CRootBox: A structural-functional

11 ● Background and Aims 12 Root architecture development determines the sites in soil where roots provide input of carbon 13 and take up water and solutes. However, root architecture is difficult to determine 14 experimentally when grown in opaque soil. Thus, root architectural models have been widely 15 used and been further developed into functional-structural models that simulate the fate of water 16 and solutes in the soil-root system. We present a root architectural model, CRootBox, as a 17 flexible framework to model architecture and its interactions with static and dynamic soil 18 environments. 19 ● Methods 20 CRootBox is a C++ -based root architecture model with Python binding, so that CRootBox can 21 be included via a shared library into any Python code. Output formats include VTP, DGF, RSML 22 and CSV. We further created a database of published root architectural parameters. The 23 capabilities of CRootBox for the unconfined growth of single root systems, as well as the 24 different parameter sets, are highlighted into a freely available web application. 25 ● Key results 26 We demonstrate the use of CRootBox for 5 different cases (1) free growth of individual root 27 systems (2) growth of root systems in containers as a way to mimic experimental setups, (3), 28 field scale simulation, (4) root growth as affected by heterogeneous, static soil conditions, and 29 (5) coupling CRootBox with Soil Physics with Python code to dynamically compute water flow in 30 soil, root water uptake, and water flow inside roots. 31 ● Conclusions 32 In conclusion, we present a fast and flexible functional-structural root model which is based on 33 state-of-the-art computational science methods. Its aim is to facilitate modelling of root 34 responses to environmental conditions as well as the impact of root on soil. In the future, we 35 plan to extend this approach to the aboveground part of the plant. 36 . CC-BY 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/139980 doi: bioRxiv preprint first posted online May. 19, 2017;