Changes of morphological and physiological markers induced by growth phases in leaves of olive tree (Olea europaea L.) REZEQ BASHEER-SALIMIA1, AGGELOS PATAKAS2, VASSILIOS NOITSAKIS3, ARTEMIOS M. BOSABALIDIS4 and MILTIADIS VASILAKAKIS1 1 Department of Horticulture, 3 Department of Range and Wildlife Science, School of Agriculture, 4 Department of Botany, School of Biology, Aristotle University, 54124 Thessaloniki, Greece, 2 Department of Farm Organization and Managements, University of Ioannina, Greece   Abstract Mechanisms involved in phase change phenomena (juvenility-maturity) in olive plant (Olea europaea L. cv Chondrolia Chalkidikis) were studied at anatomical and ecophysiological levels. Juvenile (JP)-, intermediate-juvenile (IJP) and mature (MP) leaves were obtained from three sources representing the three different stages of plant development including seedlings, two- and three-year-old plants derived from cuttings. JP leaves were generally smaller, thicker and more rounded compared to IJP- and MP leaves. The densities of stomata and non-glandular hairs (scales) at the abaxial leaf surface were relatively lower in JP leaves. Stomatal conductance (Gs) and photosynthetic rate (Pn) were higher. MP leaves were larger, thinner and more elongated. Stomata and non-glandular hairs were significantly denser. A lower relative volume (%) of the palisade parenchyma cells in the mesophyll of MP leaves was registered. Furthermore, a significant reduction of the Gs and Pn values was also observed in the MP leaves. IJP leaves revealed an intermediate leaf size as well as intermediate values of almost all of the conducted physiological measurements. No significant difference was found in the relative volume (%) of the mesophyll spongy parenchyma between the JP- and IJP leaves. The higher photosynthetic rate of the JP leaves could be attributed to differences in the leaf anatomical features, especially of the palisade parenchyma cells.   < back .