Genetic Improvement in Malting Barley Cultivars Since 19201

Abstract

The constraints imposed by the requirement of acceptable malting and brewing quality in new barley(Hordeum vulgare L.) cultivars, and the resultant use of a narrow germplasm base make the genetic gains in breeding of Midwestern malting barleys of special interest. In this study cultivars which have dominated the malting barley acreage in the tri‐state area of Minnesota and North and South Dakota since 1920 were evaluated to determine the amount of genetic gain which has been made in yield, agronomic and quality traits. Six cultivars were evaluated for 18 traits in seven trials conducted at Crookston and St. Paul, Minn. during the years 1978 to 1982. Four of the six cultivars—‘Kindred’ ‘Traill,’ ‘Larker,’ and ‘Morex’—were in turn the dominant cultivar in the tri‐state malting barley area. Cultivars differed significantly for 15 of the 18 traits. Grain yield of Morex was 51% greater than that of ‘Manchuria,’ the oldest cultivar; the average annual increase in grain yield measured from Manchuria to Morex was 0.9%. However, regression analysis indicates that for the past 40 years, the time period in which serious breeding efforts have been made in the tri‐state area, yield gains have been nearly linear with an average annual increase of 2%.During this time grower yields have nearly doubled and 73% of this increase can be attributed to improved cultivars or genetic improvement. Increases in grain yield of the cultivars were attributed to improvements in lodging resistance, an increase in harvest index( HI) from 0.31 to 0.40, and increases kernel weight and spike number. Significant improvements were achieved for plump kernels, malt extract, alpha amylase, diastatic power and disease resistance. Nitrogen harvest index also was higher in the newer cultivars. The results indicate that sizable yield gains, as well as gains for other traits, can be made within a relatively narrow germplasm base.