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Uncoupling nitrogen requirements for spring growth from root uptake in a young evergreen shrub ( Rhododendron ferrugineum )
Author(s) -
Lamaze T.,
Pasche F.,
Por A.
Publication year - 2003
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2003.00830.x
Subject(s) - evergreen , shoot , shrub , biology , botany , nitrogen cycle , cycling , nitrogen , population , agronomy , ammonium , horticulture , chemistry , history , demography , organic chemistry , archaeology , sociology
• Internal cycling of nitrogen (N) was investigated in a subalpine field population of the evergreen shrub Rhododendron ferrugineum during spring growth.• The foliar nitrogen of 5‐yr‐old‐plants was directly labeled with 15 N and subsequently traced to all plant compartments. In addition, 15 N‐ammonium uptake was estimated in glasshouse experiments.• Before shoot growth, redistribution of 15 N occurred in the plant without net N transfer. During spring development, the decreases in both leaf 15 N and total N were almost identical in terms of percentage, and most of the 15 N withdrawn from the leaf compartments was recovered in the growing shoots. Net changes in the N contents of the various leaf and woody compartments indicate that internal remobilization (especially from 1‐yr‐old leaves) could have met most of the N needs of new shoot growth. Simultaneously, the rate of mineral N uptake was very low.• Thus, leaves in young plants provide N for new shoots (by contrast with old individuals) and allow, with woody tissues, almost complete uncoupling of N requirement for spring growth from root uptake.