By Jessica Till, University of Minnesota
Interactions between genotype and environment (G × E) are a major determinant of plant performance. Envirotyping is a way of characterizing the impacts of specific environmental conditions on plants. By documenting variations in temperature, precipitation, and soil properties, we aim to identify distinct patterns, or "envirotypes," likely to lead to winter damage (Table 1). Because winter damage poses a significant challenge to maintaining golf greens, understanding the complex interplay of environmental factors that contribute to this damage can help greenkeepers implement proactive measures to mitigate risks.
Table 1. Examples of environmental factors that may combine to impose winter plant stress.
| Season | Environmental conditions leading to winter damage |
|---|---|
| Fall | Warm temperatures combined with high soil moisture content resulting in insufficient cold hardening, followed by extreme low temperature exposure |
| Warm temperatures resulting in delayed soil freezing, followed by precipitation and low temperature events resulting in ice encasement | |
| Shaded environments associated with reduced light quality and/or intensity and altered microenvironment (e.g. high soil moisture, low soil temperature) | |
| Winter | Little or no snow cover, along with prolonged low soil moisture and extreme low temperature exposure, resulting in desiccation and/or direct low-temperature kill |
| Freeze-thaw events with high moisture availability, followed by extreme low temperature exposure, resulting in ice development and intracellular freezing | |
| Winter precipitation events resulting in prolonged ice encasement, and subsequent anoxia and fermentation metabolism | |
| Spring | Ice melt, followed by re-exposure to ambient air/light/temperature conditions and exposure to fermentation toxins in soil |
| Warm temperatures leading to deacclimation (e.g. water uptake, regrowth), followed by below-freezing temperatures |
Early envirotyping efforts by our group revealed that weather data alone was not able to capture the variables most closely associated with winter damage. This highlighted the importance of characterizing the soil environment that represents conditions experienced by the grass crown, together with the aboveground environment. With the help of golf course superintendents, the WinterTurf project team at the University of Minnesota has been monitoring environmental conditions on golf greens across North America and parts of Europe using a network of custom-designed sensor nodes. We are leveraging the in-situ sensor data to determine the various combinations of soil properties and weather conditions associated with turfgrass damage.
Since 2021, the sensor nodes have been continuously recording data during the cold season, including air and soil temperature, light intensity, soil moisture, and soil gas concentrations. Superintendents have been instrumental in providing additional information about their management practices and documenting snow and ice cover on their greens. Using unsupervised machine learning techniques such as time-series clustering analysis, some trends are starting to emerge. For example, the soil temperature data in Figure 1 show broad groupings that occurred over the winter of 2021-2022. Certain sites experienced a fairly sudden transition from warm to near-freezing soil temperatures (Cluster 1); this is expected to leave turf vulnerable to winter damage as it may not allow adequate time for cold acclimation.
Work is ongoing work to find the relationships between the variety of environmental parameters measured by the sensor nodes and how they are connected to the probability of turfgrass loss. As we continue to collect data over additional winters, we will also gain a better picture of the variability in environmental patterns from year to year on a given green to assess the dynamic nature of winter stress. Course superintendents have also contributed data on historical winter damage to their greens, which will allow us to supplement our in-situ data with remotely sensed environmental data from past years.
The insights gained from this envirotyping work are expected to extend beyond golf course management to other grass-based systems, such as parks, sports fields, and residential lawns. It also offers a framework for understanding winter damage in various biennial and perennial cropping systems that face challenges in cold-climate areas, including orchards, vineyards, and winter grains. Our hope is that identifying envirotypes of turfgrass survival or loss can help researchers decipher the nuanced environmental conditions that influence winter stress on a wide range of managed vegetation systems.