ABSTRACT
Extreme temperatures during grain filling have been identified as a major source of variation in wheat quality characteristics. In this study one biscuit, two bread, and one durum wheat cultivars were evaluated in two consecutive seasons for reaction to extreme high and low temperatures during grain filling. In both years, the soft biscuit wheat cultivar showed the largest reaction to low temperature stress, where the monomeric proteins were significantly increased and the polymeric proteins significantly decreased. The effect of temperature stress was more pronounced in the second year, with an earlier planting date. The durum wheat reacted to both heat and cold stress in the second year, where the small polymeric proteins were significantly reduced, and the small and large monomeric proteins were increased with stress. The effect of wheat type was much more pronounced than the effect of temperature treatments on the protein fractions. The protein fractions of the tetraploid durum wheat were very different from the hexaploid cultivars, with much less polymeric proteins, and more monomeric proteins. The soft biscuit wheat had significantly less large polymeric proteins and more large monomeric proteins than the bread wheat cultivars for both years.
