Comparing Microclimate Conditions Induced by Semi-Transparent and Conventional Agrivoltaic Systems and Their Effects on Arugula Response (Eruca vesicaria) in Southern Italy

Agrivoltaic Systems (AV) constitute a viable alternative to mitigate land-use competition by enabling the simultaneous production of agricultural crops and solar photovoltaic energy. However, the heterogeneous shading and microclimatic modifications induced by AV systems can alter solar radiation, crop physiological performance, and, consequently, its biomass. This study evaluated the effects of two static ground-mounted AV systems—semi-transparent (ST) and conventional opaque (CON) panels—on the growth, physiology, soil water variations, and yield of Arugula (Eruca vesicaria) cultivated in southern Italy from August to October 2022; compared with an open-field control (REF). Daily soil temperature and water content were monitored, alongside leaf-level gas exchange measurements at three vegetative stages. Global solar radiation was reduced by 70% under ST and 80% under CON, reducing Photosynthetically Active Radiation (PAR), transpiration, and net photosynthesis, while leaf water use efficiency remained comparable to REF. Sequential harvests showed that although yields were consistently highest in REF, ST 50% and CON 50% exhibited partial recovery in fresh and dry biomass by the third cutting, reflecting the mitigating effect of seasonal temperature declines on shading. Notably, soil water uniformity improved under AV systems, reaching 90% under ST and 94% under CON compared with 85% in REF, due to reduced evaporative losses and enhanced lateral soil water redistribution. Overall, while AV-induced shading limits radiation and yield in short-cycle leafy arugula, microclimate modulation under AV systems can enhance soil water distribution and partially buffer growth under less favorable seasonal conditions. These findings highlight the trade-offs between crop productivity and resource-use efficiency in AV systems and emphasize the importance of tailoring their design to crop type and local climatic conditions, providing valuable guidance for future experimental research and for policymakers aiming to support sustainable agrivoltaic deployment.