Irrigation is one of the most important means of increasing olive oil production but little information exists on the responses of olive to variable water supply. Five different irrigation strategies, full irrigation, rain fed, and three deficit irrigation treatments were compared from 1996 to 1999, in Cordoba, southern Spain, to characterize the response of a mature olive (Olea europaea L. `Picual') orchard to irrigation. Crop evapotranspiration (ETc) varied from less than 500 mm in the rain fed to ≈900 mm under full irrigation. The deficit irrigation treatments had ETc values that ranged from 60% to 80% of full ETc depending on the year and treatment. Water relations, and oil content and trunk growth measurements allowed for the interpretation of yield responses to water deficits. In a deficit irrigation treatment that concentrated all its ETc deficit in the summer, stem water potential (Ψx) decreased to -7 MPa but recovered quickly in the fall, while in the treatment that applied the same ET deficit progressively, Ψx was never below -3.8 MPa. Minimum Ψx in the rain fed treatment reached -8 MPa. Yield (Y) responses as a function of ETc were calculated for biennial yield data, given the alternate bearing habit of the olive; the equation are: Y = -16.84 + 0.063 ET -0.035 × 10-3 ET2, and Y = -2.78 + 0.011 ET - 0.006 × 10-3 ET2, for fruit and oil production respectively, with responses to ET deficits being similar for sustained and regulated deficit irrigation. The yield response to a deficit treatment that was fully irrigated during the bearing year and rain fed in the nonbearing year, was less favorable than that observed in the other two deficit treatments.

The influence of full irrigation, double-regulated (RDI) and sustained deficit irrigation (SDI) treatments on almond quality was assessed by analyzing different parameters: sugars, organic acids, antioxidant activity, total phenolic content (TPC), and volatile compounds. Almond quality studies for plants submitted to water stress are scarce, and it is essential to understand the biochemical responses of plants to water stress in maintaining fruit yield and quality. Citric acid, sucrose, antioxidant activity, and TPC were not affected by the application of studied deficit irrigation strategies (DI). An increase in malic acid and a decrease in glucose was observed for stressed samples (T3 and T4), while a higher number of total volatiles compounds was found for moderate RDI (T2). Using deficit irrigation strategies, the almond yield and quality was not changed, and in fact, some parameters, such as glucose and key volatile compounds, slightly increased under moderate RDI. This finding might encourage farmers to implement these strategies and contribute to sustainable agriculture.

No abstract

The use of deficit irrigation techniques on olive orchards is the main trend aiming to optimize water savings while improving functional and sensory characteristics of oils from trees under deficit irrigation techniques. The brand hydroSOStainable has been defined for crops produced under water restriction conditions. HydroSOStainable olive oils obtained under two new regulated deficit irrigation and one sustained deficit irrigation treatments in “Arbequina” olive trees were evaluated by analyzing quality parameters, antioxidant activity, total phenol content, fatty acid profile, volatile compounds, and sensory descriptors. Results showed that some of these irrigation strategies improved the phenol content at “moderate” stress levels, slightly enriched the fatty acid profile (~3.5% increased oleic acid and simultaneously decreased saturated fatty acids), and increased some key volatile compounds and also several key sensory attributes. Therefore, hydroSOStainable olive oil may be more attractive to consumers as it is environmentally friendly, has a higher content of several bioactive compounds, and has improved sensory characteristics as compared to control (fully irrigated) oils.