Cultivars of Olive (Olea europaea L.) have different ability for adaption to saline environments. Salinity is one of the major factors limiting plant growth and development. The aim of this research was to study the salinity status tolerance of two olive cultivars: ‘Zard’ and ‘Shiraz’ and also the possibility of using gibberellin to increase plant salt tolerance. Treatments were different concentrations of sodium chloride: 0, 50, 100 and 200 mg L-1, which were added to the pots via irrigation water, and foliage application of gibberellin (GA3) at 0, 10 and 100 mg L-1, which were applied one month after salinity treatments on plants. The results showed that increasing salinity declined leaf area; shoots and roots length; leafs, shoots and roots fresh and dry weights, and increased the amount of leaf proline, and leaf and roots Na+ and Cl-. Application of gibberellin reduced sodium and chloride concentrations in plants, but increased the amount of potassium and chlorophyll. The rate of Na+ accumulation in leaves and roots was lower in ‘Shiraz’ than in ‘Zard’. In different levels of sodium chloride, gibberellin increased the synthesis and accumulation of proline in two cultivars, but this increase was more pronounced in ‘Shiraz’. ‘Shiraz’ showed more vegetative growth than ‘Zard’
