Assessing water stress in a hedgerow olive orchard from sap flow and trunk diameter measurements

Abstract

We used sap flow and trunk diameter measurements for assessing water stress in a high-density ‘Arbequina’ olive orchard with control trees irrigated to replace 100 % of the crop water needs, and 60RDI and 30RDI trees, in which irrigation replaced ca. 60 and 30 % of the control, respectively. We calculated the daily difference for both tree water consumption (\( D_{{E_{\text{p}} }} \)) and maximum trunk diameter (DMXTD) between RDI trees and control trees. The seasonal dynamics of \( D_{{E_{\text{p}} }} \) agreed reasonably well with that of the stem water potential. We identified peculiarities on the response \( D_{{E_{\text{p}} }} \) to changes in water stressing conditions, which must be taken into account when using the index. An analysis of the water stress variability in the orchard is required for choosing the instrumented trees. The reliability of the DMXTD index was poorer than that of \( D_{{E_{\text{p}} }} \). The maximum daily shrinkage (MDS) was not a reliable water stress indicator.