The Effect of Axis Splitting on Xylem Pressure Potentials and Water Movement in the Desert Shrub Ambrosia dumosa (Gray) Payne (Asteraceae)

Publisher Website
Google Scholar
Abstract
Predawn xylem pressure potential (XPP) measurements were used to investigate the effects of axis splitting on water relations of the Mojave Desert [California, USA, sites] shrub A. dumosa. Differences among branches within shrubs were significant in all large shrubs with split axes at least once during the summer but not in intermediate or small shrubs with unsplit axes. A subset of plants received 24 l of water delivered to one side of the plants from buckets every other week during the summer. Two of 3 large, watered shrubs showed significant differences among branches at least once during the summer, but XPP were not higher than in unwatered shrubs. No significant differences among branches of intermediate and small, watered shrubs occurred; both intermediate and small shrubs, however, showed increased XPP and produced small, leafy, terminal shoots in response to being watered. The pathway of water movement was investigated with a dye that ascended sectorially in all plants.