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一、前言为了选育速生、抗逆性强的榆树新品种,我们从1973年开始,通过属内种间人工有性杂交的方法,获得了遗传变异大,具有优势的杂种苗木。并通过3—6年的观察和对比试验,从中选出了三个优良株系,即白榆×多脉榆—20(编号75—02—20)、红果榆×白榆的二个系号(编号78—38—68、78—38—84)。与亲本、当地广为栽培的白榆比较,表现了杂交优势。生长快、干形通直、树形美观,对病、虫和土壤盐碱有一定的抗性。现将初步鉴定结果总结如下。
I. INTRODUCTION In order to breed new varieties of elm, which are fast-growing and resistant to stress, we have obtained hybrid seedlings with large genetic variation and superiority by means of artificial and sexual crosses among genus species since 1973. Through three to six years of observation and comparative experiments, three excellent lines were selected, namely, two elm lines of Ulmus pumila × Multi-vein Ulmus -20 (code 75-02-20), red elm × elm (Nos. 78-38-68, 78-38-84). Compared with the parents, widely cultivated elm in the area, they showed heterosis. Fast growth, stem straight, beautiful tree, the disease, insects and soil salinity have some resistance. Now the preliminary identification results are summarized below.