Effect of cultivar and strain interactions in the screening of resistance against wheat scab caused by Fusarium graminearum

Factorial experiments were carried out in the field at the campus of Universite Laval in 1991 and 1992, and Saint-Louis-de-Pintendre station in 1992 and 1993. The objective was to specify if wheat scab development caused by Fusarium graminearum is significantly affected by cultivar x strain interactions. Eleven wheat (Triticum aestivum) cultivars and one triticale (x Triticosecale) cultivar representing the range of sensitivity to this disease in Quebec were inoculated with nine strains of F. graminearum, Significant interactions between cultivars, strains and environments were shown by the results of a combined analysis of variance. Cultivar x strain and cultivar x environment interactions explained a small proportion of the total sum of squares and did not have a strong impact on cultivar average ranking by environment or strain. However, the examination of cultivar x strain interactions revealed that the rank of cultivars such as Casavant and Concorde changed when different strains were compared. This research shows for the first time that all interactions involving cultivars, strains and environments have a similar impact on wheat scab resistance screening.