Genetic resistance to Mycosphaerella pinodes in 558 field pea accessions

Abstract

Comprehensive assessments of germplasm collections of field pea (Pisum sativum L.) have failed to identify any accessions that are highly resistant to Mycosphaerella blight, caused by Mycosphaerella pinodes. In the present study, the broad-sense heritability of resistance to M. pinodes was studied on 558 pea genotypes in a detached-leaf assay and in field trials over 2 yr. In addition, analysis of covariance in disease reaction between the two assessment methods was examined. Only a few genotypes displayed relatively high levels of resistance, and as expected, no complete resistance was observed. The pattern of differences in reaction to M. pinodes among the genotypes demonstrates that resistance is quantitative and moderately heritable. Broad-sense heritability was higher in the detached-leaf assays than in the field trials, likely because of more environmental variance in the field. Covariance between repetitions of the detached leaf assays was not significant but was significant between the field tests. This indicates that detached-leaf assessments are more reliable for assessment of large numbers of accessions. © Crop Science Society of America.