Major market classes of soft wheat grown in the Northwestern USA are soft white club and soft white common. Club cultivars have the C allele for dense spike while common cultivars have the c allele for lax spike. As a group club cultivars generally have superior milling and baking quality than common cultivars. In contrast common cultivars usually have higher test weight and grain yield potentials than club cultivars. The objective of this study was to determine if quality and agronomic trait differences between club and lax spike nearly isogenic lines (NILs) are directly associated with the C locus.
Material and methods
Four pairs each of NILs having either the C allele for dense spike or the c allele for lax spike were developed in two populations. The populations were Early Blackhull/7*Paha and Suweon 185/7*Paha. Paha is a soft white winter dub cultivar and was the source of the C allele in both populations. Sources of the c allele were Early Blackhull, a hard red winter cultivar and Suweon 185 a soft red winter breeding line from South Korea. The NILs with either the C or c allele were selected in the F4 generation after six backcrosses to Paha.
Agronomic data was obtained on eight traits in 6 to 7 trials for the Early Blackhull/7*Paha NILs during 1995 and 1996 and from 6 to 12 trials for the Suweon 185/7*Paha NILs during 1994 to 1996. Trials comprised three eastern Washington environments differing in growing degree days, cropping systems and moisture availability. Each trial consisted of a single replication of the NILs and Paha. Analyses of variance were performed across trials for each trait. The four NILs of each spike density type did not differ significantly among each other for any of the eight traits. Hence data was pooled across the club NILs and the lax NILs.
Quality data was obtained from three trials each in 1995 and 1996. A single 250 g sample of the NILs and Paha from each trial was analyzed for 13 quality traits. They were flour yield, break flour yield, kernel hardness, wheat protein, flour protein, flour ash, milling score, mixograph absorption, mixing type, cookie diameter, cookie top grain score, sponge cake volume, and score. Methods for evaluating these traits are described by the American Association of Cereal Chemists (1995). The data was analyzed for each year and across both years to determine whether differences occurred between the club and lax NILs for each trait.