F₃ response to F₂ selection for quality and its effect on F₃ yield distribution

Abstract

Seed of F2 single plant selections from two crosses was evaluated using a number of small-scale quality tests.F2 quality test values were significantly correlated with farinograph and extensograph properties in the F3, but no one test was correlated with all of the physical dough measures. The Pelshenke time and the proportion of residue protein were the small-scale measures most consistently correlated with dough strength (farinograph dough breakdown and extensograph maximum resistance) in the F3 and between the F2 and F3 generations.Applications of independent culling in the F2 for each test did not alter the subsequent nature of the F3 yield distribution except for flour protein content and Zeleny volume, where there was a preferential loss of lines from the higher yielding end. This resulted from the negative correlations between flour protein content and yield, both within the F3 (r=-0.66**) and between the F2 and F3 (r= -0-44**). The negative relationship between grain yield and Zeleny volume was due to the effect of protein content on Zeleny volume.Application of quality testing regimes that estimated grain hardness, protein content and dough strength in the F2 did not adversely affect the nature of the F3 yield distribution, yet permitted up to 71% of the population to be removed because of unsatisfactory balance of quality attributes. These results have considerable implications for the planning of wheat breeding programmes.Additional keywords: Bread wheat (Triticum aestivum L.), sodium dodecyl sulfate sedimentation volume, Zeleny sedimentation volume, Pelshenke wheatmeal fermentation time, residue protein content.