The absorption capacity and partitioning of 15n to the major organs of ‘fuji’ apple trees on m26 interstock using 15n-labelled urea in early summer | 矮化中间砧富士苹果初夏土施15N-尿素的吸收分配特性

Chinese. 目的为富士苹果生产合理施氮肥提供理论依据。方法以5年生大田栽培红富士苹果（基砧为秋子，中间砧为M26）为试材，以初夏土施15N-尿素为手段，研究2年不同时期主要器官对15N-尿素的吸收分配特性。结果初夏施肥后1个月，根系吸收了一定量的氮，但对新生器官供应较少。随着物候期的推进，新生器官15N肥分配势逐步增强，其中新梢吸收分配15N能力最强，其次为叶片和果实，采收期根系吸收分配15N能力又显著回升。施肥翌年各主要器官吸收氮来自肥料氮的百分数均显著高于施肥当年。在果实采收期，一年生器官、多年生枝干和根系15N分配率当年分别为23.5%、40.4%、36.1%，翌年分别为27.7%、34.9%、37.4%。结论初夏施氮，主要满足了树体当年后期新梢生长发育对氮的需要，同时利于树体积累贮藏营养。初夏按本试验方法施氮肥，采收期树体的当年氮肥利用率为56.19%。

English. Objective The aim of the study is to provide a theoretical basis for N fertilizer rational application for ‘Fuji’ apple under field conditions. Method The absorption capacity and partitioning of 15N urea of major organs at different phenological stages were conducted using five-year-old field-cultivated ‘Fuji’ apple tree on M26 interstock treated with 15N -urea in early summer. Result The 15N -urea fertilizer was absorbed and transported by root firstly during the first month. The highest amount of 15N uptaken by root occurred at young fruit stage. The 15N absorption mainly contributed to new organs building with the development of plants in a month. The absorption capacity of 15N urea of new organs was higher in shoot, and then in leaf and fruit. The 15N absorption capacity and partitioning of roots was increased again at harvesting stage. The Ndff% of the major organs was higher in the next year than in the first year in fertilizer. At harvesting stage, the total N content and the amounts of 15N transportation to perennial stem were higher than those to new organs and roots. The 15N distribution ratio in new organs, perennial stem and roots were 23.5%, 40.4%, 36.1% in the first year and 27.7%, 34.9%, 37.4% in the second year, respectively. Conclusion The N fertilizer application in early summer mainly contented with the requirement to shoots development in the later season and was beneficial for accumulation of nutrition stored in apple trees. The N utilization efficiency of apple tree at fruit harvesting stage was 56.19% in the current year in this study.