Researchers in Spain aimed to study different field strategies to help growers adapt to hot and arid climate conditions. VSP-trained vineyard canopy orientation relative to the sun path can be manipulated by slope aspect orientation (site selection) and row direction choice. A third possibility of manipulation might be an angled VSP instead of an upright VSP. This was achieved by leaning a VSP-trained canopy in a field trial in Requena (Valencia). The effects on vine physiology, grape metabolism and quality were evaluated.
Project layout
The trial spanned two seasons and used Bobal as a red variety. Three different VSP systems were utilised in a north-south row direction: one planted upright (VSP), one with the canopy leaning 30º east (ESP) and the other with the canopy leaning 30º west (WSP). Considering that the canopy leaning affected radiation load and timing, the following measurements were taken: vegetative growth, vine water potential, canopy temperature, leaf area index, yield components, and must and wine composition.
Results
- Leaning affected vegetative growth, likely through measured differences in vine water status.
- Compared to VSP and ESP, WSP intercepted more light during morning hours, likely increasing photosynthetic activity and subsequent water use and reducing the vine water status and vigour without reducing yield.
- WSP also had the highest must total acidity, followed by VSP and ESP, most likely due to the reduced temperatures in the cluster zone of WSP treatment.
- WSP grapes also showed higher colour intensity, anthocyanins and total phenolics. These results also translated through to the wines.
- WSP wines also had higher esters and alcohol, contributing to a fruitier aroma.
Significance of the study
These results show that a canopy leaning towards the West can be a helpful practice in helping vines adapt to possible warmer conditions in future. This is achieved by intercepting more radiation during the morning while decreasing cluster temperatures in the afternoon. Although leaning a VSP canopy by 30 degrees would be considered impractical by most producers, this study emphasises the importance of effective canopy management and choosing the correct row direction to optimally intercept radiation and achieve cooler bunch microclimates during the hottest period of the day. These choices and practices directly influence grape quality.
Reference
Ferrer-Gallego, R., Buesa, I., García-Esparza, M. J., Álvarez, I., Intrigliolo, D. S., Ramírez-Cuesta, J. M., & Lizama, V. (2024). Effects of grapevine canopy leaning on grape composition and wine quality of ‘Bobal’. OENO One, 58(3). https://doi.org/10.20870/oeno-one.2024.58.3.8014
