QUALITY OF HARD RED WINTER-WHEAT GROWN UNDER HIGH-TEMPERATURE CONDITIONS DURING MATURATION AND RIPENING

High temperature during grain filling has been identified as a major f actor in the end-use properties of bread wheat (Triticum aestivum L.). Our objectives were to assess the effect of high temperature during m aturation on the grain characteristics, milling quality, and flour qua lity of hard red winter wheat. In three separate experiments, plants o f wheat cultivar Karl 92 were subjected to regimes (day-night) of 20-2 0, 25-20, 30-20, and 35-20 degrees C from 10 and 15 days after anthesi s (DAA) until ripeness, and 25-20, 30-20, and 35-20 degrees C from 20 DAA until ripeness. In other experiments, plants of wheat cultivars Ka rl 92 and TAM 107 were dried at 20 and 40 degrees C, and spikes of Kar l 92 were dried at different temperature and humidity conditions to as ses the effects on quality of high temperature and drying rates during grain ripening. Flour yield correlated positively with kernel weight and diameter, test weight, and proportion of large kernels. Flour yiel d decreased as temperature increased and correlated negatively with ha rdness index and proportion of small grains. High growth temperatures and rapid grain desiccation decreased mixing time and tolerance of the flours. The greatest damage occurred when high temperature was mainta ined continuously from early grain filling until ripeness. Weakening o f dough properties by rapid desiccation during ripening suggest that t emperature, humidity, and possibly soil moisture all contribute to the final quality of bread wheat.