AUTHOR=Wei Zhenhua , Du Taisheng , Li Xiangnan , Fang Liang , Liu Fulai 

TITLE=Simulation of Stomatal Conductance and Water Use Efficiency of Tomato Leaves Exposed to Different Irrigation Regimes and Air CO2 Concentrations by a Modified “Ball-Berry” Model

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00445

DOI=10.3389/fpls.2018.00445

ISSN=1664-462X

ABSTRACT=<p>Stomatal conductance (<italic>g</italic><sub>s</sub>) and water use efficiency (<italic>WUE</italic>) of tomato leaves exposed to different irrigation regimes and at ambient CO<sub>2</sub> (<italic>a</italic>[CO<sub>2</sub>], 400 ppm) and elevated CO<sub>2</sub> (<italic>e</italic>[CO<sub>2</sub>], 800 ppm) environments were simulated using the “Ball-Berry” model (BB-model). Data obtained from a preliminary experiment (Exp. I) was used for model parameterization, where measurements of leaf gas exchange of potted tomatoes were done during progressive soil drying for 5 days. The measured photosynthetic rate (<italic>P</italic><sub>n</sub>) was used as an input for the model. Considering the effect of soil water deficits on <italic>g</italic><sub>s</sub>, an equation modifying the slope (<italic>m</italic>) based on the mean soil water potential (Ψ<sub>s</sub>) in the whole root zone was introduced. Compared to the original BB-model, the modified model showed greater predictability for both <italic>g</italic><sub>s</sub> and <italic>WUE</italic> of tomato leaves at each [CO<sub>2</sub>] growth environment. The models were further validated with data obtained from an independent experiment (Exp. II) where plants were subjected to three irrigation regimes: full irrigation (FI), deficit irrigation (DI), and alternative partial root-zone irrigation (PRI) for 40 days at both <italic>a</italic>[CO<sub>2</sub>] and <italic>e</italic>[CO<sub>2</sub>] environment. The simulation results indicated that <italic>g</italic><sub>s</sub> was independently acclimated to <italic>e</italic>[CO<sub>2</sub>] from <italic>P</italic><sub>n</sub>. The modified BB-model performed better in estimating <italic>g</italic><sub>s</sub> and <italic>WUE</italic>, especially for PRI strategy at both [CO<sub>2</sub>] environments. A greater <italic>WUE</italic> could be seen in plants grown under <italic>e</italic>[CO<sub>2</sub>] associated with PRI regime. Conclusively, the modified BB-model was capable of predicting <italic>g</italic><sub>s</sub> and <italic>WUE</italic> of tomato leaves in various irrigation regimes at both <italic>a</italic>[CO<sub>2</sub>] and <italic>e</italic>[CO<sub>2</sub>] environments. This study could provide valuable information for better predicting plant <italic>WUE</italic> adapted to the future water-limited and CO<sub>2</sub> enriched environment.</p>