Xylem plugging and postharvest longevity of cut Acacia holosericea

Ratnayake, K., Joyce, D. C. and Webb, R. I. (2015) Xylem plugging and postharvest longevity of cut Acacia holosericea. Acta Horticulturae, 1104 287-293. doi:10.17660/ActaHortic.2015.1104.44

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Author Ratnayake, K.
Joyce, D. C.
Webb, R. I.
Title Xylem plugging and postharvest longevity of cut Acacia holosericea
Formatted title
Xylem plugging and postharvest longevity of cut Acacia holosericea
Journal name Acta Horticulturae   Check publisher's open access policy
ISSN 0567-7572
ISBN 9789462610903
Publication date 2015-01-01
Sub-type Article (original research)
DOI 10.17660/ActaHortic.2015.1104.44
Open Access Status Not Open Access
Volume 1104
Start page 287
End page 293
Total pages 7
Place of publication Leuven, Belgium
Publisher International Society for Horticultural Science
Language eng
Formatted abstract
An inherently short vase life is a problematic characteristic of cut flowers and foliage for otherwise attractive native Australian Acacia spp. Reasons underlying the poor postharvest water uptake of cut acacia stems have been elusive. A. holosericea was used to investigate possible bacteria-induced and wound-induced xylem occlusion. The effects of bacterial- and wound-induced xylem blockage on water uptake were investigated by light and scanning and transmission electron microscopy. Observations were made on cut stems that stood into either deionised water (DIW; control) or 0.5 mM Cu2+ solution and on stems pulsed with 2.2 mM Cu2+ solution and then stood into DIW. The stem-end region of cut A. holosericea that stood into DIW or Cu2+ solution became covered with bacterial growth after 3 days. Regardless of the bacterial biofilm, the Cu2+ treated stems had improved water relations and vase life. Therefore, the biofilm had little or no effect on cut A. holosericea longevity. Further observations revealed presence of a vessel-occluding substance (gel) originating from axial parenchyma cells in direct physical contact with xylem vessels. The gel exuded into vessel lumens through pit membranes, evidently as a wound-response. Xylem occlusion by gels in A. holosericea may be especially problematic due to an abundance of secretory contact cells relative to xylem elements. Nonetheless, active wound response processes may be the key determinant of short postharvest longevity for this and possibly other cut Acacia spp. Cu2+ treatments, however, disrupted the secretory function of axial parenchyma cells thereby preventing vessel occlusion by the gels.
Keyword Acacia
Cut Foliage
Electron microscopy
Vase Life
Water uptake
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ
Additional Notes Originally presented at the XXIX International Horticultural Congress: IHC2014 held in Brisbane 17-22 August 2014

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2016 Collection
Centre for Microscopy and Microanalysis Publications
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