Trinexapac-ethyl increases Kentucky bluegrass leaf cell density and chlorophyll concentration

The effects of trinexapac-ethyl (TE) on the anatomical and biochemical comp osition of turfgrasses and their implications for its field use are poorly understood. Two greenhouse experiments were conducted to determine if appli cation of TE increased Kentucky bluegrass (Poa pratensis L.) leaf blade cel l density, chlorophyll concentration, or structural carbohydrate content. K entucky bluegrass (KB) sod was harvested from the field, established in gre enhouse pots, and sprayed with 0.27 kg.ha(-1) a.i. TE. Leaf blade samples w ere collected 4 weeks after treatment (WAT), fixed in glutaraldehyde, and e mbedded in Spurr resin. Photomicrographs of longitudinal leaf blade section s were used to determine cell density, cell length, and cell width. Chlorop hyll and structural carbohydrate contents were determined at 2 and 4 WAT. T reatment with TE increased cell density and chlorophyll-b concentration, wh ile reducing cell length, but structural carbohydrate content was unaffecte d. Chemical name used: 4-cyclopropyl-alpha -hydroxy-methylene-3,5dioxo-cycl ohexanecarboxylic acid ethyl ester (trinexapac-ethyl).