不同施氮处理对乌桕容器苗养分状况的影响

研究不同施N处理对乌桕容器苗营养元素和非结构性碳水化合物的影响,筛选出培育乌桕容器苗的最佳施肥方法和施氮量。以当年生乌桕容器苗为试验材料,设置传统施肥(C600)、指数施肥(Z200、Z400、Z600、Z800、Z1000)和不施肥(CK)共7个处理,分别测定不同N素施肥处理对乌桕容器苗N、P、K等营养元素浓度(质量分数,下同)、积累量和可溶性糖等非结构性碳水化合物含量的影响。结果表明,各施N处理对乌桕容器苗养分状况均有显著影响。随施N量的增加,乌桕容器苗各器官的N浓度都是先增后减,最大值出现在指数施肥Z600处,根、茎、叶的N浓度分别为101.80、91.50 mg·g^-1和121.33 mg·g^-1。乌桕容器苗各器官P浓度都较对照有所降低。指数施肥条件下,根和茎中的K浓度随施N量的增加逐渐降低,叶中的K浓度随施N量增加呈现先增后减趋势,在Z600处达到最大;乌桕容器苗地上部分、地下部分和全株的营养元素积累量都随施N量的增加出现先增后减趋势,最大值都出现在Z600处;在指数施肥的各处理中,乌桕容器苗根、茎、叶各器官中的可溶性糖含量随施N量...

Effects of Different Nitrogen Application Treatments on Nutrient Status of Sapium sebiferum Container Seedlings

The study aimed at determining the effects of different nitrogen applications on the nutrient elements and non-structure carbohydrate accumulation of Sapium sebiferum container seedlings,further exploring the most proper method of nitrogen application.The current year S.sebiferum container seedlings were used as experimental materials.Seven nitrogen-application treatments including traditional fertilization (C600),exponential fertilization (Z200,Z400,Z600,Z800,Z1000) and no fertilization (control) were set up.The parameters including the concentration and accumulation of nutrient elements (nitrogen,phosphorus and potassium) and the non-structural carbohydrate content (soluble sugar and starch) in different organs were measured.All nitrogen application treatments significantly affected the nutrient status of S.sebiferum container seedlings.With the increase of nitrogen application,the nitrogen concentration in all organs first increased and then decreased,and the maximum values appeared at the exponential fertilization of Z600.The nitrogen concentrations in roots,stems and leaves were 101.80,91.50,and 121.33 mg·g^-1,respectively.Nonetheless,the phosphorus concentrations in all organs were lower than that of the control.Under the condition of exponential fertilization,the potassium concentrations in roots and stems decreased gradually with the increase of nitrogen application,while the potassium concentration in the leaves had the uptrend first and the downtrend latter with the peak value in treatment Z600.The nutrient element accumulations of aboveground part,underground part and whole plant also appeared the highest values in Z600.As the nitrogen application amount increased,the soluble sugar content in roots,stems and leaves went up first and declined subsequently under exponential fertilization,reaching the maximum value in Z600,which were 63.73,55.55 and 134.70 mg·g^-1,respectively.The promoting effect of exponential fertilization on the soluble sugar accumulation was more effective than that of traditional fertilization.Except for C600 and Z200,the starch contents in roots of other fertilization treatments decreased compared with the control,and the root starch content was negatively related to the nitrogen application under the exponential fertilization.In stems and leaves,there was no significant difference in starch content between each fertilization treatment and the control.Exponential fertilization was superior to traditional one.The nutrient element concentration,amount of element accumulation and non-structural carbohydrate content were the highest in the treatment Z600,which was proved to be the optimal treatment for S.sebiferum container seedlings.