Cultivar and environmental effects on quality characters in wheat. II. Protein

Glutenins and gliadins are the major components of the storage protein in wheat and make a significant contribution to dough rheology and baking quality. Qualitative differences in these proteins are known to be important for dough rheology, particularly for glutenins, but much less is known about quantitative differences, especially as influenced by field environment. Flour protein, the proportion of glutenin and gliadin in flour protein, loaf volume, and the dough rheological characters dough development time, dough breakdown, dough extensibility, and maximum dough resistance (Rmax) were determined for 7 cultivars grown in 15 diverse environments. The proportion of glutenin in flour protein was highly dependent on cultivar, whereas, although cultivar was still important, environmental variation was greater than cultivar variation for gliadin. Environmental variation was greater than cultivar variation for the dough rheological characters. Across environments, the proportion of gliadin increased with increasing flour protein, whereas the proportion of glutenin decreased. An index of accumulated temperatures above 30 degrees C during the first 14 days after anthesis explained a significant proportion of the increase in gliadin, and, to a lesser extent, the decrease in glutenin. Increasing Rmax and dough development time, and more rapid dough breakdown, were also associated with this index. The rate of increase of Rmax with the temperature index was greater for cultivars with the Glu-D1a allele than those with the Glu-D1d allele, suggesting that the relative performance of cultivars with different alleles at this locus depends on environment.