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Modified Penman-Monteith model shows changes in stomatal conductance in apple saplings after treatment with mixture of bioregulators

Kullaj, E., Avdiu, V., Thomaj, F.
Acta horticulturae 2017 no.1177 pp. 312-318
apples, benzyladenine, canopy, cultivars, ecophysiology, equations, gauges, models, rootstocks, sap flow, saplings, stomata, stomatal conductance, stomatal movement, vapor pressure
Apple saplings of cultivar 'Gala Galaxy' on M.9 rootstock were treated with Progerbalin (GA4+7 + 6-benzyladenine) and then assessed for canopy transpiration and stomatal conductance (gs) using a modified Penman-Monteith (P-M) model and sap flow gauges. The model was based on a complex parameterized of the P-M equation re-written to include gs as the function of radiation (R) and vapor pressure deficit (VPD). With the model we calculated the dynamics of stomata conductance and compared calculated conductance of treated trees to untreated controls. Transpiration data were also calculated from sap flow measurements. Stomata response was analyzed showing differences in their stomata behavior due to treatment with the bioregulator. This ecophysiological model of canopy transpiration and stomata conductance could be a valuable tool for studying interrelated physiological functions, particularly for comparing cultivars or various treatments.