The National Turfgrass Evaluation Program (NTEP) conducts trials throughout the United States on turfgrass adaptation. This trial was established in September 2010 as part of the NTEP program. It contains 88 perennial ryegrass cultivars.
Christians, Nick and Strey, Dan
"NTEP Perennial Ryegrass Study 2015,"
Farm Progress Reports: Vol. 2015
, Article 54.
Available at: http://lib.dr.iastate.edu/farmprogressreports/vol2015/iss1/54