Annals of Botany

Concurrent measurements of stomatal conductance, sap pH and hydraulic conductance in Eucalyptus globulus clones

Selected Eucalyptus globulus clones can grow to a height of up to 14m in 3 years, receiving an average rainfall of 630 mm year–1 with a 4-month summer drought. Working with plants under a year old from five clones, Hernández et al. found that xylem sap pH decreased as water potential and stomatal conductance decreased under increasing vapour pressure deficits.

Eucalyptus globulus
Eucalyptus globulus. Photo: Joan Simon / Flickr.

Stomata closed after a significant amount of hydraulic conductance was lost, but precluded water potential from decreasing below –1.8MPa. These results suggest a coordinated response aimed at preserving the hydraulic sufficiency of the stem and resulting in sap acidification.

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