【目的】采用15N、13C同位素示踪技术,通过对不同施氮量下嘎啦幼苗生长状况及氮、碳分配、利用特性等的研究,以期为苹果生产合理施肥提供依据。【方法】将2年生盆栽嘎啦幼苗进行低、中、高三个氮水平处理,同时进行15N标记。在新梢旺长初始期、新梢旺长期、新梢缓长期分别进行整株13C标记,72小时后,整株解析为叶、梢、根三部分,进行15N、13C测定。样品全氮用凯氏定氮法测定,15N丰度用ZHT-03质谱计测定。13C丰度用DELTA V Advantage同位素比率质谱仪测定。【结果】1)中、高氮水平的施肥处理可在不同程度上提高整株及叶片干物质量和新梢长度。新梢旺长初始期和新梢缓长期嘎啦幼苗整株干物质量、新梢旺长期叶片干物质分配比率在中、高氮水平处理间差异不显著,中氮水平经济有效。新梢旺长期以后新梢长度以中氮>高氮>低氮,三者间差异性显著,中氮处理有利于新梢生长。2)在新梢旺长初始期,低氮处理植株叶片15N分配率达50%,比其他处理高出13个百分点左右,表明低氮处理更多的氮被叶片所利用,中氮和高氮处理间差异不显著,说明在本试验施氮条件下中氮供应水平已能满足氮素营养需求。3)新梢旺长期和新梢缓长期幼苗13C固定量均以中氮处理最高,新梢旺长初始期3个处理间根系13C分配率中氮>高氮>低氮,表明中氮处理有利于碳同化物在嘎啦幼苗中的分配。4)不同施氮量处理的嘎啦幼苗,15N利用率随施氮水平提高而降低,高氮处理对碳同化物分配没有显著贡献。【结论】低、中、高氮不同处理新梢缓长期碳同化物在各器官间的分配比较均衡,氮素水平不能影响碳同化物的分配。盆栽试验表明,中氮水平在保证营养供应的同时,能够促进新梢生长和树势健壮。 【Objective】 By using 15N and 13C isotope tracing techniques, the growth, the distribution of nitrogen and carbon and the utilization characteristics of Gala seedlings under different nitrogen rates were studied in order to provide the basis for reasonable fertilization of apple production. 【Method】 Two-year-old pots of Gala seedlings were treated with three nitrogen levels of low, medium and high, and simultaneously with 15N labeling. At the initial stage of shoot growth, the shoots of new shoots were long-term and new shoots were long-term, respectively. After 72 hours, the whole plant was analyzed as leaves, shoots and roots, and 15N and 13C were measured. Sample nitrogen was determined by Kjeldahl method, and 15N abundance was determined by ZHT-03 mass spectrometer. 13C abundance was measured using the DELTA V Advantage Isotope Ratio Mass Spectrometer. 【Result】 1) The medium and high nitrogen fertilization treatments could improve the dry matter mass and shoot length of the whole plant and leaves to varying degrees. There was no significant difference in the dry matter weight of shoots between the shoots of young shoots and young shoots in the long-term and medium-high nitrogen treatments. The mid-level of nitrogen was economical and effective. After long shoots, the shoot length varied from middle to high to low to high, and the difference among the three was significant. The treatment with medium nitrogen was beneficial to shoot growth. 2) At the initial stage of shoot length, the 15N allocation rate of low-N treatment plants was 50% higher than that of other treatments, indicating that more nitrogen was used by leaves under low N treatment. Medium N and high N There was no significant difference between treatments, which indicated that the nitrogen supply level in this experiment could meet the demand of N nutrition. (3) The fixed 13C shoots of shoots with long shoots and shoots were the highest with medium N, and the 13C distribution rates of the three treatments at the initial shoots of shoots were high> high> low nitrogen> Conducive to the distribution of carbon assimilates in Gala seedlings. 4) Under different nitrogen application rates, the utilization rate of 15N decreased with the increase of N application rate, but no significant contribution of N application to carbon assimilation distribution. 【Conclusion】 The distribution of slow-growing carbon assimilates in different shoots with low, medium and high nitrogen treatments is more balanced among organs, and the nitrogen level can not affect the distribution of carbon assimilates. Pot experiments show that the level of nitrogen in the supply of nutrients to ensure the same time, can promote shoot growth and robust tree vigor.