Resistance to Finnish net blotch and scald isolates in barleys bred for Latin America

Abstract

Seedlings of 214 barley (Hordeum vulgare L.) accessions were screened in the greenhouse for resistance to net blotch (Pyrenophora teres Drechs. f. teres Smedeg.). A further 83 accessions were similarly screened for resistance to scald (Rhynchosporium secalis (Oud.) J.J. Davis). Infection responses (IR) on the first and second seedling leaves were monitored in both trials. There were statistically significant correlations between IRs scored on the first two seedling leaves for both diseases, indicating that in screening seedlings in the greenhouse under artificially created epidemics, symptom scores on the first leaf are sufficient for indicating relative levels of resistance. Both trials included selected Nordic barley genotypes, and barleys constituting differential series including known sources of resistance, in addition to accessions bred specifically for areas in Latin America where the diseases are prevalent. The Nordic cultivars were universally highly susceptible to the two pathogens, but over 80% of the accessions in each nursery were resistant to the respective diseases. These resistant accessions, which represent a range of agronomic types, may be useful to Finnish barley breeders for improving the resistance status of barleys.