Tiffon-Terrade Benjamin

Abstract :

In viticulture, climate change is already affecting grape yield and quality through warming and changes in the hydrological cycle (Schultz, 2015). For example, increases in temperature have already resulted in accelerated ripening and notably earlier harvesting (Jones and Davis, 2000). In this context, the use of so-called 'dynamic agrivoltaic systems' (Valle et al., 2017) combining mobile photovoltaic panels (mounted on trackers) on top of agricultural crops within the same area could be beneficial. Since 2009, the company Sun'R in partnership with INRA has been developing such a Dynamic AgriVoltaics (DAV) project, the Sun'Agri project. The company itk, editor of decision support tools, is involved in the Sun'Agri 3 project. ITK's role is to coordinate the modelling activities and to develop these crop models for the optimisation of photovoltaic panel management strategies.

Within the framework of this project, thesis work (Valle et al., 2017, Elamri et al., 2018) has demonstrated the interest of this type of solution for high-value crops, such as market gardening. Indeed, the fluctuating shade induced by panels placed above the crop and whose orientation would be controlled according to the crop's needs could mitigate or even avoid the harmful effects of climate change by protecting crops, such as grapevines (Vitis vinifera L.), against high temperatures and strong radiation. However, solar radiation remains essential for the development of yields. It is therefore necessary to determine an "intelligent" control of the orientation of the panels that takes into account the variations in sensitivity to radiation for the different processes involved in the development of plant production and grape quality. Unfortunately, there is currently no data on the acclimatisation of vines under intermittent shading such as that created by solar panels, even if some knowledge exists for other types of artificial shading or shading related to the presence of neighbouring plants.

To this end, we propose a first line of research, targeting the functioning of the vegetative parts, which will consist of analysing and modelling the efficiency of radiation use (quantity of biomass formed per unit of radiation intercepted by the plant) under different shading regimes and at different stages of the plant's development. A second axis will be dedicated to the analysis and modelling of grape ripening kinetics under these same experimental conditions, taking into account the impact of the panels on the microclimate of the bunches and the use of radiation by the vegetative parts. These results will allow us to propose a global model integrating all these responses in order to analyse different shading situations and to identify dynamic shading practices that would be the most favourable in terms of yield and/or berry quality in an agrivoltaic system.

My thesis is based on a first experimental site with potted vines on the Montpellier SupAgro campus, and on a second experimental site in Piolenc with a vineyard in production under an agrivoltaic structure. The experiments will be conducted over two successive years to take into account possible cumulative effects. As the vine is generally cultivated under conditions of moderate hydric constraint at the end of the cycle, these conditions will be studied in combination with shading situations.