白榆,深受广大群众的喜爱,已成为我县仅次于杨树的阔叶速生树种。七十年代以来,我县连年从山东省鄄城县调进大量白榆种子。在山东白榆种子成熟期为5月1日前后,调回我县的时间是5月中下旬,而5—6月正值旱季,种白榆的地方又多在丘陵区,采用旱地育苗,往往由于土壤墒情不好而延迟至7—8月播种,这样当年的生长期仅60～80天,影响苗木生长量。若将种子放至翌年播种,又因种子寿命短,极易丧失发芽 White elm, deeply loved by the masses, has become the county after poplar broadleaf fast growing tree species. Seventies, my county year after year from Juancheng County, Shandong Province transferred a large number of elm seeds. Shandong elm seed maturity before and after May 1, transferred back to my county in late May, and May-June is the dry season, the species elm in the hilly areas, the use of dry land nursery, Often due to poor soil moisture and delayed planting until July-August, so the growing season was only 60 to 80 days, affecting seedling growth. If the seeds were put into the following year sowing, because of the short seed life, easily lost germination