The close study on the four selected clones that grow fast (No. 47), intermediately (No. 64 and No. 48) and slowly (No. 51) shows they have same growth pattern, but the amount is different.

• 代表生长速度快（47号杨）、中等（64号杨和48号杨）、慢（51号杨）的4个无性系生长规律是相似的，只是数量有所差别。 生长速度快的无性系数量成熟期晚于生长较慢的无性系。