Environmental modification of hard red winter wheat flour protein composition

The intrinsic processing quality of wheat (Triticum aestivum L.) cultivars is modified significantly by cultural conditions and climate. In an attempt to understand the biochemical basis of such variation, environmental modification of flour protein content and composition was measured. Thirty hard red winter wheat cultivars and experimental lines were grown at 17 Nebraska environments during 1990 and 1991. Environmental conditions, including grain filling duration, temperature and relative humidity during grain filling, were monitored. Grain yield and test weight also were determined as environmental indicators. Significant linear correlations between flour protein content, as measured by near-infrared spectroscopy, were observed only with the duration of grain filling. Protein quality, as measured by SDS sedimentation volumes and size-exclusion high-performance liquid chromatography, was highly influenced by the frequency of high temperatures during grain filling and by the relative humidity. Observed ranges in genotypic responses (variance) at locations also were altered by environmental factors. Optimal protein quality, as determined by SDS sedimentation volumes, was observed with exposure to less than 90 h of temperature greater than 32°C during grain filling. Protein quality declined with exposure to a greater number of hours of elevated temperature.