Publications by authors named "Karen E Loucos"
H O enrichment develops when leaves transpire, but an accurate generalized mechanistic model has proven elusive. We hypothesized that leaf hydraulic architecture may affect the degree to which gradients in H O develop within leaves, influencing bulk leaf stable oxygen isotope enrichment (Δ ) and the degree to which the Péclet effect is relevant in leaves. Leaf hydraulic design predicted the relevance of a Péclet effect to Δ in 19 of the 21 species tested.
View Article and Find Full Text PDFArticle Synopsis
- Stomata act as a resistor in the series of resistances for carbon and water exchange between leaves and the atmosphere, with mesophyll conductance (g) and leaf hydraulic conductance (k) being additional factors.
- Recent studies indicate that g and k might be coordinated across different species due to common pathways.
- In cotton, a weak correlation between g and k was noted under growth conditions, but g showed independent regulation from short-term environmental changes and was notably reduced at high CO levels.
Article Synopsis
- Researchers are increasingly interested in using gas-exchange systems and laser isotope measurement to study plant water dynamics under non-steady-state (NSS) conditions, which evaluate isotopic variations in leaf water and transpiration.
- The existing Farquhar & Cernusak (F&C) NSS model, designed for open fields, does not work well in gas-exchange cuvettes due to its assumption of constant water vapor isotope composition, necessitating modifications for accurate application.
- The new model introduces a 'net-flux' approach to leaf water turnover, aligning well with experimental data from cotton leaves and suggests that this revised model should be adopted for future cuvette-based isotope studies.
Article Synopsis
- The two-pool and Péclet effect models are theories aimed at understanding how leaf water oxygen isotope composition is influenced at the whole-leaf level.
- Researchers measured the oxygen isotopic composition of transpiration and transpiration rate in 61 cotton leaves using advanced spectrometry techniques.
- Results showed that the two-pool model effectively predicts leaf water enrichment, indicating that it may be a simpler and adequate approach for ecological isotopic studies.
Stable oxygen isotope techniques may be a useful tool to investigate the pathways of water movement within leaves. However, implementation of such methods is limited due to uncertainty in the effective path length (L) for the Péclet effect in leaf water enrichment models. Previous studies have found relationships between L and physiological parameters such as transpiration rate (E) and leaf hydraulic conductance (k(leaf)) both within and between species.
View Article and Find Full Text PDF