Thermal bentgrass research promising

Photos Courtesy of Rutgers University.

Imagine a bentgrass that is perfectly adaptable to the deserts of Arizona, California and even Death Valley. Imagine greens that look fresh and healthy in summer temperatures of 110 degrees. Hard to imagine? Bingru Huang thinks it may be a possibility.

Thermal rough bentgrass, Agrostis scabra, was discovered by Huang among the thermal vents in Yellowstone National Park several years ago, and is now being examined by Huang’s group to unravel why the thermal bentgrass is able to tolerate extremely high soil temperatures. Knowledge of heat-tolerance mechanisms in the species could boost genetic enhancements of creeping bentgrass, Agrostis stolonifera. The goal is to produce a commercial fine-leaf grass that can do the job where heat and drought tolerance is needed.

Bingru Huang, turfgrass scientist at Rutgers University, shows off greenhouse specimens of a native, heat-tolerant bentgrass collected from the thermal vents of Yellowstone National Park.

Huang, a professor with a specialty in turfgrass physiology at Rutgers University, was reading an article in a scientific journal about an interesting wild grass at Yellowstone. That species held no possibilities for horticulture, but she thought there might be other species around the hot springs of Montana that would. She was right. After talking to national park officials eight years ago, asking in particular if there were any Agrostis species, she learned that there was indeed a native bentgrass that grew wild and flourished in areas of the geothermal park that had soils heated from underground vents.

In 2002, Huang traveled to Yellowstone and hiked 2 miles to the site with several scientists who wanted to make sure the site was protected, and measured soil temperatures. There, bentgrass was growing in isolated patches in the overheated soil.

“The soil temperature was around 40 degrees centigrade at 2 inches, and at 5 inches it was 50 to 60 degrees,” she says. The thermal rough bentgrass grew around inactive vents where the soil was heated from beneath by steam. She saw possibilities immediately. “I was very impressed. That was what I wanted … I was interested in why those species were able to grow actively in an area where other grasses die.”

That was in the month of July, when the bentgrass seedheads had already matured and dropped their seeds. The next spring, armed with a collecting permit, she returned in time to collect a few grams of seeds. Although the total amount of seed collected was small because of the restrictions on a relatively rare species (thermal Agrosta scabra is also found in a national park in California, but in smaller populations), she collected seeds in 2002, 2004 and 2005. She also undertook an ecological study of the species in the thermal areas, traveling back and forth from New Jersey, as well as hiring a part-time researcher to work in Yellowstone.

What she has found after growing the thermal rough bentgrass in the greenhouse and in small field plots at Rutgers is that the native is a “good quality” grass that will grow low to the ground like creeping bentgrass and has good leaf texture, yet is slow to reach its potential and will reach 5 inches in height if let go. According to a report written by Huang for the U.S. Golf Association, which is funding her research, the grass has less leaf senescence, higher photosynthesis activity and more efficient carbon utilization than creeping bentgrass. Most importantly, the thermal bentgrass is able to produce more roots and maintain greener grass canopy at temperatures that are detrimental to creeping bentgrass.

She is not looking at the species as a potential greens grass itself, however. She’s looking at it as breeding material. She foresees utilizing the genetic information learned from examining the thermal bentgrass to improve heat tolerance in creeping bentgrass through molecular marker-assisted breeding or genetic modification. The heat-tolerant genes in thermal bentgrass could be used as markers to detect heat tolerance levels in new cultivars of creeping bentgrass.

“We’ve already found genes to use in bioengineering, to improve creeping bentgrass,” Huang says. The native species is able to produce phytohormones such as cytokinins to maintain root growth and green leaves. Huang’s group, in collaboration with her colleague, Thomas Gianfagna, has transferred a gene from agrobacteria that controls cytokinin synthesis into creeping bentgrass to make improvements for better heat tolerance. They use Penncross, the old bentgrass standard, as a foundation for new genetic material for new experimental varieties. Tests are progressing on those bioengineered plant materials. This summer was the first year of their evaluation at the Rutgers farms, and it could be several years before Huang knows whether any of those breeding lines will be worthy of commercial release.

The native thermal bentgrass thrives where the soil is heated to up to 60 degrees centigrade. Growing in superheated soils along thermal vents in Yellowstone National Park, the native bentgrass has good genes.

Huang says that there also may be some potential for using plant growth regulators as a spray treatment on bentgrass or other grass types to increase heat tolerance in the future. Since cytokinins are already being used in commercial biostimulants, she is taking a closer look at the positive effects they have on bentgrass. It is proven that an increase in cytokinins and a reduction in ethylene production can help maintain leaf quality over time, and the discovery and study of thermal rough bentgrass has given validation for the possibility of using foliar or soil treatments to reduce heat stress and improve drought tolerance.

Huang’s work is not only promising for the future of bentgrass heat tolerance, it is also an illustration of the usefulness of native plant species in the development of commercial cultivars with direct application in horticultural uses.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.