A study on heat tolerance of five coolseason turfgrasses

The experiment was conducted to investigate heat tolerance of the five kinds of coolseason grasses, including Festuca arundinacea, Lolium perenne,Agrostis stolonifera, Poa pratensis and P. trivialis, through analyzing apparent indexes: green leaf number/plant and growth height; and physiologicalbiochemical indexes: relative water content, relative electric conductivity, chlorophyll content, SOD activity, CAT activity and POD activity, in artificial climatic chamber with high temperature (35 ℃/30 ℃, day/night) and high humidity (75%). The result showed that at high temperature (day/night, 35 ℃/30 ℃), the relative water content of five grasses decreased; and the relative electric conductivity of five grasses increased with threatened time increasing. The change of leaf chlorophyll content of five grasses was not consistence. The chlorophyll content of F. arundinacea, L. perenne and P. pratensis showed increased at first and then decreased; and the chlorophyll content of other two species decreased all the time. The SOD and POD activities of five grasses increased firstly and then decreased. CAT activity decreased all the time. The green leaf number/plant and plant growth height of five grasses decreased with threatened time increasing. The five grasses were classified three groups by a cluster analysis. The first group (heat tolerance) was F. arundinacea; the second group (moderate heat tolerance) were P. pratensis, L.perenne and A. stolonifera; and the third group (sensitive to heat) was P. trivialis.