An index from sap flow records to schedule irrigation in super-high density olive orchards

Regulated deficit irrigation (RDI), recommended for super-high density (SHD) olive orchards, requires a precise control of irrigation. Water must be supplied on the phenological stages when the plant is most sensitive to water stress, but irrigation promotes plant vigour, and excessive growth hampers management in SHD orchards. A reliable water stress indicator is needed, therefore, for the proper management of RDI. Here we present an evaluation of the performance of DEp, an index previously reported by Cuevas et al. (2012). The index is derived from sap flow measurements in RDI trees and in fully irrigated trees used as a reference. We evaluated the index during the irrigation seasons of 2011 and 2012, in an 'Arbequina' olive orchard with 1667 trees ha-1 close to Seville, southwest Spain. The index showed a potential for scheduling RDI strategies, although its reliability decreased on periods of fluctuating atmospheric demand. The required data analyses and data interpretation make the DEp index suitable for well-trained users only.