中文摘要：

为解决白桦育苗过程中的增施氮肥问题,以晚胺态氮（尿素）和硝态氮（硝酸钾）为氮源,通过9种不同氮素形态比例的施肥试验,确定了适宜白桦生长的氮素形态.增施化肥后,当年生白桦播种苗除根冠比（RSR）显著低于同一育苗基质的未施肥处理（CK）外,施肥处理下的苗高（丑）、地径（D）和生物量（S）均显著高于CK;增施不同形态的氮素虽然对D和S无显著影响（P〉0.05）,但显著影响H和RSR（P〈0.05）;随着总氮中酰胺态氮比例增加,H表现出增加趋势,而D、S和RSR均表现出抛物线式变化趋势;晚胺态氮有利于白桦幼苗的高生长和茎叶生长,而硝态氮有利于根系生长.由于容器苗起苗时不损伤根系,白桦容器育苗增施氮素时应首选酰胺态氮肥.

英文摘要：

In order to optimize nitrogen form of Betula platyphylla seedlings during nursery culture, experiments based upon the nine fertilization for different nitrogen form proportions was conducted by taking amide nitrogen （urea） and nitrate （potassium nitrate ） as the nitrogen source and the nitrogen form for appropriate growth of birch （ Betula platyphylla） was determined. The root - shoot ratio （RSR） of birch seedling with fertilization treatment were significantly lower than that of without fertilization treatment （CK）. the height （H） of the seedlings, root - collar diameter （D） , and biomass （B ） with fertilization treatments were significantly higher than those of without fertilization treatment. No significantly effects of nitrogen form on D and B （P 〉 0. 05 ） were observed. The effects of nitrogen form on H and RSR were significant （ P 〈 0. 05 ） . H increased with the amide nitrogen proportion increasing. D, B ,and RSR presented parabolic changing trend. The amide nitrogen were good for growth stem and leaives of birch seedlings. Nitrate nitrogen was better for growth of root. Because of the advantage of no - hurt to root by container seedling, the optimal nitrogen form was amide ni-trogen for nursery culture of container seedling.