Late winter pruning induces a maturity delay under temperature-increased conditions in cv. Merlot from Chile
Chile is considered vulnerable to climate change; and these phenomena affect several mechanisms in the grape physiology and quality. The global temperature increase affects sugar contents, organic acids, and phenolic compounds in grapes, producing an imbalance maturity. In this sense, an alternative to reduce the impact is to perform pruning after vine budburst, known as “Late Pruning” (LP).
The study aims are evaluating the LP, under ambient (Control) and temperature increase (T+) conditions, as agronomical technique that allows the imbalance of sugar and anthocyanins and delaying grapes maturation in cv. Merlot (Valle central, Chile) during two seasons. To achieve this goal tree pruning were made: winter pruning (WP); LP1 (Late pruning at budbreak) and LP2 (at shoots of 2-4 cm). The phenology of the crop was monitored and gas exchange, chlorophyll fluorescence and photosynthetic pigments were determined at key growth stages. At harvest (22±1 ºBrix), anthocyanins and total soluble solids were determined to evaluate the development of maturation.
During two seasons (21-22; 22-23) temperatures produced an earlier harvest in WP. LP1 treatments under control conditions had no effect on harvest date, and LP2 even advanced it. Under T+ conditions, LP1 had the most positive effects, delaying harvest by 5 to 22 days (season depending) and increasing total anthocyanin by 12% under ambient conditions and by 19% at T+. Regarding the effects on gas exchange, temperature significantly reduced photosynthesis in both seasons, but LP had no effect. In conclusion, the delay of sugar accumulation due to LP at budbreak could have a positive effect on anthocyanin concentration, without affecting other parameters such as photosynthesis.
Acknowledgements: This study is part of the project Fondecyt 11200703 (ANID). Thanks to Manuel Gutierrez for his field work and Jose Macias, graduate student.
Issue: ICGWS 2023
1Instituto de investigaciones agropecuarias, INIA La Platina.
2Undergraduate student. Facultad de Ciencias. Universidad de Chile.
3Instituto de investigaciones agropecuarias. INIA Raihuen.