Mechanism of Salinity Tolerance in Oleaster and Cultivated Olive Tree: Physiological and Morphological Characterization of the Foliar System

Abstract

Aims: The olive tree has a positive impact on the environment and help to the conservation of the landscapes. Better adapted to aridity conditions around the Mediterranean, it is a fastening element for the rural population. Oleaster (the wild olive tree) represents a valuable phyto-resource for the improvement of the olive trees varieties. This work focuses on determining the physiological and morphological response of the foliar system in cultivated olive tree (variety Sigoise) and Oleaster in condition of different salinity level of the irrigation water (by increasing NaCl concentration). Methodology: The experiment took place in a greenhouse with a well controlled condition. The experimental plan is in a complete randomization of two factors (salinity and species) and three salinity levels (treatments); plants without NaCl application were used as control. The plant material (young 2-year-old olive seedlings) was selected and brought from a crop nursery. The experimentation started by the irrigation of the control plant with a nutrient solution. About the other treatments, the tree seedlings received a nutrient solution fortified by the addition of the NaCl with increasing doses of 75,100 and 150mM of the NaCl. Four repetitions are being done according to the field capacity. Results and Conclusion: The study covered the variation of the relative water content in leaves as well as the leaf surface, stomata density, the wax rate on the upper foliar epidermis and their internal anatomy. According to the achieved results, the relative water content of the treated plants decreased when compared to the control plants. The same was found for leave surface and stomata density. On the other hand, the wax rate increased in the salt stress situations compared to the control plant and to the bulbous form cells’ number and the wood vessels.