Morphological and physiological responses to drought stress of carob trees in Mediterranean ecosystems

The greatest failure rate of reforestation programs is basically related to water deficit, especially at the seedling stage. Therefore, main objective this work investigate responses three accessions carob trees (Ceratonia siliqua L.) with 2-year-old from different climate regions drought generated by four treatments: Tc (250 mm), T1 (180 T2 (100 and T3 (50 mm). first accession (A1) comes protected national park Ichkeul in northern Tunisia. This zone belongs bioclimatic sub-humid second (A2) Melloulech, located center-east Tunisia, belonging semi-arid third (A3) mountain Matmata, south hyper-arid experiment was undertaken a greenhouse. Gaz exchange indices (net photosynthesis (A), stomatal conductance (gs), transpiration (E), internal CO2 concentration (Ci)) were determined. Predawn (Ψpd) midday (Ψmd) leaf potentials, relative soil content (SWC), morphological parameters (plant height (H), number leaves (NL), leaflets (Nl), branches (NB)) estimated. results showed that significant differences (P<0.001) found between physiological each accession. highest growth potential recorded for treatment both A1 A2. Significant decreases gs, E, Ci, SWC increases stress applied T3. Positive correlations Ψpd all studied accessions. Ψmd decreased as increased, ranging −0.96 −1.50 MPa sunrise −1.94 −2.83 midday, respectively, under control treatments. C. responded through exhibiting changes their behavior. Both A2 greater tolerance than A3. These seedlings exhibit adaptive mechanisms such avoidance, which are aimed reducing transpiration, limiting growth, increasing root exploit more water. can be recommended ecological restoration Mediterranean ecosystems.