Shading enhanced microclimate variability, photomorphogenesis and yield components in a grapevine agrivoltaic system in semi-arid Mediterranean conditions in Puglia region, southeastern Italy

• Photovoltaic panels affected vineyard microclimate. • Altered light spectrum beneath panels enhanced photomorphogenic processes. • Agrivoltaic grapevines exhibited higher yields compared to full sun vines. • Agrivoltaic systems can be a sustainable approach in arid and semi-arid regions. Agrivoltaics (AV) emerged for its dual land use function as renewable energy source of strategic importance to the global low-carbon transition, climate resilient system and food crops production. A two-year study on grapevines grown under photovoltaic panels was conducted in Puglia region, southeastern Italy, focusing on microclimatic modifications, physiological responses, and yield performance under varying shading conditions. comparing full sun (FS) to either low shade (LS) or high shade (HS) vine treatments under AV. Quantitative analyses revealed spatial and temporal variability in the microclimatic conditions for the vines. In the HS position, soil moisture was 16% higher compared to the FS treatment, while soil temperatures were moderately stabilized. Wind parameter modifications between day and night also influenced relative humidity and air temperature, with a strong night cooling effect of up to 3.5 °C. Furthermore, high diffusive radiation fraction and an altered spectrum profile in wavelength peaks intercepted within the AV canopy enhanced photomorphogenic processes such as increased stem length, leaf expansion and chlorophyll index, while also shade improved midday water status and maximum photosystem II activity. Considerable variations on stomatal conductance were revealed on daily basis in response to the vapour pressure deficit (VPD) gradient, blue to green and blue to far-red ratios, especially in LS leaves by up to 30% increase. Regarding productivity, the LS achieved optimal cluster weight (1.15 kg/vine) and anthocyanin content (15.27 mg/g), although HS reduced sugar accumulation to 19.1°Brix compared to 26.3°Brix in FS conditions. These findings underscore that tailored applications that include site-specific designs to local microclimatic conditions and respecting crop-specific layout criteria, reverse the negative effects of shading sensitivity while ensuring beneficial impacts on grapevine growth, optimizing crop yield, and maintaining sufficient energy output even with low-input technological solution.