Annual Progress Report on Malting Barley Research March, 2002

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DEVELOPMENT OF SIX-ROWED MALTING BARLEY GERMPLASM FOR THE
WESTERN US USING CONVENTIONAL AND MARKER-ASSISTED SELECTION
TECHNIQUES
David Hoffman & An Hang
Agricultural Research Service - USDA
National Small Grains Germplasm Research Facility
Aberdeen, Idaho
INTRODUCTION AND OBJECTIVES
Malting barley is an economically important crop in Idaho and in other western states.
The construction of two new malting facilities in southeastern Idaho will significantly
increase the demand for malting barley in the West. The barley improvement program at
Aberdeen, Idaho has, as its primary objective, to develop improved two-rowed and sixrowed
spring and winter malting barley cultivars and germplasm lines adapted to
irrigated and dryland conditions. More emphasis has been placed on irrigated spring
barley. Much progress has been made in the development of two-rowed spring malting
barleys as evidenced by the release of ‘Klages’, ‘Crystal’, and ‘Garnet’ from Aberdeen,
and ‘Crest’, ‘Chinook’, ‘B1202’, and ‘Galena’ from other public and private institutions,
as examples.
The development of spring six-rowed malting barleys for the western U.S. has been more
challenging than that of two-rowed barley. It has been difficult to keep seed yields high
along with acceptable malting quality. Low gains in malting quality may be due to low to
moderate heritabilities of the traits (Foster et al., 1967), and the limitation on sample size
due to the difficulty and cost of malt tests. The problem may lie in the number of genes
controlling these quantitatively inherited traits and the number of segregants required to
combine all of the favorable alleles. Linkage drag and epistatic effects also may interfere
with the desired outcome of high yield and high malting quality. For instance, 'Colter' is a
spring six-rowed malting cultivar that performs very well agronomically in western
irrigated environments (Wesenberg and Burrup, 1998). As for malting quality, Colter is
consistently low in diastatic power (DP), yet has high malt extract levels in most
environments.
Modern molecular techniques have enabled the detailed genetic mapping of several
barley populations (GrainGenes - http://wheat.pw.usda.gov/ggpages/aps.html#barley).
The barley maps have been used for detailed QTL-association studies (Hayes et al.,
1993). Two important genome regions (one on chromosome 1 and the other on
chromosome 4) have been identified in the 'Steptoe'/'Morex' mapping population to have
overlapping alleles for several malting traits and these have been consistent over several
environments (Hayes et al., 1993). Surveys of marker polymorphisms among six-rowed
malting cultivars of the U. of Minnesota breeding program have identified additional
candidate markers/regions for malt quality QTL (Hayes, et al., 1997; Hoffman and
Dahleen, 1997). Alternatively, high grain yield QTL have been transferred from high
yielding two-rowed feed barley 'Baronesse' to two-rowed, malting barley 'Harrington