Abstract: Nine wheat cultivars with different protein contents, GMP content, wet gluten content, SDS sedimentation, and dough stability time at maturity were classified into three groups: high GMP content and high dough stability time, low GMP content and low dough stability time, and medium GMP content and medium dough stability time. The dynamic changes in the content of soluble protein and the activity of the enzymes in relation to protein synthesis and degradation and their relationships to characteristics of processing quality were studied during grain filling. The results showed that protein content was not related to wet GMP content, SDS sedimentation, and dough stability time but GMP content was significantly related to the said indices, implying that GMP content was more representative to processing quality than protein content. During the early period of grain filling NR and GS activities had significants effect on soluble protein content and during the later period EP, CP and AP activities has significant effects. The group with high GMP content had higher soluble protein content than other groups. The above results indicated that during grain filling, higher soluble protein level, namely high NR and GS activities during the prophase and metaphase, and high EP, CP, and AP activities during the metaphase and anaphase, was the physiological basis for high GMP content.

Key words: Wheat, Cultivars, Quality, Relative enzymes