ISHS Acta Horticulturae 181: III International Symposium on Postharvest Physiology of Ornamentals
EXPERIMENTALLY INDUCED PLUGGING OF CUT-ROSE XYLEM BY PARTICULATE OR MACROMOLECULAR MATTER |
| Authors: | H.C.M. de Stigter, A.G.M. Broekhuysen |
| Abstract:
Macromolecules of sufficient size and particulate matter small enough to enter cut xylem vessels will plug stems if taken up in sufficient quantity along with the transpiration stream of water. Apart from toxic and/or other effects, bacteria may do the same by their mere physical presence and dimensions. Here, we report some results obtained with a model system involving cut roses treated with water-colour suspensions, or with polyethylene glycol (PEG) or dextran (D) of various molecular weights (PEG, 0.2 – 40 x 103; D, 4 – 2000 x 103). Plant reactions studied, involving water turnover and diurnal and long-term fresh weight changes, ranged from almost instantaneous collapse (higher concentration, higher molecular weight) to complete tolerance (lower concentration, lower molecular weight). The range of concentrations between damaging and non-damaging effects appears to be rather narrow for particulate matter. The precipitate forming in vase-water formulas containing aluminium salts is harmless. Both particulate suspensions and macromolecular solutions cause more acute effects when treatments start in the light, with plants actively transpiring, than in the dark, with stomates closed. | |
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