HydroShoot: a functional-structural plant model for simulating hydraulic structure, gas and energy exchange dynamics of complex plant canopies under water deficit—application to grapevine (Vitis vinifera)

R Albasha,C Fournier,M Chelle,J A Prieto,T Simonneau,C Pradal,E Lebon,G Louarn

doi:10.1093/insilicoplants/diz007

Abstract

AbstractThis paper presents HydroShoot, a leaf-based functional-structural plant model (FSPM) that simulates gas exchange rates of complex plant canopies under water deficit conditions. HydroShoot is built assuming that simulating both the hydraulic structure of the shoot together with the energy budget of individual leaves is the asset for successfully scaling-up leaf to canopy gas exchange rates. HydroShoot includes three interacting modules: hydraulic, which calculates the distribution of xylem water potential across shoot hydraulic segments; energy, which calculates the complete energy budget of individual leaves; and exchange, which calculates net carbon assimilation and transpiration rates of individual leaves. HydroShoot was evaluated on virtual and real grapevines having strongly contrasted canopies, under well-watered and water deficit conditions. It captured accurately the impact of canopy architecture and soil water status on plant-scale gas exchange rates and leaf-scale temperature and water potential. Both shoot hydraulic structure and leaf energy budget simulations were, as postulated, required to adequately scaling-up leaf to canopy gas exchange rates. Notwithstanding, simulating shoot hydraulic structure was found more necessary to adequately performing this scaling task than simulating leaf energy budget. That is, the intra-canopy variability of leaf water potential was a better predictor of the reduction of whole plant gas exchange rates under water deficit than the intra-canopy variability of leaf temperature. We conclude that simulating the shoot hydraulic structure is a prerequisite if FSPMs are to be used to assess gas exchange rates of complex plant canopies as those of grapevines. Finally, HydroShoot is available through the OpenAlea platform (https://github.com/openalea/hydroshoot) as a set of reusable modules.

Highlights

Climate change is seriously challenging viticulture sustainability in its current areas of production (Hannah et al, 2013; van Leeuwen et al, 2013; Duchêne et al, 2014)
This first illustrative example on virtual canopies shows that the effect of canopy architecture on its gas-exchange and temperature behaviour is captured in HydroShoot
We presented in this paper the functional-structural plant model (FSPM) HydroShoot

Summary

Introduction

Climate change is seriously challenging viticulture sustainability in its current areas of production (Hannah et al, 2013; van Leeuwen et al, 2013; Duchêne et al, 2014). C FSPMs received little attention in grapevine scientific literature to assess the s impact of shoot architecture on plant gas-exchange rates (Medrano et al, 2015 a). This is probably u due to the inherent complexity in scaling up eco-physiological processes from the leaf to the canopy n level, as strong variability in gas exchange rates (CO2 versus water vapor) exists inside the canopy driven by variations in micrometeorological conditions and leaf functional traits This scaling-up task is even more complex under water deficit conditions, as stomatal aperture is likely to reduce under water deficit in a non-uniform pattern across the canopy

Methods

Results

Conclusion