The Effect of Drought and Saline Water on the Nutritional Behaviour of the Olive Tree (olea Europaea L.) in an Arid Climate

Irrigation with saline water is becoming a frequent practice in arid areas. This alternative may substitute for water scarcity. The role of nutrient uptake in olive trees is reflected in their metabolic functions to mitigate against drought and saline conditions. This study investigated the adaptive strategies of olive trees, with regard to their nutrient and water uptake under combined salt and water stress. The stress factors were managed by irrigation with tap water (EC=2.46 mS/cm) and saline water (EC=7.5 mS/cm) in an arid climate. Potassium (K+) and calcium (Ca2+) play an important role in the physiological performance of olive trees and improves their adaptation under drought and saline conditions. The highest levels of K+ were observed at 1 and 3.22% (% leaf dry matter) with both saline water and DRY treatments after re-watering, with a recovery of 56%. The Ca2+ content reached 1.57% (% leaf dry matter) in plants subjected to saline water which was higher than in the DRY regime (2.2%). During severe drought, olive trees maintained their mineral status by increasing nitrogen (N) content, leaf starch and soluble carbohydrate profiles. In trees irrigated with saline water and under DRY conditions, a high level of proline as a stress indicator was accompanied by an increase in total phenol content, malondialdehyde (MDA), and hydrogen peroxide (H2O2) concentrations. The physiological performance improved moderately under the saline conditions as compared to DRY conditions. Tolerance to water shortage and salt stresses were linked to the accumulation of organic molecules and mineral elements in leaves.