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Multivariate Evaluation of Isolation Techniques for Fungi Associated With Stored Rapeseed. J. T. Mills, Research Scientist, Agriculture Canada Research Station, Winnipeg, Manitoba, Canada, R3T 2M9; R. N. Sinha(2), and H. A. H. Wallace(3). (2)Principal Research Scientist, Agriculture Canada Research Station, Winnipeg, Manitoba, Canada, R3T 2M9; (3)Adjunct Professor, Department of Agricultural Engineering, University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2. Phytopathology 68:1520-1525. Accepted for publication 31 March 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1520.

A multivariate statistical method was used to evaluate six techniques for isolating seed-borne fungi. The objective was to determine the most reliable mycological isolation technique for fungi known to be actively involved in the deterioration of stored rapeseeds. Analyses were based on examination of 106 samples of Brassica napus ‘Midas’ rapeseed. The seeds were either sound, spoiled, or heated and were obtained from primary elevators across western Canada. Isolation techniques were plain (PA), malt salt (MSA), and Czapek solution (CZA) agars and filter paper soaked with either water (FP), 7.5% salt (SFP), or Czapek (CZFP) solutions. The results of principal component analyses within individual techniques indicated that the FP and SFP techniques provided information on most of the major fungal variables associated with seed deterioration. Because of their simplicity these two techniques together were preferred. The FP-SFP combination was considered superior after interpretation of the results of the principal component analyses of pooled data of the seven combinations of techniques (PA-MSA-CZA-FP-SFP-CZFP, PA-FP, MSA-SFP, CZA-CZFP, FP-SFP-CZFP, PA-MSA-CZA, and FP-SFP). In the PCA of the FP-SFP combination, 52.7% of the variability was accounted by the first, and 13.3% by the second of the principal components. The key fungal variables associated with the first two components were: Aspergillus glaucus, Penicillium spp., and Cladosporium spp. Data on seed germination were obtained from FP but not SFP necessitating the use of both techniques. In the absence of a single technique, the FP-SFP combination appeared to be the most desirable for the mycological study of rapeseeds.

Additional keywords: stored rapeseed, deterioration, fungal pattern, principal component analysis.