Water stress indicators during one stress cycle in an intensive olive orchard

The identification of a reliable and practical water stress indicator and the corresponding threshold value, for irrigation scheduling, is a classical concern in water management in agriculture. This is not well solved for woody crops, especially those not traditionally irrigated, usually with large roots systems. Aiming to contribute to these studies, we measured water fluxes and some water stress indicators in an olive grove in south Portugal, during successive stress cycles. We report the first preliminary results during a stress cycle in August-September 2011, using sap flow, leaf water potential at predawn, stem diameter variations and soil water content, from which some indicators were derived. From the preliminary information obtained we could not identify a threshold value but very good relationships were found, between the selected automated and not automated variables, useful for farmers and engineering applications. These first encouraging results need confirmation and further analysi