Nine-Year, Multi-University Effort Develops Drought Tolerant Turfgrasses

Associate Professor Susana Milla-Lewis and graduate students inspect turfgrass plots. Photo by NC State University.


Water conservation is an increasing issue and turfgrass has deservedly gotten a bad rap as a thirsty consumer of this precious resource. (The typical suburban homeowner irrigates an estimated 10,000 gallons of water each year, primarily aimed at their lawn). While xeriscaping and turfgrass alternatives make sense in some applications, turf also provides substantial environmental and economic benefits in our landscape. It mitigates heat around homes, stabilizes soil against erosion, provides safe play space, and reduces noise, glare, and pollution. Eliminating turf would create a whole new set of environmental challenges.

To help mitigate turf’s impact on water use, a team of 32 turfgrass researchers from six major universities, including North Carolina State University, has collaborated over the past nine years to produce drought tolerant warm-season turfgrasses. Recently, a specialty crops grant from the National Institute of Food and Agriculture was approved to continue the multi-university group’s works. (Texas A&M, University of Florida, University of Georgia, and Oklahoma State University have been members of the team since 2010. University of California – Riverside was added to the team for this new project.)

New Phase Of Study

NC State’s Susana Milla-Lewis, an associate professor and University faculty scholar, will be at the helm in the new phase of study. “Our 2010 and 2015 projects were crucial in the development of drought-tolerant turfgrass cultivars. The levels of improvement of these grasses are promising and validate the need to promote adoption, continue cultivar research, and develop tools that facilitate the breeding process,” Milla-Lewis said.

The team has focused on selecting and testing drought-tolerant cultivars of four of the most economically important warm-season turfgrass species in the southern US. By exchanging plant materials and data among university breeders, turf varieties are tested under many climatic conditions, and results accumulate quickly.

“The collaboration among breeders across such different environments is priceless,” Milla-Lewis said. “It helps us select better lines with more performance stability because they have been tested against a wide range of weather conditions like drought and cold as well as an array of pests and diseases.”turfgrasses

The team has already released six new drought-tolerant varieties from previous project phases including:

  • Two bermudagrasses called TifTuf and Tahoma 31;
  • Two St. Augustine grasses called TamStar and CitraBlue; and
  • Two forthcoming zoysiagrass varieties.

TifTuf, a University of Georgia release, alone has achieved massive success. The team’s research demonstrated a 40% water savings over the leading bermudagrass, without loss of turf quality. This convincing research data has led to the rapid acceptance of TifTuf within the sod industry, representing a six-fold return in gross earnings compared to the grant investment.

Landscapers can purchase these grasses here:

With tangible success already, what will the next research phase include? More trials with new avenues to share and test. Plant breeding is a long-range game, 10 to 15 years in most cases. While, the group has already evaluated over 2,500 potential varieties in their nine years together, now the team is intent on warping this speed with new technology.

Turf Tech For Breeding

The group’s next phase of research will use drones and remote sensing devices to provide real-time feedback on plant stress – a plant breeder’s dream. But how does a robot sense plant stress?

The drones will be equipped with specialized sensors to detect changes in turf color, ideally even before visible to the human eye. By measuring color change (from stress) over time, researchers can rank the highest performers.

NC State Sandhills Research Station. Photo by Rob Austin.

Technology also brings objectivity to plant breeding. Instead of researchers assigning a visual grade of 1 to 9 on turfgrass color, drone sensors capture a binary “stress/no stress” assessment. It’s black or white – or brown or green, in this case. Removing human bias results in standardized scoring, which is especially important when measurements are taken across hundreds of plots at six universities.

Rob Austin, a GIS specialist at NC State, will oversee the Raleigh group’s data strategy. He sees opportunity in automating the workflow. “We don’t want to simply trade time in the field for time behind a computer screen,” Austin said, “We need standards and processes to translate the data into meaningful results.”

Using this autonomous data collection, breeders can measure more traits, and evaluate more trials, of even more varieties at a time. Increasing the volume of data generated speeds the plant breeding process. Researchers call it ‘high throughput phenotyping” and it delivers fast feedback for streamlined selection of the most resilient samples.

Plant breeding didn’t end in the last project’s phase. It’s the heart of the project, but there’s always room to improve selections and methodology. “Some team members are working to understand what makes a grass more drought tolerant. Others use that information to identify which genes might be responsible for the improved performance,” Milla-Lewis said.

In Practice

The research group is looking to not only refine the turf varieties, but to quantify best management practice guidelines for them. This will involve testing under multiple conditions: restricted rainfall, reclaimed water irrigation, salty-spray exposure, shade, sod strength for cutting, and other production aspects. Surviving these endurance tests will produce turfgrass uniquely adapted for low maintenance production and management.

“We’ve learned in our investigations that the average consumer is concerned about their grass’s environmental tolerance – to shade, drought, and winter-kill. They are looking for low maintenance landscapes,” Milla-Lewis noted.

Convincing homeowners to adopt these drought-tolerant grasses would deliver both environmental benefits and lower maintenance. “We have a young consumer audience with very different landscape needs. For some, lawn maintenance is at best a hobby, and at worst a nuisance. They are looking for lawns requiring fewer inputs, even if it is more expensive,” concluded Miller.

Howard is a communications specialist with the Department of Crop and Soil Sciences at NC State University. This article was edited for Turf magazine. Find the full report here.