氮素营养对尾巨桉幼苗生长和质量的影响

对尾巨桉DH32-29容器苗苗期进行5个水平的指数施氮肥处理,研究不同施氮量的指数施肥方法对苗木的生长、SPAD值和苗木质量指数的影响。结果表明:经过施肥处理的苗木其苗高、地径、生物量、SPAD值和苗木质量指数分别为不施肥处理的260.7%、228.7%、654.8%、129.9%、571.2%;尾巨桉幼苗的苗高、地径、生物量、SPAD值和苗木质量指数随着施氮量的增加呈先增大后减小的趋势。施氮量为50mg·株-1的苗木苗高最大,施氮量为100mg·株-1的地径、生物量和苗木质量指数均为最大,SPAD值在施氮量为150mg·株-1时达到最大;不施肥处理的根冠比最大,苗高、地径、生物量、SPAD值和苗木质量指数均最小;施氮量为100mg·株-1的苗木质量最好,为最佳指数施氮量。

Effects of Exponential Nitrogen Nutrition on Growth and Quality of Eucalyptus Seedlings

An exponential fertilization trail was conducted with five levels（0,50,100,150,200 mg·seedling-1） of nitrogen fertilizer to assess the effects of different levels on growth,leaf chlorophyll content and quality index of Eucalyptus urophylla×E.grandis clone DH32-29 nursery plants.The results showed that the mean height,ground diameter,biomass,chlorophyll content and quality index of these nitrogen fertilizer levels were 260.7%,128.7%,554.8%,129.9%,471.2% more than those with no fertilizer respectively.Height,ground diameter,biomass,chlorophyll content and quality index of E.urophylla×E.grandis plants increased at first with the increase of nitrogen supply,but then decreased markedly.The tallest plants were obtained with 50 mg·seedling-1 of nitrogen and the maximum chlorophyll content with 150 mg·seedling-1 of nitrogen.When the nitrogen level reached 100 mg·seedling-1,the ground diameter,biomass and quality index were maximum.The treatment with no fertilizer had the biggest root-shoot ratio,but other indexes were all at their minimum values.It was concluded that 100 mg·seedling-1 nitrogen would be the optimal level for production of quality nursery plants of the clone E.urophylla×E.grandis DH32-29.