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

Abstract

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 for 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 discoloration and in incidence and severity of infection. The most common symptom associated with infection by this pathogen is red smudge, a pink to bright red discoloration. This developed in all Canada Western Amber Durum cultivars but was less apparent in the Canada Western Red Spring cultivars. Other common symptoms observed in all cultivars were black point, dark smudge, and specks. Some differences in the incidence and severity of the discoloration among cultivars appeared to be related to seed colour. The white-seeded cultivars, regardless of quality class, were in general more susceptible than the red-seeded cultivars. However, there were also differences in the predominant type of symptom and in the incidence and severity of infection among and within classes that were not related to seed colour. It was concluded that the type of symptom, and its incidence and severity, are mostly genotype-dependent and only partially conditioned by seed colour or wheat quality class or species.