[Effect of potassium application stage on photosynthetic characteristics of winter wheat flag leaves and on starch accumulation in wheat grains].

In this study, the same amount of potassium was applied as basal dressing (treatment 1) and as basal dressing and top-dressing at jointing stage (treatment 2). The results showed that treatment 2 improved the photosynthetic rate and sucrose-phosphate synthase (SPS) activity of winter wheat flag leaves and the adenosine diphosphate glucose pyrophosphortlase (ADPGPPase) activity in wheat grains. It increased the supplying strength of sucrose and the accumulation rate of starch in the grain, and also, the grain yield. Both of the treatments improved the synthesis capacity of sucrose in wheat flag leaf and the transformation capacity from sucrose to starch in wheat grain, die to the coordinative relationship between source and sink of starch synthesis, including the synthesis, transport and transformation of photosynthate.