Abstract: Compared analyses of the chemical composition of the ramets of three natural populations of Atriplex halimus placed in a common garden were carried out. The study showed a significant variability of chemical and nutritive value between the three Moroccan populations originating from three bio-climate contexts (semi arid, arid and saharan). This variability appears within and between populations according to the sampling date. Ramets from Safi (semi arid bio-climate) and Marrakech (arid bio-climate) showed high contents of crud proteins (21.59 to 25.07% and 19.56 to 25.48% during the humid period and 19.12 to 20.64% and 17.42 to 19.94% during the dry period, respectively). As for the total phosphorus contents, the two populations reached 0.12 to 0.17% and 0.12 to 0.19% during the dry period and 0.25 to 0.31% and 0.21 to 0.32% during the humid period, respectively. Lipid matter levels were high during the autumnal period and estimated respectively at 10.14 to 10.87% and 10.27 to 12.66% for the same populations. The highest contents of fiber (acid detergent fiber: ADF), of crud ash, sodium and calcium were observed during the dry period (June, July, August and October). A highly significant negative correlations (P<0.01) were found between crud protein, fibers (ADF), crud ash, sodium, potassium, calcium and iron. Whereas, a highly significant positive correlation (P<0.01) was detected between crud proteins, phosphorus and lipid fraction.