Semilethal high temperature and heat tolerance of twelve varieties of Lolium perenne

The heat tolerance of twelve varieties of Lolium perenne was tested with the electrical conductivity method. A sigmoid response curve with Logistic equation existed between the rate of injured cells of leaves and treatment temperature. The semilethal temperature obtained by seeking the point of inflexion on the curve. The heat tolerance of six turfgrass varieties in the decreased order were Accent, Cutter, Pinnacle, Bartwingo, Premier and Fairway, and for six forage varieties in the decreased order were Yatsyn, Oupec, Nul, Tove, Polim and Eminent.