ION SELECTIVITY IN YOUNG PLANTS OF OLEA EUROPAEA L. UNDER SALINITY STRESS CONDITIONS

Olive trees are moderately tolerant of salinity and plantations have recently been established in arid and marginal areas. In Argentina, most of the olives are located in non-traditional irrigated areas where the soil salinity is high due to arid conditions and lack of precipitation. The aim of this study was to assess the effects of salinity on growth of two cultivars, Olea europaea L. ‘Barnea’ and ‘Arbequina’, and link these effects to ionic homeostasis mechanisms. Sixty replications of each cultivar were grown in pots containing a sand, perlite, peat (1:1:1) substrate, and irrigated with NaCl solutions. The saline treatments consisted of three NaCl solutions (4, 6 and 8 dS/m, equivalent to 25, 37.8 and 50 mM NaCl) during the first season and 6 and 8 dS/m NaCl in the second season. In both seasons, control treatment was a 2 dS/m solution. Measurements of morphometric parameters (height, number of leaves) and chemical parameters (ionic content) were carried out periodically. The results indicated that the growth of both cultivars decreased with the exposure to increasing levels of salinity, with ‘Barnea’ being the most adversely affected. ‘Barnea’ accumulated significantly more Cl^ˉ in leaf tissue than ‘Arbequina’, and had less shoot growth and a greater percentage of leaf damage. The results indicated ‘Arbequina’ is an ion-selective cultivar, suggesting that there is a mechanism for exclusion of Cl^ˉ at root level that prevents entry and accumulation of Cl^ˉ into the leaf.