Anthocyanin content and composition of Merlot grapes under temperature and late pruning conditions
One of the main aspects of Climate Change is the increase of temperatures during summer and grape maturity period. Physiological processes are influenced by these high temperatures and result in grapes with higher sugar concentration, less acidity and less anthocyanin content among other quality changes. One strategy to deal with the climate change effects is the implementation of late winter pruning to alter the effect of high temperatures during key periods by delays in maturity time.
A factorial trial was established in a Merlot vineyard of the Maipo Valley in Chile with three pruning times (traditional winter pruning, E-L stage 1; late pruning at bud burst, E-L stage 4; and late pruning at 2-4 cm shoot, E-L 9) and two temperature conditions (ambient or elevated), and three replicates per treatment. HPLC analysis were performed and anthocyanin content and composition were evaluated for each condition. Merlot grapes of any pruning and temperature condition had a predominance of Malvidin type anthocyanins, but total pigments were about 30% less in grapes grown under high temperatures, and most of the decrease was explained by less malvidin-3-glucosides. Late pruning slightly increased glucosilated anthocyanins when fruit maturity was reached under ambient conditions, but when temperature was increased about 1ºC with the OTC only late pruning at budbreak was beneficial, while late pruning at E-L 9 decreased anthocyanin content. Delphinidin and cyanidin glucosides were particularly affected by pruning time and temperature. Most acylated and coumaric forms showed only small changes, but total anthocyanins in a high temperature scenario were improved by a delay in pruning up to budbreak and reduced when pruning was with 2-4 cm shoots.
The results on fruit anthocyanins show the potential benefits of changes in pruning time as a tool to deal with the model temperature increase.
Acknowledgements: Fondecyt 11200703.
Issue: ICGWS 2023
1Instituto de Investigaciones Agropecuarias (INIA) La Platina, Santa Rosa 11610
2Instituto de Investigaciones Agropecuarias (INIA) Raihuén, Esperanza s/n, Estación Villa Alegre. Chile