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钻天榆(又叫立枝榆)是白榆的优良自然类型.它冠形美、干形直,枝干角不超过45度.在河南7—10年生胸径可达20—25厘米,树高18—20米.比一般白榆高生长快1.5—2倍,材积生长快2—3倍.材质坚韧有弹性,深受群众欢迎.一、实生苗引种1975年我场由兄弟单位引来河南钻天榆1年生实生苗100余株,植株行距1×5米.78年秋测80株5年生实生苗高5.81—7.8米,胸径5.8—8.4厘米.平均每年高生长1.16—1.56米,胸径生长1.16—1.68厘米.高生长超当地6年生白榆实生苗30.8%,胸径超33.9%.
Dried sky elm (also known as standing elm) is an excellent natural type of elm .Its crown-shaped, dry straight, branch angle does not exceed 45 degrees in Henan 7-10 years old breast diameter up to 20-25 cm, the tree High 18-20 meters. Grow faster than the general Elm 1.5-2 times faster, volume growth 2-3 times faster. Tough and flexible material, welcomed by the masses. First, the introduction of seedlings in 1975 my field led by the fraternal unit Henan drilling days elm 1-year-old seedlings more than 100 strains of plant spacing 1 × 5 meters .78 autumn measured 80 5-year-old seedlings 5.81-7.8 m in height, diameter 5.8-8.4 cm. Average annual high growth of 1.16-1.56 meters, diameter Growth 1.16-1.68 cm. High growth over the local 6-year-old white elm seedlings 30.8%, breast diameter exceeding 33.9%.