Water stress, yield and oil characteristics of partial rootzone drying and deficit irrigated very-high density olive orchard (Olea europaea L. 'Arbequina')

Four irrigation treatments were applied in a commercial, very-high density (VHD) olive orchard in the area of the 'Alto Tavoliere' (Province of Foggia, Apulia, Italy). The treatments consisted of: T (100% water consumption by plants NDASH 1 dripper line; control); D (50% water consumption - 1 dripper line); P (100% water consumption - 2 dripper lines with partial rootzone drying (PRD)); PD (50% water consumption - 2 dripper lines with PRD). Pre-dawn leaf water potential (Ψ_pd), the diurnal pattern of stem water potential (Ψ_stem) and stomatal conductance (g_s) were measured as indicators of the stress level of treatments. Vegetative-productive balance were evaluated through shoot length and yield per plant in terms of fruit and oil production. All treatments have provided extra virgin olive oils that have been characterized in terms of fatty acid composition and phenolic fraction. Water stress indices and WUEs calculated for the compared irrigation treatments showed that olive trees tolerate substantial deficit of irrigation intakes even when grown with the very-high density system.