Long-term effects of partial root-zone drying (PRD) on yield, oil composition and quality of olive tree (cv. Chemlali) irrigated with saline water in arid land

• Long-term effect of partial root-zone drying with saline water on olive yield.
• Long-term use of saline water increased yield and slightly reduced oil content.
• Irrigation induced a slight increase in oil acidity, K232, K270 and oleic acid.
• Irrigation regimes affected chlorophyll, carotenoids, phenols and oil stability.
• Partial root-zone drying seemed to assure sustainable long-term olive performance.

Long-term effects of partial root-zone drying (PRD) irrigation technique using saline water (6.7 mS cm−1) on olive yield and olive oil composition were investigated. Three irrigation levels were considered: (i) full irrigation (control); (ii) PRD15 and PRD30 irrigated with 50% of water of the control applied on one side and switched every 15 and 30 days, respectively; and (iii) rain-fed conditions. Results showed that accumulated yield significantly increased and oil content decreased with applied irrigation water. Irrigation induced a slight increase in free oil acidity, K232, K270 and oleic acid in contrast to rain-fed treatment. However, it significantly lowered the levels of chlorophyll, carotenoids and phenols, and caused decreases in oil stability as well. Long-term use of saline water to irrigate olive trees significantly improved fresh yield compared to rain-fed treatment, with slight reduction of oil content and olive oil composition. PRD strategy using saline water seems to ensure sustainable long-term olive yield and quality with less salt accumulation in the soil.