Abstract: Three wheat cultivars differing in grain protein content, Zhengmai 9023(strong-gluten wheat), Wenmai 4 (medium- gluten wheat)and Yumai 50 (weak-gluten wheat) were used in an experiment to study the dynamic changes of total sugar content and sucrose content in the flag leaf, stem, sheath and grain and the starch content in grain. Result showed that, the total soluble sugar and sucrose content in flag leaf in Wenmai 4 and Yumai 50 were higher than that in Zhengmai 9023, and the activities of sucrose(SS) and sucrose-phosphate (SPS) activity in flag leaf showed the same dynamic trend during filling stage.The time that the maximum of SS and SPS activity occurred was earlier than that of total soluble sugar content and sucrose content. Twelve days after anthesis the total soluble sugar content in grain of Yumai 50 was highest but that was lowest in Zhengmai 9023. During the filling stage the starch content in grain of Yumai 50 was highest among the three wheat cultivars, and the activity of adenosine diphosphorate glucose pyrophrylase (ADPP) showed the same trend during the later fiiling stage. The correlation analysis showed that there was a negative correlation between the total soluble sugar content in stem and the starch content in grain, and there was also a positive correlation between the total soluble sugar content in leaf, the sucrose content in leaf, total soluble sugar content in grain and the starch accumulating rate in grain after eighteen days after anthesis. The quantity and contribution to grain starch yield of remobilized total soluble sugar from top of 2nd and 3rd nodes of wheat stem in Yumai 50 and Zhengmai 9023 were the highest, but the quantity and contribution to grain starch yield of remobilized total soluble sugar from top of 4th and 5th nodes of wheat stem of Wenmai 4 were the highest.

Key words: Common wheat (Triticum aestivum Linn.), Leaf, Stem, Grain, Soluble sugars, Starch content