当前,我国在营造杨树人工林中,突出存在的问题是品种单一化,无论是黄淮海平原,还是长江流域,大片的杨树几乎使用的是同一无性系,据统计,我省现栽培的杨树林1—69扬占90%以上。虽然,在一定时期和范围内,也能培育出速生高产的林分,但在大面积推广中存在着潜在的危险,由于单系品种的遗传基础越演越窄,往往会造成品种退化或某种自然灾害。如病虫危害猖獗等而全功尽弃,田内、外都有过许多惨痛的教训。林上育种专家提出了“多系品种”的理论。如西欧等国杨树造林采取多品系混合造林基础上,实际按比例多品系的组配。西德提出:杨树由5—20个无性系按比例组成一个多系品种。省林科所杨树育种课 At present, in our country to create a poplar plantation, the prominent problem is the variety of a single, whether it is the Huang-Huai-Hai Plain, or the Yangtze River valley, poplar almost use the same clones, according to statistics, our province is now cultivated Poplar 1-69 Young accounted for more than 90%. Although, in a certain period and range, fast-growing and high-yield stands can also be cultivated, there is a potential danger in large-scale popularization. As the genetic basis of single-line breeds becomes narrower and narrower, they often cause varieties to deteriorate or some Natural disaster. If pests and diseases are rampant, etc., they are completely abandoned. There have been many painful lessons both inside and outside Tian Field. Lin breeders experts put forward the “multi-line varieties ” theory. Such as Western Europe and other countries poplar afforestation to take multi-line mixed afforestation based on the actual proportion of multi-line combination. West Germany proposed: Poplar consists of 5-20 clones in proportion to form a multi-line species. Forestry Branch poplar breeding class