Nutrient retranslocation from senescing foliage to perennial organs is critical for nutrient conservation and a mechanism of plant adaptation to low-fertility soils. And it has been well documented for evergreen species and for deciduous broadleaf tree species. Meanwhile, subirrigation (SI) and fertilization are used to improve the production efficiency of seedlings, however, little is known about how retranslocation in deciduous conifer seedlings is affected by SI or soil fertility. We fertilized Larix principis-rupprechtii Mayr seedlings with 50, 100, and 150 mg N per seedling using SI and overhead irrigation (OI). Seedling growth and nutrient status, at both pre-senescence (T1) and post-abscission (T2) moments, and growing media electrical conductivity were measured to (1) explore relationships between foliar nutrient retranslocation and (a) growth, (b) nutrient status, and (c) media fertility, and (2) examined how these are affected by irrigation method and fertilizer rate. Fertilizer rate and irrigation method had little effect on seedling growth, with the exception of root mass, but N, P, and K concentrations increased with increasing soil fertility and both concentrations and contents were greater under SI compared to OI. Foliar N and K retranslocation was lower under SI compared to OI across all fertilizer rates, while foliar P retranslocation was lower only at the highest fertilizer rate for SI-seedlings. For OI-seedlings, retranslocation was unaffected by fertilizer rate, with average N, P, and K retranslocation efficiencies of 71%, 29%, and 55%, respectively. However, retranslocation in SI-seedlings declined as fertilizer rates increased. Foliar nutrient retranslocation directly correlated with seedling biomass accumulation over the growing season (up to T1) and inversely correlated with soil fertility, shoot biomass accumulation during hardening (from T1 to T2), and T1 nutrient concentration in roots (N, P, and K) and stems (N and K). Understanding nutrient retranslocation dynamics for deciduous woody plants informs more effective nutrient management regimes for seedling production under SI.

养分从衰老的叶子向多年生器官的迁移对于养分养护和植物适应低肥力土壤的机制至关重要。对于常绿树种和落叶阔叶树种，已有很好的记录。同时，通过亚灌溉和施肥来提高幼苗的生产效率，但是，人们对于落叶松针叶树幼苗的再移位如何受到土壤SI或土壤肥力的影响知之甚少。我们对华北落叶松进行了施肥使用SI和高架灌溉（OI），每棵苗中含50、100和150 mg N的Mayr幼苗。测量了在衰老前（T1）和脱落后（T2）时苗的生长和养分状况，以及生长介质的电导率，以（1）探索叶面养分迁移与（a）生长之间的关系，（b）养分状况；（c）培养基肥力；（2）研究了灌溉方式和施肥量如何影响这些肥力。施肥速率和灌溉方式对幼苗生长的影响很小，除了根系质量外，但氮，磷和钾的浓度随土壤肥力的增加而增加，SI下的浓度和含量均高于OI。在所有肥料用量下，SI下的叶面氮素和钾素的重新分配比OI更低，而仅SI幼苗的最高肥料施用率下，叶面磷的重新转运较低。对于OI幼苗，重新分配不受肥料用量的影响，平均N，P和K的重新分配效率分别为71％，29％和55％。但是，随着肥料用量的增加，SI幼苗的重新转运减少了。叶面养分的重新分配与生长季（直至T1之前）幼苗生物量的积累直接相关，而与土壤肥力，硬化过程中茎生物量的积累（从T1到T2）和根部的T1养分浓度（N，P和K）成反比。 ）和词干（N和K）。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。对于OI幼苗，重新分配不受肥料用量的影响，平均N，P和K的重新分配效率分别为71％，29％和55％。但是，随着肥料用量的增加，SI幼苗的重新转运减少了。叶面养分的重新分配与生长季（直至T1之前）幼苗生物量的积累直接相关，而与土壤肥力，硬化过程中茎生物量的积累（从T1到T2）和根部的T1养分浓度（N，P和K）成反比。 ）和词干（N和K）。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。对于OI幼苗，重新分配不受肥料用量的影响，平均N，P和K的重新分配效率分别为71％，29％和55％。但是，随着肥料用量的增加，SI幼苗的重新转运减少了。叶面养分的重新分配与生长季（直至T1之前）幼苗生物量的积累直接相关，而与土壤肥力，硬化过程中茎生物量的积累（从T1到T2）和根部的T1养分浓度（N，P和K）成反比。 ）和词干（N和K）。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。随着肥料用量的增加，SI幼苗的重新转运减少。叶面养分的重新分配与生长季（直至T1之前）幼苗生物量的积累直接相关，而与土壤肥力，硬化过程中茎生物量的积累（从T1到T2）和根部的T1养分浓度（N，P和K）成反比。 ）和词干（N和K）。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。随着肥料用量的增加，SI幼苗的重新转运减少。叶面养分的重新分配与生长季（直至T1之前）幼苗生物量的积累直接相关，而与土壤肥力，硬化过程中茎生物量的积累（从T1到T2）和根部的T1养分浓度（N，P和K）成反比。 ）和词干（N和K）。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。根（N，P和K）和茎（N和K）中的T1营养素浓度。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。根（N，P和K）和茎（N和K）中的T1营养素浓度。了解落叶木本植物的养分迁移动态可为SI下的幼苗生产提供更有效的养分管理方案。