The National Turfgrass Evaluation Program (NTEP) conducts trials throughout the United States on turfgrass adaptation. This trial was established in September 2016 as part of the NTEP program. It contains 114 perennial ryegrass cultivars.
Christians, Nick; Thoms, Adam; and Mertz, Isaac
"NTEP Perennial Ryegrass Study,"
Farm Progress Reports: Vol. 2016
, Article 42.
Available at: http://lib.dr.iastate.edu/farmprogressreports/vol2016/iss1/42