Effects of irrigation and water regime in super-intensive olive orchard in Alentejo

Abstract

This study characterizes the effects of a typical farmer irrigation management and one of deficit irrigation imposed to a hedgerow olive orchard (1, 35 x 3,75 m) in the region of Évora, Southern Portugal on a Eutric Cambisol soil (FAO, 1998). The two irrigation regimes and their effects on tree transpiration, soil water content and stem and leaves water potential, a physiological parameter indicator of plant water stress, are analysed.

With deficit irrigation DI imposed after pit fruit hardening, it was observed a progressive reduction on the values of tree transpiration, stem and leaf water potential and soil water content predominantly towards the end August and September. For the normal irrigation treatment (FI) transpiration values slightly declined for the months of July and August, although less than the ones for treatment DI. Results obtained with the big leaf model of Penman-Monteith (Jones, 1992) and bulk canopy conductance model of Orgaz et al. (2007) indicate that once validated they can be used to predict the transpiration of non-stressed hedgerow olive orchards in Alentejo. Predicting transpiration with the remotely sensed vegetation index NDVI proved difficult for lack of a strong correlation between the two parameters.