毛白杨留根繁殖是河北省林研所试验场创造的育苗技术,它的优点很多:可以节约种条,节省劳力,技术容易掌握,苗木质量较好。但目前存在的问题是:苗木地面分布不够均匀,常出现缺苗断垄的现象,直接影响着产量。为此,我们从1976年开始,研究利用留根圃地上丛生过密的幼苗来提高毛白杨留根繁殖的产量。即在当年初夏,就地分株,拉倒压条,简称幼苗拉牛或嫩条拉牛。培育出的新苗, Populus tomentosa root propagation is the Institute of Forestry, Hebei Province, the test site to create seedling technology, which has many advantages: you can save seeds, save labor, easy to grasp technology, seedling quality is better. However, the existing problems are: the uneven distribution of seedlings on the ground, often lack of seedlings off the ridge, a direct impact on production. To this end, we started in 1976 to study the use of root nursery over-dense seedlings to increase poplar poplar reproduction. That early summer of the year, ramets on the spot, pull down the pressure strip, referred to as seedling pull cattle or tender pull cattle. Nurturing the new seedlings,