Forcing variables in simulation of transpiration of water stressed plants determined by principal component analysis

Abstract

A b s t r a c t. To date, measuring plant transpiration at canopy scale is laborious and its estimation by numerical modelling can be used to assess high time frequency data. When using the model by Jacobs (1994) to simulate transpiration of water stressed plants it needs to be reparametrized. We compare the importance of model variables affecting simulated transpiration of water stressed plants. A systematic literature review was performed to recover existing parameterizations to be tested in the model. Data from a field experiment with common bean under full and deficit irrigation were used to correlate estimations to forcing variables applying principal component analysis. New parameterizations resulted in a moderate reduction of prediction errors and in an increase in model performance. Ag s model was sensitive to changes in the mesophyll conductance and leaf angle distribution parameterizations, allowing model improvement. Simulated transpiration could be separated in temporal components. Daily, afternoon depression and long-term components for the fully irrigated treatment were more related to atmospheric forcing variables (specific humidity deficit between stomata and air, relative air humidity and canopy temperature). Daily and afternoon depression components for the deficit-irrigated treatment were related to both atmospheric and soil dryness, and long-term component was related to soil dryness.K e y w o r d s: Ag s model, net CO 2 assimilation rate, stomatal conductance, common bean INTRODUCTION

Finding behavioral parameterization for a 1-D water balance model by multi-criteria evaluation

“…stomatal functions; leaf area; root depth and distribution, and hydraulic characteristics) and abiotic factors (e.g. soil water availability; climate, and depth to groundwater) (Durigon et al, 2016).…”

“…Alternatively, simulation models are used to estimate transpiration. However, to produce accurate simulations, these usually require on-site parameterization or calibration (Durigon et al, 2016;Vose et al, 2003). Recently, a simple approach was developed by Ayyoub et al (2017) relating the normalized daily sap velocities and the daily reference evapotranspiration (ET0).…”