This study aimed to determine whether in-canopy misters could provide effective cooling in vineyards in order to mitigate the negative effects of heatwaves.
To address the challenge, the study was conducted in the Riverland and Adelaide regions in Australia on Sauvignon blanc and Cabernet Sauvignon. The study lasted two seasons, namely 2016-2017 and 2017-2018. Grapevine canopies were cooled using the following water-based, evaporative treatments:
- Fine mist application in the canopy (ICM) when temperatures exceeded 35 °C
- Under canopy sprinklers (UCS) during warm nights preceding heatwaves
- Supplemental drip irrigation (SI) during warm nights preceding heatwaves
In all treatments, canopy temperatures were 5°C cooler than ambient temperature.
- During heatwaves, the SI treatment with additional irrigation maintained under vine temperatures of 2°C lower than the control while midrow temperatures were 7°C lower than the control.
- In most treatments, cooling resulted in improved vine water status, physiological performance and yield – especially in the UCS treatment on Sauvignon blanc in Riverland.
- SI and UCS vines consistently had superior water status and gas exchange than controls, and maintained these levels despite prevailing environmental conditions.
- SI vines had the highest yield and crop load in both seasons.
- Differences between treatments were not as evident in the Cabernet Sauvignon in Adelaide.
- Riverland fruit under misting had higher levels of volatiles but lower wine polyphenols than controls.
- UCS and SI treatments had higher juice and wine acidity.
Significance of the study:
In Southern Australia, heatwaves are becoming more prevalent and last longer too. This study suggest some solutions for mitigating heat stress in vineyards following heatwaves. Some of these methods will however be difficult to implement where water sources are limited or in dryland areas. Installing a mister system in a vineyard also has cost implications.
Photo: (misters) Source: https://www.wineaustralia.com/news/articles/stay-cool-over-summer?utm_source=Wine+Australia+RD%26E+News&utm_campaign=b8ba7ea8f6-RD_E_News_December_2018&utm_medium=email&utm_term=0_440931c1c7-b8ba7ea8f6-210375317