Sundial Vineyard

Introduction

The Sundial Vineyard project in Puente Alto appellation, Chile is a 5-season experiment aiming to determine how sun exposure influences grape quality and yield. The experiment is a combined effort between the Centro de Investigación e Innovación and the award winning wine company Viña Don Melchor. The winery, already known for their quality, has the goal to continue improving and refining grapevine cultivation.

Plant orientation significantly alters incoming radiation, strongly affecting cluster-zone microclimate. Similarly, the proximity of grape rows impacts grape growth. Vines adapt by modifying leaf size, chlorophyll concentration, leaf angle, and overall canopy structure—all of which change how much light reaches the clusters. These changes influence chemical composition, sunburn incidence, and other quality‑related traits.

In this project, the researchers are evaluating how over 60 plant traits are impacted by sun exposure, which includes studying the cluster orientation, radiation intensity, exposure duration, time of day, and the resulting temperature reached by the clusters. The data from this project is being used to characterize cluster microclimate, physiological traits, yield, sunburn incidence, and berry dehydration. They are also conducting an in‑depth analysis of grape chemical composition, including phenolics and aroma compounds. This study spans several years to yield a large sample size of data and account for natural climate variability between years.

Setup and Sensors

Orientation and density are crucial in this experiment, and the design cleverly controls both variables. 900 Cabernet Sauvignon plants have been planted radially in 60 rows. Each row is spaced 50 cm apart in the middle and 200 cm apart around the perimeter (an angle difference of 6 degrees for each row). These are planted on ungrafted rootstock over an area of 0.16 hectares.

Temperature–radiation relationships depend heavily on the time of day at which exposure occurs and the variable levels reaching the different parts of the plant, so radiation was measured directly from the plant level in this experiment, rather than trying to model it. A UV sensor was installed in the direct sun as a reference. Ten PAR bars were installed throughout the vineyard canopy with ten infrared thermometers. These instruments record measurements every five minutes using a Campbell Scientific datalogger to collect daily curves of cluster temperature and radiation in the cluster zone. Spot measurements around the vineyard are taken using infrared radiometers and PAR bars, either as portable handheld units or connected to microcaches for mobile viewing and data logging.

Chlorophyll concentration is influenced by several factors, including plant water status, which is also affected by orientation, total light exposure, and the timing of that exposure. These, in turn, impact yield and photosynthetic capacity. The Chlorophyll Concentration Meter allows the team to nondestructively and quickly take measurements across plants in the vineyard.

Conclusion

As of February 2026, the Sundial Vineyard project is in its third year, and will continue for more seasons in order to strengthen statistical confidence and account for interannual climate variability. However, clear and repeatable trends are emerging. Read the abstract here for the preliminary results shared by Sebastián Vargas MSc & PhD, R&D&I leader in viticulture and oenology at the Centro de Investigación e Innovación.
Vine orientation and planting density are demonstrably influencing yields per hectare, water use, solar radiation, photosynthesis, temperature at the cluster level, the production of phenolic compounds, and more parameters. See below the illustrations of chlorophyll concentration, PPF, and temperature in the cluster zone.

By combining continuous radiation and temperature monitoring with detailed physiological and compositional measurements, this team is building a high-resolution understanding of how microclimate shapes grape quality. As the study progresses, these findings are expected to provide practical guidance for optimizing vineyard orientation and canopy management strategies to increase yield consistency, fruit quality, and improve resource efficiency.

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