Comparison of small-scale and large-scale extensibility of dough produced from wheat flour
Extensibility and dough strength are key traits for varietal selection in most wheat-breeding programs. As there are several techniques for measuring these traits there is interest in examining the agreement between methods in terms of genotypic (varietal) rankings. We investigated this issue using 2 different extension methods; namely, small-scale (modified Kieffer) and large-scale (Brabender Extensograph) methods. Data were obtained from a doubled-haploid population (190 lines) from a Chara (high extensibility, excellent dough strength) × WW2449 (low extensibility, poor dough strength) cross that was grown in a field trial at the Wagga Wagga Agricultural Institute (WWAI) in 2000. Six extensional rheological traits were measured and compared according to a multivariate mixed statistical model. The estimated genetic correlation matrix for 4 of the 6 extensibility traits (R_Max, area, height, and resistance at 5 cm extension) revealed that for these dough strength related parameters, both methods were measuring equivalent traits. Comparisons of the extensibility traits length and extensibility at Rmax demonstrated that, although substantial amounts of the variance are controlled by the same glutenin loci, the traits differed in the allocation of variance across the loci, and the sources and magnitude of non-genetic variance. The data verified that small-scale testing is a robust and efficient alternative to large-scale testing for both commercial breeding and research.