Impact of summer green pruning on the phenolic content of grapes from Cabernet Franc cultivar

Ferihan Emurlova, Tatyana Yoncheva

Abstract: A study was carried out on the phenolic content of Cabernet Franc grape cultivar depending on the applied summer green pruning operations. The research was conducted in a fruiting plantation and covered two consecutive harvests (2021–2022). The effects of bunch thinning and a combination of thinning and defoliation in the bunch area on total, flavonoid, non-flavonoid phenolic compounds and anthocyanin content in rachis, seeds, skins and berries were investigated. The change of the climate factors, air temperature, amount of precipitation and relative air humidity during the vegetation period of 2021 and 2022 was monitored. A positive impact of the applied pruning practices on the phenolic content of grapes compared to the control was found. The amount of the investigated phenolic components in the set variants increased in the order: without green pruning (control) ˂ bunch thinning and defoliation ˂ bunch thinning, and in the structural elements of the grape berries < skins < rachis
< seeds. Grapes from the 2022 harvest had a better phenolic content, because of more favorable weather conditions during the ripening period, affecting the accumulation of phenolic compounds.

Keywords: Cabernet Franc; climate factors; grapes; phenol content; summer green pruning

Date published: 2023-08-21