Impact of temperature extremes on the phenology of grapevine varieties

Abstract

Aim: A growing number of studies call attention to the consequences of climate change on agriculture, including impacts of climate extremes such as drought, heat weaves and frost. The aim of this study was to quantify the influence of temperature extremes on various phenological events of grapevine varieties in south west Switzerland (Leytron, Canton of Valais). We aim to capture the occurrence of extreme events in specific years, grapevine varieties, and phenological phases to rank the varieties based on their sensitivity to temperature extremes and thus quantify their robustness. Methods and results: Phenological observations (1978 – 2018) for six varieties of Vitis vinifera ('Arvine', 'Chardonnay', 'Chasselas', 'Gamay', 'Pinot Noir', 'Syrah') were studied using event coincidence analysis. Extreme events were defined as values in the uppermost/lowermost percentiles of the distributions of the variables under study. The results showed that significantly more extreme temperature- and extreme phenological events occurred in Leytron between 2003 and 2017 than in earlier years. It was also found that the occurrence rate of extreme events was independent of the growth stage (between 13-19%). Based on the total number of extreme events the varieties do not differ in their response to temperature extremes. Conclusion: The event coincidence analysis is an appropriate tool to quantify the occurrence of extreme events. The occurrence of extremes temperature events on various grapevines had a clear effect in advancing the timing of phenological events. However, there was no varietal difference in the response of varieties to extreme temperature events, thus more research is needed to outline the best adaptation measures. These findings are remarkable in the era of climate change, when extreme climate events are predicted to occur more frequently. Significance of the study: Information on climate impacts is enabling appropriate adaptation responses and is supported with knowledge on how the different varieties are affected under extreme conditions. Our findings are important for Swiss winemakers when making decisions on vineyard management in the future.

Keywords

• phenological sensitivity, temperature stress, occurrence, Switzerland, event coincidence analysis