Biochemical trade-offs in basil: Photovoltaic shading and alcoholic foliar sprays in a climate-smart greenhouse.

This study evaluated the effects of photovoltaic (PV)-induced shading and alcoholic foliar application on photosynthetic pigments, biochemical characteristics, oxidative stress, and essential oil composition of Italian basil (Ocimum basilicum L.) grown under greenhouse conditions during two cultivation seasons. Three PV roof coverage levels, 0% (C0), 50% (C50), and 100% (C100), were combined with ethanol-methanol foliar spray treatments at different ratios. Moderate shading (C50) sustained most biochemical traits without significant decline while directing favorable shifts in essential oil composition, notably enhancing the accumulation of eucalyptol and linalool. In contrast, full roof coverage (C100) significantly increased chlorophyll a, chlorophyll b, and total chlorophyll contents by 29%, 27.5%, and 34%, respectively, indicating physiological acclimation to reduced irradiance, but reduced total phenolic content, flavonoids, and antioxidant activity by 51%, 25%, and 28%, respectively. Plants grown under full-light conditions exhibited significantly greater malondialdehyde accumulation, with MDA levels 19.7% and 28.3% higher than shaded treatments across the two cultivation seasons, reflecting increased oxidative stress. Alcoholic foliar application reduced lipid peroxidation and improved biochemical performance, with the 30% ethanol +30% methanol treatment producing the strongest response. Alcohol treatments also modified the volatile composition through increased neophytadiene abundance. The results indicate that moderate PV-induced shading, particularly at 50% roof coverage, combined with optimized alcoholic foliar application, can improve physiological performance and favorably modulate phytochemical composition in greenhouse-grown basil.