作 者：
郑朝霞;王颖;巩庆利;郑伟;赵志远;翟丙年;韩明玉
单 位：
西北农林科技大学园艺学院;西北农林科技大学资源环境学院;农业部西北植物营养与农业环境重点实验室
关键词：
红富士苹果;自根砧;氮素;吸收;分配;利用
摘 要：
【目的】研究不同施氮水平对矮化自根砧红富士苹果幼树氮素吸收、分配和利用的影响,为矮化自根砧苹果园氮素管理提供依据。【方法】采用盆栽试验,以2年生矮化自根砧红富士苹果幼树为试材,利用~(15)N同位素示踪技术,研究三个施氮水平下幼树对氮素的吸收、分配及利用特性。试验设三个处理,每千克土施氮(N)量为0.1 g(N_(0.1))、0.2 g(N_(0.2))和0.3 g(N0.3),分别在春梢停长期(6月23日)、秋梢停长期(8月25日)、养分回流期(9月20日)和落叶前期(10月23日)取全株样品进行氮的分析测定。【结果】至落叶前期,矮化自根砧红富士苹果幼树总干重和根系生物量以N_(0.1)水平最高。不同氮素水平下,植株不同器官从肥料中吸收分配到的~(15)N量对该器官全氮量的贡献率(Ndff)差异较大。氮肥施入至春梢停长期,幼树地上部新生营养器官Ndff值最高;秋梢停长期至落叶前期均以根系的Ndff值最高,同时根部吸收的~(15)N也优先向营养器官运转;树体对氮的吸收征调能力随施氮量的增加而减弱。果树春梢停长期,N_(0.1)处理树体新吸收的氮素可更为快速地转运至新生器官;春梢停长期至养分回流期,叶片~(15)N分配率最大;落叶前期,N_(0.1)处理根系~(15)N分配率(33.8%)显著高于N_(0.2)(17.0%)和N0.3(22.5%)处理,叶片中约37.6%的氮素回流到树体内。随着生育期的推移,树体~(15)N利用率显著提高,至养分回流期各处理~(15)N利用率为N_(0.1)(30.0%)>N_(0.2)(27.9%)>N0.3(21.7%)。春梢停长期至养分回流期,三个施氮水平下树体吸收的~(15)N均占整个生育期氮素吸收的80%或以上。【结论】春梢停长期至养分回流期是矮化自根砧红富士苹果幼树氮素营养需求的关键时期,N_(0.1)处理有利于幼树营养生长和氮素的吸收利用及贮藏,建议生产上应适当控制氮肥的投入,根据果树需肥关键时期合理施用氮肥,满足树体不同生长发育阶段对氮素的需求,提高氮肥利用率。
译 名：
Absorption, distribution and utilization of soil applied ~(15)N-urea in young dwarf rootstock 'Fuji' apple trees
作 者：
ZHENG Zhao-xia;WANG Ying;GONG Qing-li;ZHENG Wei;ZHAO Zhi-yuan;ZHAI Bing-nian;HAN Ming-yu;College of Natural Resources and Environment, Northwest A&F University;Key Laboratory of Plant Nutrition and Agricultural Environment of Northwest of Ministry of Agriculture;College of Horticulture, Northwest A&F University;
关键词：
'Fuji' apple;;rootstock;;nitrogen;;absorption;;distribution;;utilization
摘 要：
【Objectives】Effects of different nitrogen rates on nitrogen absorption, distribution and utilization of young dwarf rootstock ‘Fuji' apple trees were studied to provide scientific basis for nitrogen management of dwarf rootstock apple orchards.【Methods】A pot experiment was carried out using two–year–old dwarf rootstock ‘Fuji' apple trees as materials. Three levels of ~(15)N stable isotopes, 0.1 g/kg(N_(0.1)), 0.2 g/kg(N_(0.2)) and 0.3 g/kg(N0.3), were applied in each trees. The whole seedlings were destructively sampled at the end of spring shoot growth(June 23 rd) and autumn shoot growth(August 25 th), nutrient backflow stage(September 20 th) and early defoliation(October 23 rd). Total nitrogen was determined by high resolution digital colorimeter autoanalyzer, and the ~(15)N abundance was determined by MAT253 mass spectrometer.【Results】At the early stage of defoliation,the total dry weight and roots biomass of dwarf rootstock ‘Fuji' apple trees were maximum under the N_(0.1) level.The contribution rates of nitrogen derived from fertilizer(Ndff) to the total nitrogen contents in different organs were affected by the application rates. The highest Ndff was in the new vegetative organs aboveground at the spring shoot stop growing stage. From the autumn shoot stop growing stage to early defoliation stage, the Ndff of roots was the highest, and the ~(15)N absorbed by roots was preferentiallly distributed to the new vegetative organs.However, the ability of nitrogen uptake of apple trees was weakened with the increase of nitrogen rates.Furthermore, the nitrogen absorbed by trees could be quickly transported to new organs under the N_(0.1) level at spring shoot stop growth. The ~(15)N distribution ratio in the leaves was the highest from spring shoot stop growing to nutrient backflow stage. The ~(15)N distribution ratio of roots under the N_(0.1) treatment(33.8%) was significantly higher than those under the N_(0.2) treatment(17.0%) and N0.3 treatment(22.5%) in the early defoliation stage, while about 37.6% nitrogen in leaves back fluxed in fruit trees. The ratios of ~(15)N utilization increased significantly with the process of growth, and were in order of N_(0.1)(30.0%) > N_(0.2)(27.9%) > N0.3(21.7%) at the nutrient backflow stage. Besides, the ~(15)N absorbed by trees from spring shoot stop growing to nutrient backflow stage accounted for80% or more of the nitrogen uptake during the whole growth periods.【Conclusions】The duration of spring shoot stop growth stage and nutrient backflow stage is the key period of nitrogen requirement for dwarf rootstock ‘Fuji' apple trees. N_(0.1) is suitable for the vegetative growth, nitrogen absorption, utilization and storage of young dwarf rootstock ‘Fuji' apple trees. In practice, nitrogen fertilizer rate should be controlled and applied based on the practical requirement, thus nitrogen utilization rate will be increased.
