Reaction of common and durum wheat cultivars to infection of kernels by Pyrenophora tritici-repentis

Kernel discoloration caused by Pyrenophora tritici-repentis (Died.) Drechs. is an important downgrading factor in wheat. Twenty-nine durum and common wheat cultivars belonging to four different quality classes were compared f or their reaction to inoculation of kernels with P. tritici-repentis under controlled conditions. All cultivars were susceptible to this pathogen but they differed in the predominant type and (or) intensity of kernel discolor ation and in incidence and severity of infection. The most common symptom a ssociated with infection by this pathogen is red smudge, a pink to bright r ed discoloration. This developed in all Canada Western Amber Durum cultivar s but was less apparent in the Canada Western Red Spring cultivars. Other c ommon symptoms observed in all cultivars were black point, dark smudge, and specks. Some differences in the incidence and severity of the discoloratio n among cultivars appeared to be related to seed colour. The white-seeded c ultivars, regardless of quality class, were in general more susceptible tha n the red-seeded cultivars. However, there were also differences in the pre dominant type of symptom and in the incidence and severity of infection amo ng and within classes that were not related to seed colour. It was conclude d that the type of symptom, and its incidence and severity, are mostly geno type-dependent and only partially conditioned by seed colour or wheat quali ty class or species.