Increased concentrations of ABA may augment stomatal responsiveness to low VPD.

 

Stomatal response of an anisohydric grapevine cultivar to evaporative demand, available soil moisture and abscisic acid.

by Rogiers S. Y., Greer D. H., Hatfield J. M., Hutton R. J., Clarke S. J, Hutchinson P. A., Somers A. (2012)

 

in Tree Physiol. 32(3): 249-261 – DOI: https://doi.org/10.1093/treephys/tpr131 –

(CrossRef,Medline) – 

https://academic.oup.com/treephys/article-lookup/doi/10.1093/treephys/tpr131

 

Abstract

Stomatal responsiveness to evaporative demand (air vapour pressure deficit (VPD)) ranges widely between species and cultivars, and mechanisms for stomatal control in response to VPD remain obscure. The interaction of irrigation and soil moisture with VPD on stomatal conductance is particularly difficult to predict, but nevertheless is critical to instantaneous transpiration and vulnerability to desiccation.

Stomatal sensitivity to VPD and soil moisture was investigated in Semillon, an anisohydric Vitis vinifera L. variety whose leaf water potential (Ψl) is frequently lower than that of other grapevine varieties grown under similar conditions in the warm grape-growing regions of Australia.

A survey of Semillon vines across seven vineyards revealed that, regardless of irrigation treatment, midday Ψl was dependent on not only soil moisture but VPD at the time of measurement. Predawn Ψl was more closely correlated to not only soil moisture in dry vineyards but to night-time VPD in drip-irrigated vineyards, with incomplete rehydration during high night-time VPD.

Daytime stomatal conductance was low only under severe plant water deficits, induced by extremes in dry soil. Stomatal response to VPD was inconsistent across irrigation regime; however, in an unirrigated vineyard, stomatal sensitivity to VPD—the magnitude of stomatal response to VPD—was heightened under dry soils.

It was also found that stomatal sensitivity was proportional to the magnitude of stomatal conductance at a reference VPD of 1kPa. Exogenous abscisic acid (ABA) applied to roots of Semillon vines growing in a hydroponic system induced stomatal closure and, in field vines, petiole xylem sap ABA concentrations rose throughout the morning and were higher in vines with low Ψl.

These data indicate that despite high stomatal conductance of this anisohydric variety when grown in medium to high soil moisture, increased concentrations of ABA as a result of very limited soil moisture may augment stomatal responsiveness to low VPD.

Advertisements

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s