Epidemiolgoy of white rust of rapeseed-mustard in relation to host resistance and environmental interactions

摘要

During three years of artificial screening of large number of Brassica Genotypes against prevalent virulences of Albugo Candida, eleven sources of resistance viz., GSL-1, GSL-1S01, PC-3, PR-8805, HC-1, HNS-2, HNS-4, Midas, Tower, EC-129126-1 and RC-781 were identified with dominant genes for resistance. A prediction equation was developed through multiple regression analysis to account for the effect of different environmental interactions on the periodical and cumulative progression of disease on leaf and staghead phase of ten genotypes. Taking all environmental interaction in to account the cumulative progression of the disease on host leaf could be explained from 82 to 96 per cent. The maximum periodical increase of white rust pustules on host leaf was observed when there was prevalence of 25°C maximum temperature, 10.8°C minimum temperature, >83% relative humidity morning, >73% relative humidity evening and <6.2 h of sunshine. Increase in staghead formation in relation to genotypes and environmental interactions could be predicted up to 92 per cent Maximum periodical increase in staghead formation ws observed when there was 24.4°C maximum temperature, 6.5°C minimum temperature, >87% relative humidity mourning, >39% relative humidity evening and 9.4 h of sunshine.