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- Title
Vigour reduction in girdled peach trees is related to lower midday stem water potentials.
- Authors
Tombesi, Sergio; Day, Kevin R.; Johnson, R. Scott; Phene, Rebecca; DeJong, Theodore M.
- Abstract
Stem or trunk girdling is a technique used in physiological studies and in horticultural practice for interrupting carbon flow through the phloem to other parts of the plant without influencing water flow in the xylem. Trunk girdling in peaches is practiced primarily to stimulate fruit growth but it also tends to decrease shoot vigour for a period of time after girdling. Water flow through the trunk or branches of peach trees is thought to be primarily dependent on the most recently formed ring of xylem and vegetative growth is closely related to stem water potential and stem hydraulic conductance. The aim of the present work was to determine whether vigour reduction due to girdling was correlated with a reduction in midday stem water potential during the period of time between girdling and the subsequent healing of stem tissue. 'Springcrest' peach trees were girdled on two different dates. Fruit yield and size, water sprout growth, proleptic shoot growth and stem water potential were measured. Early and late girdled trees yielded larger fruits and fewer and shorter water sprouts in comparison with control trees. Midday stem water potential declined significantly after girdling and gradually recovered until the time of fruit harvest. These results suggest that the vigour reduction of girdled trees is related to a decrease of midday stem water potential caused by girdling. Early tree girdling increased the reduction in midday stem water potential and shoot growth compared with the later girdling treatment. These results point out that even though girdling only removes bark and phloem tissue it can apparently affect water flow in xylem. Trunk girdling (horticultural practice used to increase fruit size) reduces vegetative shoot growth although there appears to be higher availability of carbohydrates above the girdle in girdled trees. This research indicates that early spring scaffold girdling decreased stem water potential above the girdle suggesting that early spring girdling not only influences phloem flow (that is interrupted by girdling) but also decreases xylem flow. The decreased stem water potentials appear to be directly related to reductions in vegetative shoot growth and explain why early spring girdling reduces shoot growth. It is hypothesized that early spring girdling affects xylem flow because the girdling process interrupts cambial activity and the production of new xylem however girdling may also influence root activity.
- Subjects
TREE girdling; PEACH; FRUIT development; TREE growth; XYLEM; PLANT water requirements
- Publication
Functional Plant Biology, 2014, Vol 41, Issue 12, p1336
- ISSN
1445-4408
- Publication type
Article
- DOI
10.1071/FP14089