Experiment with different potassium levels in two winter wheat cultivars was carried from 1998 to 1999 The results showed that potassium could increase the photosynthetic rate after anthesis, the sucrose-phosphate synthase(SPS) activity and the accumulation of soluble protein content in flag leaf during the period of anthesis Potassium also increased the content of grain protein, wet gluten, and prolonged the dough development time and stability time, improved the grain quality and increased the grain y...