Physiological and biochemical traits of different olive tree cultivars during salt stress

Cultivated olive (Olea europaea L.) is a major tree crop in the Mediterranean region and is moderately salt tolerant. Knowing that the availability of non-saline water will decrease dramatically in the future because of climate change, the identification of saline-resistant cultivars become of particular interest, especially for those cultivation systems, which require large quantities of water. In the present work olive pot grown plants of the cultivars 'Royal de Cazorla' and 'Arbequina' were stressed with 100 and 200 mM NaCl. During the experiment the leaves gas exchanges, chlorophyll and proline content and the activity of glutathione reductase (GSH), catalase (CAT) were monitored. In the two cultivars a decrease of net photosynthesis (Pn) and stomatal conductance (gs) accompanied by an increase in sub-stomatal CO2 concentration (Ci) was observed. The increase of antioxidant enzymes activity in stressed plants indicates the presence of a high oxidative stress. In general, 'Arbequina' showed a lower tolerance to salt stress and died after 220 days of treatment while 'Royal' showed a greater resistance, probably due to a higher expression of CAT and GSH in non-stress conditions.