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Assessment of resistance to Plasmodiophora brassicae in swedes
Author(s) -
WILLIAMSON CYNTHIA J.
Publication year - 1987
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.1987.tb02234.x
Subject(s) - biology , seedling , cultivar , inoculation , shoot , gall , spore , population , horticulture , agronomy , dry weight , pathogen , botany , immunology , demography , sociology
A method is described in which swede seedlings inoculated with standardized concentrations of resting spores of specific populations of Plasmodiophora brassicae can be evaluated for resistance in different environments. Similar ranking for resistance of four swede cultivars inoculated with one pathogen population was obtained from seedling tests in a glasshouse, from young plants in a polythene tunnel, and from mature plants in field trials. Differential resistance of the four cultivars to two pathogen populations evident in glasshouse seedling tests was more clearly demonstrated in the field where there was a highly significant cuitivar × pathogen population interaction (p<0 001) for both root fresh weight and mean disease category. The inclusion of uninoculated control plants in field trials enabled a direct comparison of yield with that from inoculated plants. Cultivars were defined as resistant in terms of yield if they did not suffer any crop loss in comparison with uninoculated plants, even though some plants showed restricted gall development. The distribution of fresh weight to galls, roots and shoots could be used to characterize the relative resistance of cultivars; in the most susceptible cultivars there was rapid gall development but little increase in root or shoot fresh weight between 6 and 12 weeks after inoculation. Differential response was determined during the 6 weeks following inoculation; the implications of this observation are discussed in relation to growth stage and rate of development of host and pathogen.