Wheat Functional Traits and Photosynthetic Responses to Dynamic Shading in Agrivoltaic Systems

The growing demand for food and renewable energy has stimulated interest in agrivoltaic systems, yet their effects on crop physiology remain poorly understood. This study investigates how dynamic shading from high biaxial solar trackers influences wheat photosynthesis and functional traits. Across 2 years and eight field sites in western France, nine leaf-level traits related to carbon and nitrogen economy, together with plant height and plant density, were measured at anthesis and analysed against 14 environmental and management variables. Received radiation (RR) was the dominant driver of physiological responses, significantly reducing CO₂ assimilation (A_sat, A_max), respiration, and photosynthetic nitrogen use efficiency (PNUE), while changes in air temperature, soil temperature, and relative humidity remained limited under the elevated agrivoltaic system. Contrary to expectations, wheat exhibited no major morphological acclimations and only limited physiological adjustment to shade. Specific leaf area (SLA) remained unchanged, as did the light compensation point (LCP). The only consistent response was an increase in chlorophyll content, associated with higher leaf nitrogen concentration, which was nevertheless insufficient to maintain photosynthetic rates at levels observed under full light. These findings demonstrate that wheat shows limited structural plasticity to intermittent and heterogeneous shading, highlighting the specificity of elevated, mobile agrivoltaic systems compared with low, ground-mounted photovoltaic installations. We conclude that varietal selection for agrivoltaics should prioritize traits enhancing photosynthetic induction and nitrogen efficiency under fluctuating light conditions.