Meisha-Marika

For a really great overview on the importance of the circadian clock for understanding seasonal fluxes in CO2 and water vapour in natural settings and for improving crop performance, check out: sciencedirect.com/science/ar… @rescodedios

Don’t discount the circadian clock when it comes to optimising whole-plant physiology for improved crop water-use efficiency!

So what in the model has changed? 1. the isotope effect of decarboxylation during respiration used to feedback on the C pool available for photorespiration. Now the C pools are separated. 2. we changed how you estimate the d13C of the substrate available for respiration. 7/

@FlorianABusch re-derived the original model by Farquhar et al (1982) and found an inconsistency. @GrahamDFarquhar took a look, and the combined result is the newly improved 13C-photosynthetic discrimination model. Those inconsistencies in 13C-gm estimates…gone! 6/

If the two gm estimates between measurements differ, it suggests something is wrong with the model. We did this prev. for the 18O model bit.ly/18Omodel and published today, the results from using a similar technique to investigate the 13C model bit.ly/13Cmodel 4/

If you feed a leaf CO2 gas with two different isotope compositions, the observed discrimination will differ, but the estimated gm shouldn’t change as the inherent physiology remains unaffected by the isotope composition of the source CO2. 3/

THREAD: Modelling photosynthetic isotope fractionation allows us to understand which biochemical & physical traits vary between species & environmental conditions. Not all parameters in the model can be directly measured making validating the model difficult. So how did we do it?

New study led by @_deborahcorso follows up on the relationship between leaf hydraulic conductance and stomatal conductance in wheat during water stress and the results are intriguing! bit.ly/WheatKvul 2/5

In ryegrass, we reported that leaf hydraulic conductance (Kleaf) declined with stomatal conductance when exposed to water stress. This was curious as it went against the idea that stomata close to protect against loss of Kleaf bit.ly/GrassHydraulics 1/5

The role of stomata in preventing desiccation is clearly demonstrated in the latest paper by @LucasCernusak et al. Check out how the humidity inside the leaf drops as VPD increases when stomata can't close!