A SURVEY OF THE EFFECTS OF HIGH-TEMPERATURE DURING GRAIN FILLING ON YIELD AND QUALITY OF 75 WHEAT CULTIVARS

The responses of 75 cultivars of wheat to a short (3 day) period of very high temperature (40 degrees C max.) applied at either 10 or 30 days after anthesis were examined under controlled conditions. The effect of high temperature on a number of yield (grain number, individual kernel mass and N per kernel) and quality components (protein composition, apparent amylose content and noodle swelling power) is described for the sample population and for a number of varieties which were either particularly heat tolerant or sensitive. Genotypic variation of response to high temperature of the order of 20% was recorded for the majority of yield and quality components. The fact that responses of this magnitude were caused by exposure to high temperatures lasting only 5 to 6% of the grain filling period demonstrates the extent to which short periods of very high temperature may affect wheat yield and quality.