The effects of weather and nitrogen application rate on bread volume, protein concentration and gluten strength were investigated in spring and winter wheats in Sweden during 1990–96. The investigation was carried out in wheats containing the high-molecular-weight (HMW) glutenin subunit combinations 2+12 or 5+10.

The results showed that a warm (c. 20°C mean dry temperature) and dry grain-filling period, as during 1994 and 1995, led to high gluten strength. As a relatively gentle dough mixing is normally applied in Sweden when baking bread, excessively high gluten strength results in low bread volumes. Wheat cultivars containing HMW glutenin subunits 5+10 generally had higher gluten strength than those containing subunits 2+12. However, not all the cultivars containing subunits 5+10 showed overstrong gluten properties, whereas some cultivars containing subunits 2+12 were overstrong during 1994 and 1995. Different cultivars produced the highest gluten strength in different years. Generally, cultivars containing HMW subunits 2+12 gave higher bread volumes than those containing subunits 5+10. This is probably due to the Swedish baking method, where the dough is given a relatively gentle mixing for a fixed period of time.

Increased fertilizer rates led to increased protein concentration and decreased gluten strength. However, during certain years, for example 1994, the gluten strength was only decreased slightly by increased fertilizer rates, particularly in cultivars containing HMW glutenin subunits 5+10.