Abstract:

Canopy temperature during the grain filling stage can affect grain yield and quality. Previous studies have focused on the effects of canopy temperature on physiological characteristics and yield, and its measurements have been used widely in recent years to study genotypic responses to drought and heat stress. This paper aims to understand the effects of canopy temperature on the main quality traits of winter wheat (Triticum aestivum) cultivars. The dynamic changes in the accumulation of protein and starch components during the filling stage in the grain of winter wheat cultivars with different canopy temperature characteristics were studied in Henan Province over two growing seasons (2001 _ 2003). The results indicated that the canopy temperature of the three cultivars changed a lot during the filling stage. During the early stage, average canopy temperatures were maintained but there was a strong change in temperature among the cultivars during the mid and late filling stage, especially in the late filling stage. In the mid and late stage, the canopy temperature of ‘Yumai 50’ decreased and expressed a cold tail type. The canopy temperature of ‘Yumai 34’ and ‘Yumai 70’ tended to rise at the mid and late stages and expressed a warm tail type. The difference in canopy temperatures between the cold and warm tail type cultivars could be greater than 2 ℃. There were differences in patterns of protein and starch accumulation in the grain among cultivars. Accumulation of albumin, globulin and glutenin were significantly different in the late grain filling stage between warm and cold tail type cultivars, but there were no differences in gliadin accumulation. No significant differences of glutenin accumulation was observed within 15 d post_anthesis, but by 20 d after anthesis, significant differences (1% level) were observed between the two cultivars with different canopy temperature characteristics during the grain filling stage. Accumulation content of glutenin of ‘Yumai 34’ and ‘Yumai 70’ at harvest were 46.19% and 19.7% higher than ‘Yumai 50’, respectively. The ratio of glutenin to total protein showed the same trend and indicated that the rising canopy temperature during the filling stage resulted in higher accumulations of glutenin. The content of glutenin was positively and significantly correlated with canopy temperature in the mid, late and total grain filling stage. The content of starch and amylose/amylopection during the grain filling stage did not show significant differences between the two types of cultivars, but significant differences (1% level) were found in pasting parameters, such as the peak of viscosity, through viscosity, final viscosity, pasting time, pasting temperature and setback value with the exception of the breakdown value. In particular, through viscosity of ‘Yumai 34’ and ‘Yumai 70’ were both 84.4% higher than that of ‘Yumai 50’, and final viscosity was 60.9%, 58.2% higher than that of ‘Yumai 50’, respectively.

Key words: Winter wheat, Canopy temperature character, Protein components, Starch components, Accumulation