Effects Of Different Light Intensity On Summer Hardiness Of Cool Season Turf Grasses

The turf characters and physiological indexes of 59 cool-season turfgrass varieties of creeping bentgrass(Agrostis stolonifera) and kentucky bluegrass(Poa pratensis) and perennial ryegrass(Lolium perenne) and tall fescue(Festuca arundinacea) were researched under natural lighting (maximum daily light intensity is about 1900μmol·m-2·s-1) and slight shading (maximum daily light intensity is about 1100μmol·m-2·s-1) and medium shading (maximum daily light intensity is about 550μmol·m-2·s-1) and heavy shading (maximum daily light intensity is about 90μmol·m-2·s-1) in summer in Nanjing. It layed a foundation for developing and applying new heat and shade resistant varieyies of turfgrass in city garden construction.The results indicated: the higher the SPAD value of leaves of turfgrass was, the deeper turfgrass was green. The color of leaves was converging with shade density increasing.When maximum daily light intensity was more 550μmol·m-2·s-1, turf quality increased or decreased according to different varieties with shade density increasing. When the maximum daily light intensity was about 1900μmol·m-2·s-1 in summer day, the turf quality of tall fescue TF01 and TF17 was best. When the maximum daily light intensity was about 1100μmol·m-2·s-1 in summer day, the turf quality of creeping bentgrass BT03 and BT06 and BT01 and tall fescue TF05 was better. When the maximum daily light intensity was about 550μmol·m-2·s-1 in summer day, the turf quality of creeping bentgrass BT01 and BT03 and BT06 was better.When maximum daily light intensity was less than 90μmol·m-2·s-1, the turf quality of every experimental variety was worse, and at this time more heat and shade resistant ground cover should be selected.When maximum daily light intensity was between 550μmol·m-2·s-1 and 1900μmol·m-2·s-1, the width of leaves of each experimental variety of kentucky bluegrass and tall fescue became narrower with shade density increasing, the width of leaves of most varieties of creeping bentgrass and perennial ryegrass changed indistinctively. When maximum daily light intensity was less than 90μmol·m-2·s-1, the width of leaves of all turfgrass varieties became needle-leaved.In the definite scope of light intensity, the growing rate of some varieties rised with shade density increasing, but the growing rate of others was no significant change. When maximum daily light intensity was less than 90μmol·m-2·s-1, the growth of all the experimental varieties was suppressed. When maximum daily light intensity was between 550μmol·m-2·s-1 and 1900μmol·m-2·s-1, all the...