Modulation of leaf physiology by age and in response to abiotic constraints in young cuttings of two Populus deltoides P. nigra genotypes Nicolas Marron, Franck Brignolas, Francis M. Delmotte and Erwin DreyerAnn. For. Sci., 65 4 (2008) 404DOI: https://doi.org/10.1051/forest:2008016