Gluten index compared with SDS-sedimentation volume for early generation selection for gluten strength in durum wheat

Gluten strength is an important end-use quality factor in durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.], affecting pasta manufacture and cooking quality. The objective of this research was to determine the inheritance and heritability of gluten index in comparison with the widely used SDS-sedimentation (sodium dodecyl sulphate) technique for selection for gluten strength. Seven durum populations were grown in replicated, multi-location, multi-year field trials in Saskatchewan, Canada, during the period 1995 to 2002. Gluten index and SDS-sedimentation volume were determined on all plots after harvest. Both traits were affected by genotype, and to a lesser extent by year or location. Genotype environmental interactions were generally minor. The majority of genotypes in each population had similar relative ranking for gluten index and SDS-sedimentation volume in each environment. Both traits were highly heritable, ranging from 0.80 to 0.97, and both were complexly inherited with estimates of effective factors ranging from 3 to 21. Gluten index and SDS-sedimentation volume were highly correlated, indicating that they are measuring similar aspects of gluten strength. SDS-sedimentation volume was positively associated with protein concentration (r2=0.52), but gluten index was not. Therefore, gluten index would be more desirable than SDS-sedimentation volume for use in selection where there are within-trial protein concentration trends.