Changes in resistance to powdery mildew in a barley composite cross

摘要

The response of barley composite cross XLII to selection for resistance to powdery mildew was evaluated. Representative samples from eight cycles of recurrent selection were inoculated with two isolates ofErysiphe graminisf.sp.hordei. Frequencies of resistant plants were determined for each cycle. The resistance in composite cross XLII increased with selection. Increased selection pressure in 1986 resulted in a more rapid increase in resistance than in previous years. Multiple alleles occurring in theMl-alocus did not seem to have a negative effect on the accumulation of resistance in composite cross XLII.Key words:Hordeum vulgare, barley,Erysiphe graminisf.sp.hordei, powdery mildew, response to selection, recurrent selection.