Wheat quality parameters in a heat-damaged paddy environment in China. A two-year field experiment was conducted to study the effects of heat stress on the quality of grain at harvest. The results indicate that the moisture and chlorophyll (CHL) contents, damaged starch content (DSC), alkali spreading value (ASV), wet gluten content (WGC), wet gluten index (WGI), and relative maturity (RM) in the grain significantly increased, while protein content (PC) and moisture absorption rate (MAR) in the grain were reduced under heat stress. During the study period, heat stress delayed grain filling; consequently, the average daily CHL content of grain at 25 degrees C was significantly reduced and RM increased. When the average daily temperatures exceeded 31 degrees C, there was no significant difference in ASV and WGI for all treatments and the mean values were much lower than the standard values. Furthermore, the decrease in ASV and WGI was associated with a reduction in kernel weight. It is concluded that heat stress reduced the quality of wheat grain at harvest and the standard grain qualities recommended in China were not suitable for the heat-damaged paddy environment of China. The data suggested that under normal moisture conditions, grain quality could be reduced by heat stress at the filling stage.