Abstract

In drip-irrigated olive orchards, tree transpiration (T) is the most important component of the actual evapotranspiration (ETa) under semi-arid conditions. For this reason, the determination of T is a very important issue to apply a correct irrigation scheduling. Thus, the objectives of this study were to determine T, and to evaluate the relations of: i) T and ETa, ii) T and solar radiation (SR), and iii) T and vapor pressure deficit (VPD). A field study was carried out to measure T and ETa of a commercial super intensive hedgerow (5 m between rows and 1.3 m between plants) 3-year-old drip-irrigated olive orchard (Olea europaea L. 'Arbequina') located in Pencahue valley, Maule Region, Chile (35 degrees 23'LS; 71 degrees 44'LW; 96 m a.s.l.). Measurements of T and ETa were done using sap flow (SF) sensors and an eddy correlation system (EC), respectively. The heat pulse velocity method (HPV) was used to obtain T every 30 min. The results show that the diurnal trend of T was similar to those of ETa, VPD and SR for most of the study days. Also, on a daily basis, mean values of T under sunny days were around 2.6 L plant(-1) day(-1), which represent about 67% of total olive orchard water requirements.