Quantifying the photosynthesis limitation imposed by deficit irrigation in olive trees with a novel methodology based on measurements of sap flux density

Abstract

With the ultimate goal of achieving more resilient agricultural systems through deficit irrigation practices managed with a reliable and sensitive indicator of water stress, we conducted an experiment in olive trees with the following specific objectives: (1) to calibrate and validate a method to estimate stomatal conductance (gs) and photosynthesis (AN) automatically based on sap flux density measurements (Js) measurements and (2) to quantify the AN limitations produced by soil water content and vapor pressure deficit in a super-intensive olive orchard. Results show that gs can be determined from Js measurements directly and that the approach is sensitive enough to allow us inferring how stomata respond to soil water content controlled by irrigation and vapor pressure deficit and quantify their limitation on AN. The main advantages of this method are that it provides absolute values of gs, with physiological meaning to interpret plant water stress and that AN limitation imposed by deficit irrigation can easily quantified from the calculated values.