Uncoupling nitrogen requirements for spring growth from root uptake in a young evergreen shrub (Rhododendron ferrugineum)
Article first published online: 24 JUL 2003
Volume 159, Issue 3, pages 637–644, September 2003
How to Cite
Lamaze, T., Pasche, F. and Pornon, A. (2003), Uncoupling nitrogen requirements for spring growth from root uptake in a young evergreen shrub (Rhododendron ferrugineum). New Phytologist, 159: 637–644. doi: 10.1046/j.1469-8137.2003.00830.x
- Issue published online: 24 JUL 2003
- Article first published online: 24 JUL 2003
- Received: 28 February 2003 Accepted: 6 May 2003; doi: 10.1046/j.1469-8137.2003.00830.x
- Internal cycling;
- leaf 15N labeling;
- root uptake;
- Rhododendron ferrugineum;
- spring growth;
- • 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 15N and subsequently traced to all plant compartments. In addition, 15N-ammonium uptake was estimated in glasshouse experiments.
- • Before shoot growth, redistribution of 15N occurred in the plant without net N transfer. During spring development, the decreases in both leaf 15N and total N were almost identical in terms of percentage, and most of the 15N withdrawn from the leaf compartments was recovered in the growing shoots.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.