Several reports on annual plants have already shown the involvement of epigenetic modifiers such as DNA methylation in their adaptation to abiotic stresses.* Nevertheless, the genotypic variations of epigenetic modifiers, their possible correlations with morphological traits and the impact of water deficit have not been described for perennial plants.* Six genotypes of Populus deltoides × P. nigra were subjected or not to a moderate water deficit treatment. Various morphological traits such as the height of the plants, their biomass and the total leaf area were measured to characterize the productivity in both conditions. Levels of DNA methylation, histone acetylation and the activities and isoform accumulation of the corresponding enzymes were measured at the shoot apex, the site of morphogenesis. Genotypic variation was observed for the morphological traits and the epigenetic variables and correlations were established among them. Genotypic variation for DNA methylation was detected in hybrid poplars. A positive correlation was demonstrated between DNA methylation percentage and productivity under well watered conditions.* While there was a general decrease of growth for all genotypes in response to a moderate water deficit, genotypic dependant variations of DNA methylation were found suggesting different strategies among hybrids.