UNIVERSITY OF AGRICULTURAL SCIENCES, VIENNA
Department of Plant Breeding, Gregor Mendel Str. 33, A-1180 Vienna, Austria.
Selection for bread-making quality using microscale tests.
Heinrich Grausgruber, Adelheid E. Kreuzmayr, and Peter Ruckenbauer.
Breeding for wheats with a high performance in bread-making quality has a long tradition in Austria. The acreage of quality wheats is more than two-thirds of the acreage of wheat seed multiplication. Selection for bread-making quality traditionally is based on the Zeleny sedimentation volume, the protein content, and the grain hardiness. We investigated several tests on a micro-scale in regard to their effectiveness to separate quality, bread, and feed wheats.
A set of 34 wheat cultivars covering the whole range of quality groups according to the Austrian quality classification scheme of 1994 was investigated for protein content, wet gluten content, sedimentation volume, HMW-glutenin subunit composition, dough characteristics, and loaf volume. The dough characteristics (stickiness, extensibility, resistance, and energy) were determined with a Texture Analyzer TA.XT2 (Stable Micro Systems Ltd.) on 20 g of dough. The volume of small bread loaves made from 50 g of dough was determined with a Panasonic home bakery. This home bakery was used only for fermentation and baking. Kneading of the dough was carried out by a mixer, because the kneading of the home bakery is too weak compared with Austrian baking procedures.
The dataset of 11 quality parameters per cultivar was subjected to a discriminant analysis. The analysis revealed a highly significant first canonical discriminant function. Dough characteristics and the loaf volume showed the greatest contributions to discrimination. Cultivars of foreign origin that are potential crossing partners for agronomic characters also were evaluated by the microtests, and their data along with the data of the Austrian cultivars were subjected to a principal component analysis. The joint relationships between wheat cultivars and quality traits were depicted by a biplot. In that way, the quality characteristics of the potential crossing partners were made comparable to the Austrian classification scheme. Both statistical analyses revealed that the microtests allow a reliable assessment of the bread-making quality of Austrian wheats.
Because the microtests are more laborious than a simple measurement of the protein content by NIRS, they cannot be recommended as selection tools in early generations when thousands of breeding lines must be evaluated. However, the microtests are particularly valuable for the evaluation of quality of advanced breeding lines and/or genotypes of unknown quality characteristics, which are intended to be used as crossing partners in the breeding program. Thus, crosses between two genotypes with the same negative dough and/or baking characteristics can be avoided, which is often not the case if only indirect quality traits (protein content, sedimentation volume, HMW-glutenin score) are used.