Effects of Interaction of Irrigation Times and Nitrogen Application Rates on Sucrose Content and Starch Accumulation in Both Flag Leaves and Grains of Weak-Gluten Wheat

To evaluate the effects of irrigation and nitrogen application and their interactions on starch accumulation and quality traits in grains of weak-gluten wheat, field experiment was carried out by using a weak-gluten wheat cultivar, Yumai 50, in the growth season 2003~2004. The results indicated that, as for cv. Yumai 50, nitrogen application rate of 150 kg/hm 2 enhanced both sucrose content in flag leaves and starch content in grains, and thus significantly increased grain yield. Whereas the treatments of high nitrogen application rate (270 kg/hm 2) and no nitrogen applied were not helpful to high yield and quality. Under this particular experimental conditions, twice irrigations (at Jointing stage plus grain filling stage) improved sucrose content in flag leaves and starch accumulation in grains, resulting in the highest grain yield. Whereas, either one (only at Jointing stage) or three-time irrigations (at Jointing stage, grain filling stage and maturity) decreased grain yield and quantity of weak-gluten wheat to some extent. Under the experiment, the nitrogen application of 150 kg/hm 2 and twice irrigations (at Jointing stage plus grain filling stage) were the ideal method for weak-gluten.