Agrivoltaics in Mediterranean viticulture: Impacts on physiology, yield andm biodiversity

Agrivoltaic (AV) systems are emerging as a dual land-use strategy to mitigate climate stress in Mediterranean viticulture, yet cultivar-specific responses remain insufficiently quantified. This study evaluated the effects of photovoltaic-induced shading on Vitis vinifera L. cv. Primitivo during the 2024 growing season in southern Italy under full sun (FS) and beneath the AV system with two light conditions, low shade (LS), and high shade (HS) within a rainfed management of the vineyard. Shading modified the microclimate, reducing air temperature by approximately 0.5–1 °C and increasing relative humidity by 2–14%. Marked morphological responses were observed, with shoot length increasing from 115.8 cm (FS) to 267.20 cm (LS) and 274.2 cm (HS), alongside higher leaf area and biomass under shaded conditions. Stomatal density increased from 208 stomata mm⁻² (FS) to 288–308 stomata mm⁻² (LS–HS), and stomatal size was also higher under HS. Physiological responses were treatment-dependent: net CO₂ assimilation showed variable patterns, whereas midday stem water potential was higher (less negative) under HS compared to FS, indicating improved plant water status. Chlorophyll content (SPAD) increased under shading. Grapes beneath the panels showed increased yield from 0.41 kg/cane under FS to 1.36 kg/cane under LS and 1.06 kg/cane under HS; titratable acidity decreased from 7.29 g/L (FS) to 6.51 g/L (LS) and 6.09 g/L (HS), while berry soluble solids were reduced both in HS (22.9 °Bx) and LS (24.4 °Bx) with respect to FS (25.8 °Bx). The two floristic surveys carried out during the season (spring and fall) clearly indicated a higher spontaneous plant diversity under AV conditions. Overall, AV shading under Mediterranean conditions was associated with changes in grapevine morphology, physiology, and yield. This research specifically demonstrated that PV shading alters the micro-morphology of grapevines by increasing stomatal density and size to optimize gas exchange under reduced light. Furthermore, it uniquely demonstrates that the modified microclimate actively favours the biodiversity of spontaneous flora between the vines, showing that agrivoltaics in Mediterranean climate viticulture can restore local ecological ecosystems rather than just maintaining crop production.