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白榆(Ulmus Pumila L.)是我省平原四旁重要的乡土用材树种,有悠久的栽培历史。据1976年“四.五”林业资源清查,全省有白榆3.7亿株,占四旁树种的18.7％。目前白榆生产上存在的突出问题是,干形低矮扭曲,生长缓慢(1982年对孟县20片树龄18——20年生,株行距为2×2m的白榆小片林调查,胸径年平均生长量为0.98cm,干型通直的为16.18％),亟待进行遗传改良。但考虑到白榆的繁殖生物学(异花授粉,自然下种成苗)形成的杂合基
Ulmus Pumila L. is an important indigenous timber species on four sides of the plain of our province and has a long history of cultivation. According to the “April 5” inventory of forestry resources in 1976, there were 370 million elm white elm in the province, accounting for 18.7% of the trees on the four sides. At present, the outstanding problems existing in the production of Ulmus pumila are dry low distortion and slow growth. (In 1982, 20 20-year-old trees of Mengniu, with an interval of 2 × 2m, Growth of 0.98cm, dry through straight to 16.18%), urgent need for genetic improvement. However, taking into account the reproductive biology of Ulmus (cross-pollination, under the natural seedlings) formed by the heterozygous