SOME EFFECTS OF TEMPERATURE REGIME DURING GRAIN FILLING ON WHEAT QUALITY

The effects on wheat quality of temperature during grain development have been studied using both field- and glasshouse-grown samples. Correlations were sought between quality of doughs from the Interstate Wheat Variety Trials and average daily maximum and minimum temperatures for the period from anthesis to harvest. (The data were for several sites over six seasons). In pot trials, differential temperature regimes were imposed at different stages during grain development to assess the effects on quality. Air temperature during grain development markedly influenced properties associated with baking quality, particularly dough strength, also loaf score and volume. Increases in daily average temperature up to about 30°C increased dough strength. Temperatures above this threshold value, even applied for periods of only three days, tended to decrease dough strength. These effects occurred apparently independently of effects of temperature on kernel weight or protein concentration as they were observed in cases where high temperature treatments were delayed until late in development after maximum dry weight had been reached. At the practical level, the work points to the need to take into account the effects of temperature during grain development when considering the functional properties of gluten in a particular sample. It suggests that an index could be constructed to identify cropping regions where grain quality may have been modified by high temperature during the growing season. © 1990 CSIRO. All rights reserved.