Analysis on Yield Composition Factors of Rice High Yield Population in Cold Region

The survey on 60 quality groups that different fertilizer and density factors constitute.The results showed that the investigation and analysis on 60 different groups of spike number,grains per panicle,seed setting rate,grain weight,spike number of high yield population concentrated in the 4 500~ 4 950 thousand per hectare,the grain number per spike of high yield population should control in the range of 90 to 130 in cold region;within this range,the effect of chang of grain number per spike on yield was not significant.The role of different yield compositon factors on different yield level rice population was different;the role of each yield compositon factors in high yield population was:seed setting rategrain number per spikespike numbergrain weight;in middle yield population was:spike numbegrain number per spik seed setting rategrain weight;in low yield population was:spike number seed setting rate grain number per spike grain weight.