The effect of deficit irrigation on seasonal variations of plant water use in Olea europaea L.

Abstract

A field experiment on olive trees (Olea europaea L.) was designed with the objective to search for an optimum irrigation scheduling by analyzing the possible effects of deficit irrigation. Treatments were: a non-irrigated control (rainfed) and three treatments that received seasonal water amount equivalent to 33 and 66% of crop evapotranspiration (ET C ) in the period August-September (respectively 33II and 66II), and 66% of ET C from late May to early October (66I-II). Atmospheric evaporative demand and soil moisture conditions were regularly monitored. Irrigation effects on plant water relations were characterized throughout a growing season. Whole-plant water use, in deficit irrigated (66I-II) and rainfed olive trees, was determined using a xylem sap flow method (compensation heat-pulse technique). The magnitude of variations in water use and the seasonal dynamic of water relations varied among treatments, suggesting that olive trees were strongly responsive to both irrigation amount and time. Physiological parameters responded to variations in tree water status, soil moisture conditions and atmospheric evaporative demand. All measurements of tree water status were highly correlated with one another. There was a considerable degree of agreement between daily transpiration deduced from heat-pulse velocity and that determined by calibration using the water balance technique. Deficit irrigation during the whole summer (66I-II) resulted in improved plant water relations with respect to other watering regimes; while, severe regulated deficit irrigation differentiated only slightly 33II treatment from rainfed plants. Nevertheless, regulated deficit irrigation of olive trees after pit hardening (66II) could be recommended, at least in soil, cultivar and environmental conditions of this study.

Cultivation Techniques

“…The capacity to withstand severe and prolonged drought periods, however, is negatively associated with olive tree growth and productivity, owing to the decrease of assimilates under water deficit conditions. Reductions in photosynthetic performance under water stress have also been observed by several authors (Inglese et al, 1999;Patumi et al, 1999;Tognetti et al, 2005;Bacelar et al, 2006;Lavee et al, 2007;Ben Ahmed et al, 2009). …”

Effect of drought stress and selenium spraying on photosynthesis and antioxidant activity of spring barley / Učinek sušnega stresa in škropljenja s selenom na fotosintezo in antioksidativno aktivnost jarega ječmena

“…Our results confirm the great sensitivity of leaf photosynthesis to drought. Reductions in photosynthetic performance under water stress have also been observed by Tognetti et al (2005), Bacelar et al (2006) and Ben Ahmed et al (2009). Following the drought stress, Se-supplemented plants showed a lower reduction in these photosynthetic parameters (A and g s ) in response to drought stress when compared with water-deficit plants.…”

Estimation of Energy Balance Components over a Drip-Irrigated Olive Orchard Using Thermal and Multispectral Cameras Placed on a Helicopter-Based Unmanned Aerial Vehicle (UAV)

“…Traditional methods employ the ETo-crop coefficient approach (ETa = EToˆKc, where ETo is the reference evapotranspiration (mm day´1) and Kc is the crop coefficient) [5,6]. The accurate estimate of ETa or latent heat flux (LE) is an important factor for establishing irrigation strategies such as regulated deficit irrigation (RDI), which has been successfully applied on olive orchards to increase water productivity and olive oil quality [7][8][9][10]. In addition, Cohen et al [11] and Ortega-Farias et al [12] indicated that the site-specific irrigation management (SSIM) can be used as a technical tool to improve water productivity.…”