我国榆属树种约有25种,其中以白榆分布最广,栽培利用最多,是华北平原四旁绿化和小片林的主要树种,但生长较慢,侧枝粗大,主干低矮,迫切需要选育生长快、干形好的良种。榆属各种,长期适应不同地理区域的土壤气候条件的结果,形成了各不相同的生物学特性,具有不同的经济价值,这就给杂交育种工作提供了丰富的原始材料。 我们从1972年进行榆属种间杂交育种,十年来先后利用十几个种进行了近30个杂交组合的试验,后期还利用杂种做亲本进行了复交,先后获得杂种苗5000余株,选 There are about 25 species of Ulmus species in our country, of which Ulmus excels widely and has the most cultivation and utilization. It is the main tree species of greening and small patches around the North China Plain. However, it grows slowly with thick side branches and low trunk, which urgently needs breeding Fast, dry good seed. Ulmus species, long-term adaptation to different geographical regions of the soil and climatic conditions result in the formation of different biological characteristics, with different economic value, which gives hybrid breeding work provides a rich source of raw materials. We carried out hybrid breeding between Elm species in 1972. Over the past ten years, we have used more than a dozen species to conduct experiments on nearly 30 hybrid combinations. In the later period, we also used hybrids as the parents to restore hybridization. More than 5,000 hybrid seedlings were obtained successively