If you’re a frequent reader of this blog, you are probably familiar with the idea of applying water deficit to vines. Sap Flow, our longest standing product on the market, builds on the very idea that if done right, regulated water deficit can improve fruit quality and preserve yield while using less water. To improve quality of insights delivered to our customers through Sap Flow, the Fruition Sciences team is always following the latest research on impacts of regulated water deficit on berry composition, development and quality.
Water deficit and berry color
Professor Castellarin of University of British Columbia, who spoke at last year’s Vintage Report in Napa, recently published an interesting paper on deficit irrigation and berry color change for Merlot grapes. As in most deficit irrigation studies, the study authors compared vine outcomes under a deficit scenario with those under a control scenario (control means standard commercial practice). The deficit scenario involves withholding irrigation between 25 and 31 days after anthesis.
For this study, the outcome of interest is when berry clusters start and finish changing color from green to pink, blue or red. Using visual estimation, the authors recorded the day the first berry in a cluster changed color and the percentage of red berries that had changed colors every five days until the color change was complete for the whole cluster.
The authors found that berries under regulated deficit irrigation began changing color around the same time as under the control scenario. However, deficit irrigation accelerated the color change process. The berries under deficit completed color change from green to red 7, 3 and 6 days before the control scenario in 2011, 2012 and 2013 respectively. What could explain this acceleration of color change? The authors did not provide a definite answer, but suggested that more work could be done to explore possible roles of anthocyanin accumulation and abscisic acid hormone concentration at veraison in regulating color change.
Water deficit, yield and fruit quality
Fruition Sciences tested deficit irrigation with the aid of Sap Flow using a grant from the Water Metropolitan District of Southern California in 2014-2015. We found that in all six participating wineries, yield and sugar accumulation were not negatively affected by deficit irrigation. Meanwhile fruit quality is preferred in the deficit scenario. In a 2015 study by Herrera et al., the authors also found that deficit irrigation improve wine’s desirable attributes and boost anthocyanin accumulation.
It’s key to understand that results of deficit irrigation experiments can vary depending on climate conditions, design of the irrigation treatment and other vineyard management practices. We encourage you to check out Professor Castellarin’s talk at the 2015 Vintage Report in Napa. The talk provides a wider perspective into a range of water deficit experiments and their impacts on grape physiology.
Learn more about our product Sap Flow, which helps winemakers enhance fruit and wine quality while saving significant amounts of water. Or you can connect with us at our upcoming Vintage Report conference in Napa in January 2017. Check it out at https://www.vintagereport.com/en/napa-2016.