The aim of the study was to examine how soil type affects subsequent olive tree performance. The experiment was conducted from March to June during two crops seasons (2013 and 2014) in two sites distant of 2 Km and they have different soil type. (i) Sandy soil (1.4% organic matter content, with a water content of 12% at field capacity and 6.5% at the wilting point, and (ii) clay loam soil (0.8% organic matter content, with a water content of 15% at field capacity and 7.5% at the wilting point). The two sites have also noted different levels of olive production (25 and 43 kg/tree for sandy soil site and clay loam soil site, respectively) and were located in Sfax in the south of Tunisia (34°3'N; 10°20'E). Twenty-year-old olive trees (Olea europaea L. cv. Chemlali) spaced 7 m × 7 m were subjected to all common olive cultivation practices. Changes in leaf water potential (Ψl), total chlorophyll concentration, gas exchange and soluble sugars were studied in two sites of ‘Chemlali’ olive cultivar with different soil type (sandy and clay loam soil) and with noted different levels of olive production (25 and 43 kg/tree for sandy soil site and clay loam soil site, respectively). Accompanying the changes in leaf water status, all the monitored trees reduced leaf stomatal conductance (gs), transpiration (E) and photosynthetic rate (A) throughout the summer, mirroring the decrease in the soil moisture. However, trees grown in clay loam soil showed higher performance due to higher water availability than trees grown in sandy soil. Soluble sugar content was also higher in the leaves of trees grown in the sandy soil site. These results showed that soil type is a factor influencing the ecophysiological response of olive tree in the dry climate of Tunisia.

Keywords: Photosynthesis, Olea europaea L., Stomatal conductance, Soil type, Tree performance.