Chilean journal of agricultural research
versão On-line ISSN 0718-5839
JARA-ROJAS, Francisco et al. Model Validation for Estimating the Leaf Stomatal Conductance in cv. Cabernet Sauvignon Grapevines . Chilean J. Agric. Res. [online]. 2009, vol.69, n.1, pp. 88-96. ISSN 0718-5839. http://dx.doi.org/10.4067/S0718-58392009000100011.
The coupled model of assimilation and stomatal conductance (A-gs) was evaluated to estimate leaf stomatal conductance of a drip-irrigated vineyard (Vitis vinifera L. cv. Cabernet Sauvignon) located in the Pencahue Valley (35º22 S, 71°47 W, 150 m.a.s.l.), Maule Region, Chile, during the 2003-2004 and the 2004-2005 growing seasons. Additionally, a calibration of the three parameters mesophyll conductance (gm), maximum specific humidity (Dmax) and coupled factor (f0) was applied on vines growing in 35 L pots. An infrared gas analyzer was used to calibrate and evaluate the A-gs which allowed simultaneous measuring of the leaf net CO2 assimilation (A) and stomatal conductance (gs) in 2 to 3 h intervals of time. The calibration indicated that the gm,, Dmax and f0 values were 1.15 mm s-1, 52.31 g kg-1 and 0.90, respectively. The validation in the drip-irrigated vineyard indicated that the A-gs model was able to estimate the leaf stomatal conductance with a root mean square error (RMSE) of 0.05 mol m-2 s-1, model efficiency of 61% and agreement index of 90%. The sensitivity analysis indicated that the A-gs model is affected considerably by the gm, Dmax and f0 parameterization.
Palavras-chave : A-gs model; photosynthesis; mesophyll conductance; stem water potential; sensitivity analysis.