毛白杨1971年引进延安市,生长情况良好。5年生毛白杨平均高9.8米,平均胸径11.6厘米,是四旁绿化、城市绿化的优良树种之一。枣园苗圃1972年开始毛白杨育苗试验,曾用接炮捻、芽接、埋株、埋条等方法进行试验,但都不够理想。在上级党委的直接领导下,由于部、工人、技术人员组成三结合的科学实验小组,以毛主席的哲学思想为指导,大胆试验,反复实践,经过几年的努力,结合 Populus 1971 introduced Yan’an City, good growth. 5-year-old Populus average 9.8 meters high, average diameter 11.6 cm, is surrounded by green, one of the fine tree species of urban greening. Zaoyuan Nursery Poplar seedling experiment started in 1972, had used gun twisting, budding, buried strains, buried strips and other methods of testing, but not ideal. Directly under the direct leadership of the party committees at the higher levels, the scientific experiment team composed of three ministries, workers and technicians, under the guidance of Chairman Mao’s philosophical thinking, boldly tests and practices repeatedly. After years of hard work,