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Aluminium sulphate restricts migration of Bacillus subtilis in xylem of cut roses: a scanning electron microscope study.

Put, H. M. C.; Klop, W.; Clerkx, A. C. M.; Boekestein, A.;

Scientia Horticulturae Year: 1992 Vol: 51 Issue: 3-4 Pages: 261-274 Ref: 25 ref.

1992

บทคัดย่อ

Aluminium sulphate restricts migration of Bacillus subtilis in xylem of cut roses: a scanning electron microscope study.

Cut flowers of rose cv. Sonia were kept for 4 days in sterile deionized water alone (control) or in sterile deionized water inoculated with 5 x 106 or 5 x 107 cells of B. subtilis/ml. The effects of adding 500 micro g Al2(SO4)3.18H2O/ml and adjusting the vase water pH to 4.0 or 5.0 were studied for inoculated or non-inoculated treatments. Water uptake and flower development were monitored every 24 h. Al2(SO4)3 slightly reduced water uptake and slightly extended the vase life of flowers compared with untreated controls. Al2(SO4)3 showed weak biocidal activity towards B. subtilis at pH less than or equal to 4 but had a negligible effect at pH more than or equal to 5. At pH less than or equal to 4 the Al2(SO4)3 was hydrolysed to give a colloidal Al(OH)3 solution. At pH more than or equal to 5, insoluble colloidal Al(OH)3 was flocculated as a white deposit. Cryo-SEM investigations showed that Al2(SO4)3 and B. subtilis cells added to the vase water had no effect on the ultrastructure of the xylem vessels during the first 48 h of vase life. These studies also showed that B. subtilis cells were co-precipitated with Al(OH)3 on the open surface of cut xylem vessels and acted as a bacterial filter. X-ray microanalysis showed that Al could migrate to a height of 10 cm up cut stems only when the vase water pH was less than or equal to 4.