 2 = 0.60, n = 24). The strong correlation found between L, Klamina and gm supports the idea that water and CO2 share an important part of their diffusion pathways through the mesophyll.

Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

“…Interestingly, despite recent findings demonstrating that traits related to leaf hydraulic conductance are positively related to L (Ferrio et al 2012), our non-significant relationships between stem and leaf water isotopic enrichment and leaf morphological traits are contrary to these results since leaf hydraulic conductance and mesophyll conductance might be negatively related to such leaf traits like LMA and TH (Aasamaa et al 2005, Flexas et al 2008. In fact, in cases where water flow is reduced due to tortuous apoplastic pathway, increases in effective L has been observed (Ferrio et al 2009(Ferrio et al , zhou et al 2011.…”

Progress and challenges in using stable isotopes to trace plant carbon and water relations across scales

“…This parameter is especially important for modelling leaf water enrichment in non-steady state. Understanding how the effective length is adjusted by environmental conditions requires knowledge of how water transport inside the leaf is changing, for example, with the leaf's water status (Barbour et al, 2004(Barbour et al, , 2007Ferrio et al, 2009;Kahmen et al, 2009;Ferrio et al, 2012). It is likely that in leaves, all water pools are involved during water transport (Yakir, 1998); however, the leaf water pools might not be considered as perfectly mixed (e.g.…”

Salicylic acid mitigates physiological and proteomic changes induced by the SPCP1 strain of Potato virus X in tomato plants

“…Mesophyll conductance (g m ) was calculated from gas exchange values and fluorescence kinetics as described in Ref. [20]. Measurements were performed at 5, 7, 12 and 14 days post PVX-inoculation (dpi) (Fig.…”