冬枣果实硬核期对15N尿素吸收、分配及再利用特性研究

以盆栽冬枣为试材，研究了冬枣果实硬核期土施¹⁵N尿素条件下N的吸收、分配和再利用特性.结果表明，果实膨大期,细根中的肥料氮比率（Ndff%）最高为10.64%，其次为新生营养器官.果实采收后，叶片和枣吊中的¹⁵N回撤；翌年萌芽前，粗根中的Ndff%最高（3.69%）；盛花期，新生营养器官（当年生枣头枝、枣吊、叶片和花）中的Ndff%最高.果实硬核期施肥后，当年根系吸收的¹⁵N尿素主要用于营养生长（叶片、枣吊、根系），回撤¹⁵N优先贮藏于根系，休眠季节根系（54.01%）贮藏¹⁵N略高于地上部器官(45.99%)，主要的¹⁵N贮藏器官为粗根(38.61%).地上部枝干中的贮藏¹⁵N从采果后到萌芽前含量变化剧烈，可作为贮藏¹⁵N营养诊断的“靶器官”，同期粗根中贮藏¹⁵N变幅较小，属长期 “库”.贮藏¹⁵N具有就近利用的特性，其分配随生长中心的转移而转移.

Absorption and distribution of nitrogen from 15N labelled urea applied at core-hardening stage in winter jujube

The study with pot experiment showed that at the rapid-swelling stage of winter jujube fruit,the percent of nitrogen derived from fertilizer(Ndff%) was the highest(10.64%) in fine roots,followed by new-growth nutritive organs.The absorbed urea-()~(15)N decreased in leaves and deciduous supers,and accumulated preferentially in root systems after harvest.The Ndff% in coarse roots was the highest(3.69%) before budding stage,while that in new-growth organs(new branches,deciduous supers,leaves and flowers) was the highest at full-blooming stage.The urea-()~(15)N applied at core-hardening stage mainly allocated in nutritive organs(leaves,deciduous supers,roots) in the first year,with the distribution rate 54.01% in root systems in winter,which was higher than that in branches(45.99%).The()~(15)N stored in main branches changed drastically from post-harvest to budding stage.Main branches could be regarded as the 'target organs' of N storage,while coarse roots were the 'long-term sink' of N storage.The N reserve distributed preferentially in contiguity organs,and the distribution center changed with the growth and development of winter jujube in next spring.