Combining field experiments under an agrivoltaic system and a kinetic fruit model to understand the impact of shading on apple carbohydrate metabolism and quality

Abstract

Shading with dynamic agrivoltaic (AV) could be a solution to mitigate the effects of climate change but their impact on the fruit quality has not been reported. Apple metabolism and quality were evaluated in a dynamic AV system in a mature ‘Golden Delicious’ orchard in the south of France (2019–2021). Trees were exposed to three different light treatments: maximal shading all day ‘AV max’, morning shading ‘AV morning’, and afternoon shading ‘AV afternoon’. Results were compared with control trees ‘C’. Shading did not modify fruit maturity and therefore harvest date. AV max reduced dry matter content (24%), soluble carbohydrate concentrations (23%) but maintained malic acid concentrations for 2 years out of 3. Sugar:acid ratio was significantly reduced under AV max. The kinetic model simulated the concentrations of soluble sugars, starch, and other compounds (organic acids, cell walls, proteins) and their interactions with reaction rates driven by multiple parameters. The calibration of these parameters with the experimental data made it possible to simulate carbohydrate dynamics of the different experimental years and treatments with a common set of parameters. This common set of parameters indicated that shading did not mostly alter apple metabolism. The model indicated that shading reduced incoming carbon flows and increased water entering the fruit, being the main reason of internal quality modifications. Shading with AV systems seems a useful tool to modify fruit quality for future higher temperatures. Dynamic AV offers the opportunity to tilt the solar panels for optimising carbon acquisition in critical periods for quality determination.