Abstract: A total of 7 height gradient series were tested including 35 systems and 5 parental varieties, Canonical analysis and stepwise regression were used in the study on relations between the height constituent factors and the yield/yield biology factors, Results indicated:1 .The height factor affected the yield factor through yield biology, and high yield was based on a certain amount of biological yield.2 .The hightening of the short variety benefited the yield increase,the 1000-kernel weight and the harvest index without any significant effects on the protein content, The shortening of the tall variety could significantly increase the harvest index with little influence on the protein content of the kernel.3.When the main characters met the breeding goal, the selection of such types that had longer last-but-one internodes, longer distance between the first and the second leaves, and longer ear collar and longer ears, could help increase the yield.

Key words: Stem height, Gradient series, Wheat, Multiple analysis