Effects of temperature on the host–pathogen interaction in Ascochyta blight (Ascochyta lentis) of lentil

Abstract

The effects of temperature regimes on the radial growth rate of different isolates of Ascochyta lentis and pathogen virulence and host susceptibility were studied in the laboratory and growth chamber using different pathogen isolates, and lentil genotypes with varying levels of resistance to Ascochyta blight. The growth rate of most isolates increased as temperature increased up to 20°C and declined thereafter. In experiment 1, the highest disease severities were observed on cvs. Laird and Eston and the lowest on ILL5588. Mean disease severities were similar from 10 to 20°C but substantially lower at 25°C for all genotypes except ILL5588. In experiment 2, no significant differences were observed between the two mating types, or in their interactions with genotypes and temperatures. The interactions of genotypes with temperature and with isolates indicated that the relative susceptibility of lentil genotypes depended on temperature and on the isolates of A. lentis. These findings indicated that when temperature changes during epidemic development in the field, different isolates could predominate in the pathogen population at different times.

Keywords:

• lentil
• Ascochyta blight
• temperature
• Ascochyta lentis
• virulence

Acknowledgements

The finical support of the Western Grains Research Foundation, the Saskatchewan Pulse Crop Development Board, and the Natural Sciences and Engineering Research Council of Canada (Research Partnerships Program) is gratefully acknowledged.