Effect of wheat seed colour on the incidence and severity of red smudge and black point caused by Pyrenophora tritici-repentis

Abstract

Pyrenophora tritici-repentis (Died.) Drechs. (anamorph Drechslera tritici-repentis (Died.) Shoemaker) causes red smudge, black point and dark smudge (Fernandez et al., 1998; 2001; Francl and Jordahl, 1993). This discoloration could result in downgrading due to low tolerance levels in the top grades (Canadian Grain Commission, 1994). Incorporation of disease resistance into all wheat classes would therefore be of economic benefit to producers. Fernandez et al. (2001) determined that cultivars in all four wheat quality classes tested were susceptible to P. tritici-repentis but that they differed in the predominant type and/or intensity of the discoloration and in incidence and severity of the infection. Some of the differences in the incidence and severity of the discoloration among cultivars appeared to be related to seed colour. Because there were differences also within classes not related to seed colour, the impact of seed colour per se on the development of kernel discoloration caused by P. tritici-repentis could not be accurately assessed. The objective of this study was to assess the incidence and severity of kernel discoloration caused by P. tritici-repentis in near-isogenic lines for seed coat colour so that genotypic effects could be separated from seed colour.