Influence des réserves azotées sur la formation des feuilles d’Alnus glutinosa et ses conséquences dans l'estimation de la fixation d'azote

Publisher Website
Google Scholar
Abstract
The influence of nitrogen reserves on leaf formation of 5- to 6-year-old plants of Alnus glutinosa (L.) Gaertn. was investigated using a 15N labelling method. Nitrogen reserves were derived essentially from the root system and along with N fixation by Frankia, supported the growth of the young leaves. The reserves represent 10% of the total nitrogen in the leaves at the end of the growing period under natural or environmentally controlled conditions. The percentage of fixed nitrogen in alder leaves was estimated to be 87% taking into account the nitrogen reserves and using the isotopic comparison with a nonfixing plant (Populus alba L.). Several conditions requiring the use of 15N methods to estimate the symbiotic nitrogen fixation by Frankia were formulated. The selection of samples for analysis must be from the most recently formed leaves at the end of the growing season to avoid the influence of nitrogenous reserves. Key words: nitrogen reserves, Alnus glutinosa, Populus alba, Frankia, 15N fixation.