Midday stem water potential as a useful tool for estimating irrigation requirements in olive trees

Abstract

Irrigation scheduling of fruit trees according to water balance provided significant differences between locations. In recent years, water status measurements such as water potential have been suggested as irrigation tools in different fruit trees. The aim of this study was to adjust water potential threshold values previously studied and water application approaches that permit the irrigation scheduling of olive trees based on midday stem water potential. The experiments were performed during three seasons (from 2005 to 2007) in two different locations (Badajoz and Ciudad Real) with different weather and cultural conditions. In both locations, the olive orchards were seven years old at the beginning of the experiment but had significantly different canopy development. In Ciudad Real the canopy shaded area at the beginning of the experiment was 15% and the first crop was harvested in 2003. On the other hand, canopy shaded area of the olive orchard in Badajoz experiment was 40% and the first crop was harvested in 2001. Therefore, we assimilated Ciudad Real orchard as young, while Badajoz was mature. Three different irrigation treatments were compared in both locations: Control treatment with traditional water balance as irrigation scheduling and two treatments in which midday stem water potential (SWP) provided the information about water management. In the midday water stem potential irrigation (WI) the threshold value of SWP was -1.2 MPa before the beginning of the massive pit hardening period and -1.4 after this date. Finally, in the deficit treatment (DI) the threshold value of SWP was -2.0 MPa throughout the season. In WI and DI treatment irrigation was applied when SWP reached the threshold value. No significant differences were found between Control and WI in any of the seasons and locations when water potential, leaf conductance, shoot and fruit growth and yield (fruit and oil) were considered. In both locations, the same SWP value in WI treatment produced similar water application as the Control treatment. In DI treatment, shoot growth was significantly reduced in both locations in all the seasons. The SWP in DI trees was clearly affected in both locations, while leaf conductance was only reduced in the Badajoz experiment. In the Ciudad Real experiment no significant differences were found in fruit growth, whereas differences were found in Badajoz. However, yield was significantly reduced in Ciudad Real, but not in Badajoz. WI treatment was successful for no water stress conditions. On the other hand, DI treatment was a mild water stress treatment which reduced yield only in low covert orchard, but not in the ones with almost maximum canopy shaded area. Our work presents an approach for using midday stem water potential in the irrigation scheduling of olive trees. The experiments were performed in two different locations and during three years, in order to establish the usefulness of this approach. The results support that the threshold values suggested for no water stress conditions are the s...

An Index From Sap Flow Records to Schedule Irrigation in Super-High Density Olive Orchards

“…5a,b) evolved according to the IAs applied in each treatment and to the weather conditions. The Ψ stem values in the FI trees were always over -1.4 MPa, a threshold for water stress in olive with high crop load (Moriana et al, 2012). From early July to late August, the 60RDI trees showed lower Ψ stem values than the FI trees.…”

Umbrales Sostenibles De Estrés Hídrico Durante El Endurecimiento Del Hueso en La Producción De Aceituna De Mesa

“…100% de la Evapotranspiración del cultivo empelando para el cálculo los coeficientes de cultivo sugeridos por Fernández et al (2006) para la parcela (Kc=0.7 durante la fase de endurecimiento) y estimando un coeficiente reductor ( anterior pero cuatro semanas antes de cosecha. La aplicación del agua de riego en los tratamientos deficitarios fueron diarios cuando era preciso regary la estimación de las necesidades fue proporcional a la distancia de los valores medidos en planta al umbral considerado (Moriana et al 2012;Girón et al 2015). No realizando ningún riego cuando las plantas estaban mejor hidratadas que los umbrales fijados.…”

Impacts of water stress, environment and rootstock on the diurnal behaviour of stem water potential and leaf conductance in pistachio (Pistacia vera L.)

“…The use of plant water status measurements has been suggested previously as a tool for irrigation scheduling (Shackel et al, 1997;Goldhamer et al, 1999;Moriana & Fereres, 2002), given the fact that the Ѱ x measurement results in an accurate state of the dynamic relation integrated by water stress and environmental conditions (Moriana et al, 2012). The reference to a baseline under well-watered conditions and varying atmospheric situations is required for a correct use of midday/middle-afternoon Ѱ x measurements as indicators in pistachio irrigation scheduling.…”

“…To achieve this goal, the irrigation protocol for stressed treatments was derived from the methodology proposed by Moriana et al (2012) for olive trees and was adapted to pistachio by considering a midday Ѱ x threshold of -1.00 MPa as an index for no water stress conditions;…”