Simulating 3D radiation transfer in kiwifruit orchards: A virtual laboratory for the horticulture industry
The photosynthesis process in plants transforms solar energy into chemical energy. Most of the radiation absorbed is used in this photochemical process, while a fracion of excess absorbed radiation is dissipated either as heat or re-emitted as flourescence. It has been shown that sun-induced fluorescence can probe the performance of the photosynthesis process, and thus it can be used to assess plant stress . However, a robust interpretation of the fluorescence signal requires both accounting for the biochemical conditions of plants and the radiative transfer of sunlight as it interacts with a complex 3D canopy structure. 
In this presentation, I introduce an ongoing project that aims to develop a rapid, non-invasive and robust simulation system to reveal signs of plant stress within kiwifruit orchards. This will be performed by using airborne hyperspectral imaging to detect the signal of sun-induced fluorescence emitted by the vegetative canopy. At the core of this novel capability lies a fully-fledged 3D radiative transfer and photosynthesis model of the canopy to perform a robust interpretation of the observed fluorescence signal. Multiple data sources that include proximal and LiDAR will be used to construct a 3D virtual orchard to account for the complex geometry of the orchards and their interaction with sunlight. As a result, this modelling system will deliver a spatial distribution of photosynthetic efficiency, plant stress in the orchards studied, and reveal likely sources of plant stress (e.g. imbalance of water, temperature or nutrient concentrations).
This project will support increased horticultural production and resilience, with reduced environmental impact, by developing a state-of-the-art, knowledge-based technology that delivers step-changes in crop yield and optimises orchard management. Although the study is focused on kiwifruit, the technology is expected to be adapted to other crops. This work is funded by MBIE’s Endeavour programme Smart Ideas 2021.
 Chlorophyll a fluorescence illuminates a path connecting plant molecular biology to Earth-system science, Porcar-Castell, 2021, Nature Plants, 7, 12, 2021
 O. Regaieg et al., "Simulation of Solar-Induced Chlorophyll Fluorescence from 3D Canopies with the Dart Model," IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020, pp. 4846-4849.
ABOUT THE AUTHOR
Alvaro Orsi is a Principal Research Scientist at PlantTech, with over 12 years of experience in Scientific computing, AI and Machine learning applied to address both scientific and data-driven industry challenges. In 2010 he obtained a PhD in Computational Cosmology from Durham University, UK, followed by postdoctoral fellowships in Chile and Spain. In 2015, he became a Cosmology Research Staff at Aragon's Research Centre of Physics of the Cosmos (CEFCA), in Spain. In 2019, shortly after moving to NZ he joined PlantTech as a Principal Scientist. Since then he has been implementing solutions for the NZ Horticulture industry through artificial intelligence technology.