This study aims to assess the response of Pistacia atlantica Desf. seedlings to water stress under laboratory conditions. A total of 80 seedlings (11 months old) of the same species from two contrasting sites in Algeria: M.d.a (sub-humid with 5 dry months) and Bechar (arid with 12 dry months) were subjected to water stress for 15 and 30 days. Their physiological response was assessed by measurements of leaf water potential, leaf pigment content, chlorophyll fluorescence, and gas exchange. The re