Sensitivity of leaf turgor to air vapour pressure deficit correlates with maximum stomatal conductance

Rodriguez-Dominguez C. M., Hernandez-Santana V., Buckley T. N., Fernandez J. E., Diaz-Espejo A., (2019)

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In Agricultural and Forest Meteorology 272: 156-165 – DOI: 10.1016/j.agrformet.2019.04.006 –

https://www.researchgate.net/publication/332672563_Sensitivity_of_olive_leaf_turgor_to_air_vapour_pressure_deficit_correlates_with_diurnal_maximum_stomatal_conductance

Abstract

Effective study and management of crops and forests would benefit greatly from useful plant-based indicators of the biological controls on evapotranspiration, and particularly stomatal conductance (g s ). Given the strong influence of g s on bulk leaf water potential and turgor pressure (P), in vivo measurement of P may provide useful information about diurnal or seasonal dynamics of g s . Moderate plant water stress affects the diurnal dynamics of P as leaf-to-air vapour pressure deficit (D) varies, and these dynamics correlate to g s . Here, we explored relative changes in P in response to changes in D under mild drought conditions, and how these changes are linked to stomatal behaviour, and specifically to diurnal maximum g s (g s,max ), one of the best indicators of plant water stress. We monitored ecophysiological and environmental variables, as well as a relative proxy for P, during three consecutive seasons in a hedgerow olive orchard where trees were supplied with different irrigation treatments to create well-watered and moderately water-stressed conditions. Our results demonstrated that the sensitivity of P to D correlated well with g s,max reached by the trees within a range in which variations in g s are the main diffusional limitation to photosynthesis. We further showed that this correlation held under a wide range of meteorological conditions and soil water availability. This turgor proxy measurement, which is much easier to measure than g s , can facilitate the use of g s,max as an indicator of plant water stress and evapotranspiration in agriculture and plant science research.

Stomatal responses to leaf turgor

 

 

Most stomatal closure in woody species under moderate drought can be explained by stomatal responses to leaf turgor

by Rodriguez-Dominguez C. M.,

Buckley T. N.,

 Egea G.,

 de Cires A.,

 Hernandez-Santana V.,

 Martorell S.,

 Diaz-Espejo A.

(2016) –

in Wiley Online LIbrary: Browse Accepted Articles
Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future.

DOI: 10.1111/pce.12774

Abstract

Reduced stomatal conductance (g_s) during soil drought in angiosperms may result from effects of leaf turgor on stomata, and/or factors that do not directly depend on leaf turgor, including root-derived abscisic acid (ABA) signals.

To quantify the roles of leaf-turgor-mediated and leaf-turgor-independent mechanisms in g_s decline during drought, we measured drought responses of g_s and water relations in three woody species (almond, grapevine and olive) under a range of conditions designed to generate independent variation in leaf and root turgor, including diurnal variation in evaporative demand and changes in plant hydraulic conductance and leaf osmotic pressure.

We then applied these data to a process-based g_s model and used a novel method to partition observed declines in g_s during drought into contributions from each parameter in the model.

Soil drought reduced g_s by 63-84% across species, and the model reproduced these changes well (r² = 0.91, p < 0.0001, n = 44) despite having only a single fitted parameter.

Our analysis concluded that responses mediated by leaf turgor could explain over 87% of the observed decline in g_s across species, adding to a growing body of evidence that challenges the root-ABA-centric model of stomatal responses to drought.