https://hdl.handle.net/10012/21444

Climate change is impacting wine-growing regions globally, with varying effects on vineyards. While some regions may benefit from warmer temperatures, others may face detrimental consequences, especially with the predicted increase in extreme weather events or less than optimal conditions. Precision viticulture uses remote and proximal sensing technologies to monitor these changes and adapt vineyards by providing insights into vine health and grape maturity. This information can be used to determine when intervention is needed in vineyards to maintain grape quality. However, existing precision viticulture methods are limited, such as the inability to provide continuous, real-time data and the utilization of reflected light, which can lead to inaccurate measurements. Current research has not yet investigated the potential of using transmitted light for monitoring vine health and grape maturity, a method that could provide more accurate insights. This thesis seeks to fill this gap by evaluating the feasibility of applying a novel system, TreeTalker-Wine© (TTW), to continuously monitor grapevine health and maturity through transmitted light in commercial vineyards.
To test the application of TTWs for monitoring vine health, the sensors were deployed under the canopy of Cabernet Franc in two commercial vineyards in Niagara, Ontario, Canada. Spectral data collected by the TTWs was used to calculate the daily Normalized Difference Vegetation Index (NDVIT) based on transmitted light. The resulting NDVIT values were consistent with expected ranges and aligned with viticultural management practices and weather events. To assess the potential of TTWs for monitoring grape maturity, partial least squares (PLS) models were developed for Cabernet Franc, Chardonnay, and Riesling varieties using spectral data from the grape clusters, along with air temperature and Total Soluble Solids (TSS) content. Grape clusters were collected bi-weekly from a third vineyard in Niagara, Ontario, Canada, starting at the pea-size stage and continuing through veraison. After veraison, sampling frequency increased to weekly until harvest. After each collection day, the fruit was transported to a laboratory with a plant growth chamber designed to replicate the vineyard’s environmental conditions. Grape clusters were suspended over the TTWs in the plant growth chamber to collect spectral signatures of the fruit before the entire cluster was juiced to determine TSS content. The results of the PLS models suggest that TTWs are able to determine TSS content from the spectral signatures of the grape clusters, however unique models are required for each grape variety. These findings indicate that TTWs offer a promising approach to precision viticulture. Future research is needed to assess a broader range of grape varieties to better understand the relationship between NDVIT and vine health, as well as to refine the TSS prediction models. This will enable further exploration of the potential of transmitted light in monitoring grapevine health and maturity, supporting more accurate and timely viticulture practices in changing climate.

https://hdl.handle.net/10012/21444