Optimization of irrigation water use in grapevines using the relationship between transpiration and plant water status

Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines

“…While the Sousa et al (2006) study somewhat agrees with results presented in this paper (relationship between midday W l and grapevine water use) those of Patakas et al (2005) and Escalona et al (2002) do not. One possible explanation for the differences between the two latter studies mentioned above and this study could be related to the method and/or technique in which W l was measured.…”

“…The exact technique used to measure W l in the Escalona et al's (2002) paper was not given but based upon the above discussion and the results from the measurements of W l from their study, it can be assumed that they did not bag the leaf blade prior to cutting the petiole, probably resulting in erroneous values. In addition, since W l and W stem are highly correlated with one another in grapevine (Salón et al 2005;Stevens et al 1995;Williams and Araujo 2002;Williams and Trout 2005), it is not surprising that Patakas et al (2005) did not find W l to be correlated with the SF Ti /SF Tl ratio since they did not measure W l as outlined by Turner and Long (1980). Alternatively, measuring grapevine transpiration via the sap flow technique could have underestimated grapevine water use resulting in unreliable values Tarara and Ferguson 2001).…”

“…Leaf W was measured in the Sousa et al (2006) study by enclosing the leaf blade in a plastic bag prior to cutting the petiole (noted in their ''Materials and methods'' section). Patakas et al (2005) only enclosed the leaves in plastic bags after severing the petiole (personal communication). The exact technique used to measure W l in the Escalona et al's (2002) paper was not given but based upon the above discussion and the results from the measurements of W l from their study, it can be assumed that they did not bag the leaf blade prior to cutting the petiole, probably resulting in erroneous values.…”

Comparación de la cámara de presión tipo Scholander modelo Pump-up respecto a la cámara de presión tradicional en vides de mesa

“…Los valores obtenidos por la cámara de presión tipo Scholander tradicional fueron de -0,36 MPa para las "plantas hidratadas" y de -0,81 MPa para "plantas con estrés hídrico"; por su parte, los potenciales hídricos xilemáticos fueron entre -0,35 y -0,81 MPa para las plantas evaluadas con la cámara de presión tipo Scholander modelo Pump-up (Figura 3). Estos potenciales xilemáticos coinciden con algunos investigadores (Williams y Trout, 2005;Patakas et al, 2005;Williams y Baeza, 2007), que determinan a la vid en una condición hídrica óptima con potenciales hídricos xilemáticos menores a -0,7 MPa.…”

“…Entre éstos se encuentran: potencial hídrico basal, potencial hídrico foliar, potencial hídrico xilemático, conductancia estomática, flujo de savia y diámetro del tronco. Éstos permitirían describir cambios en el estado hídrico de la planta integrando condiciones climáticas y del suelo (Naor, 2006;Patakas et al, 2005;Sellés et al, 2002;Choné et al, 2001;Patakas et al, 1997).…”