By Maggie Reiter, Graduate Research Assistant
Our worldwide water resources are declining at an alarming rate, both in quantity and quality. Because of this, legislation has been enacted to restrict our water use and the cost of water is increasing. In addition, global climate change assessments predict that our drought events will continue to increase in both frequency and magnitude. We must manage our turfgrass in a way that maintains performance and playability in order to cope with these trends of reduced water availability.
We have several field trials in Saint Paul evaluating turfgrass species and cultivars under acute drought. The trials are located under a rainout shelter (image 1). The rainout shelter is a state-of-the-art device that allows us to withhold precipitation and impose an experimentally controlled drought on the research area. Our shelter is an automated structure that will move to cover the test area during a rainfall event and remains off the area during fair weather. The entire apparatus can be moved with a signal from a control box onsite, a cellular text message, or a rain sensor located on top of the shelter.
Data is collected before, during, and after the 60-day drought period. Before the drought begins, the entire area is irrigated to uniformly wet the soil. For the next 60 days, the turf plots receive no water from irrigation or precipitation. After the drought, the area is irrigated with 1 inch of water per week and recovery data is collected for 45 days. Data collected through the entire experiment includes visual ratings of turfgrass quality, digital images for color analysis, and chlorophyll index readings to quantify plant tissue health. All plots are mowed at 2.75 inches.
Turf species have different responses to drought. Tall fescue is drought avoidant and can withstand the drought conditions well due to a deep root system. Fine fescues maintain adequate quality through the drought conditions because of an overall lower water requirement. The fine fescues have a small leaf area and slower growth rate, so the plant needs less water than other species. Kentucky bluegrass has a moderate drought tolerance. This grass turns brown and dormant but will recover with irrigation. Perennial ryegrass has a poor drought tolerance and usually dies under a 60-day drought period. Furthermore, there is some variation among cultivars within a turfgrass species.
Future research with our rainout shelter includes evaluating different management practices to withstand drought, looking at drought tolerance of other species and varieties, and assessing drought performance of shorter-cut turfgrass. Once we can identify the best grasses and management practices to endure acute drought, we can employ these systems to reduce our water use and foster a durable turfgrass stand.