【摘要】 以光皮桦苗高月净生长量为样本 ,采用有序样本聚类分析将光皮桦苗高生长过程划分为 4个时期 ,出苗期为 5月 1 0日～ 5月 31日 ,幼苗期为 6月 1日～ 7月 31日 ,苗高速生期为 8月 1日～9月 30日 ,苗木生长后期为 1 0月 1日～ 1 2月 31日 .苗高速生期时间推迟到 8～ 9月 ,原因是由于当年 5月上旬播种 ,播种时间推迟 ,速生期苗高生长量占苗木全年总生长量的 5 1 .87% .提出了各期的关键育苗措施 .保证苗高速生期有充足的水肥条件 ,延长苗高速生期提高生长量更多还原

【Abstract】 The height growth process of Betula luminifera seedlings is divided into four stages with the sequential sample cluster analysis,taking the height net growth increment of Betula luminifera Seedlings as samples:emergence stage(May10 ~31),early growth stage(Jun 1~Jul 31), rapid growth stage(Aug 1~Sep 30)and late growth stage(Oct 1~Dec 31) The rapid growth stage is later because of sowing time being later,but it’s growth increment accounts for 51 87% of the total growth increment It is very important for the growth increment enhancement to guarantee enough water and fertilizers at the rapid growth stage and lengthen its time The managements for each stage were given out更多还原