Foliar application of nettle and Japanese knotweed extracts on Vitis vinifera : impact on phenylpropanoid biosynthesis and antioxidant activity during veraison and harvest of cv. Touriga Franca

Foliar applications of nettle (Urtica spp.) and Japanese knotweed (Reynoutria japonica) extracts significantly enhanced bioactive compound content and antioxidant activity in Touriga Franca grapevines, a key variety in the Alto Douro Wine Region. Nettle extract increased total carotenoids in leaves and boosted phenolic content along with ferric reducing antioxidant power (FRAP) in berries, while Japanese knotweed extract elevated flavonoid levels in leaves and DPPH antioxidant activity in berries. Conducted over two growing seasons (2019–2020), the study demonstrates that these plant-based extracts can stimulate phenylpropanoid biosynthesis, improving grapevine physiological performance and berry quality—offering a sustainable approach to enhance wine quality without synthetic interventions.

Monteiro, E., Baltazar, M., Pereira, S., Correia, S., Ferreira, H., Bragança, R., Cortez, I., Castro, I., & Gonçalves, B. (2024). Foliar application of nettle and Japanese knotweed extracts on Vitis vinifera: impact on phenylpropanoid biosynthesis and antioxidant activity during veraison and harvest of cv. Touriga Franca. Journal of the Science of Food and Agriculture, 104(7), 4260–4267. Portico. https://doi.org/10.1002/jsfa.13310