Effects of all straw returned to the field on grain number and grain weight at different spikelets and grain positions in winter wheat.

【Objective】 The objectives of this study were to research the change of gain number and grain weight of wheat with spikelet and grain position in main stem and tiller spike under the condition of straw returned to the field.【Method】 A location field experiment was conducted from 2008 to 2010,single maize straw returned to the field,single wheat straw returned to the field,wheat and maize straw returned to the field were conducted to study the effects of straw returned to the field on grain number and grain weight at different spikelets and grain positions in winter wheat.【Result】Results showed that,the spike per hectare,grain number per spike,1 000-grain weight and yield were increased in treatment of straw returned to the field.The distribution of grain number,spikelet weight,and grain weight with the spikelets positions showed parabolic changes,so as the grain weight at 1st,2nd,3rd in each treatment and 4th in treatment of straw returned to the field.The more fertile spikelet number and less difference in spikelet grain number and single grain weight,the smoother the parabola was.The fertile spikelet number and spikelet grain number in main stem and tiller spike were increased in treatment of straw returned to the field,the increase range of fertile spikelet number in the bottom spikelet were bigger.There were different increasing effects of straw returned to the field on single grain weight at different grain positions,especially for at of 3rd and 4th grain position.【Conclusion】 Therefore,under the condition of wheat and maize straw returned to the field,grain yield and yield components,spikelet grain number and grain weight at different spikelets of wheat were enbanced.