Growth regulator effects on turfgrass characteristics

Plant growth regulators (PGRs) are commonly used throughout the turfgrass industry to reduce mowing requirements. Research was conduced to identify the effects of trinexapac-ethyl [4-cyclopropyl-alpha-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid methyl ester] (TE) and mefluidide [N-(2,4-dimethyl-5-{lcub}[trifluoromethyl)sulfonyl]amino{rcub}phenyl) acetamide] on turfgrass characteristics and determine how these results might impact turfgrass management practices.; Experiments were conducted to determine the effect of multiple pre-harvest applications of TE at 0.23 kg ha-1 on Kentucky bluegrass (Poa pratensis L.) sod temperatures during storage. Mean sod temperatures in separate experiments were 3°C cooler in TE treated sod. These results suggest that TE could be used by sod growers to extend storage times by several hours and increase shipping and market areas.; Adequate tensile strength is a necessary quality for growing marketable turfgrass sod. Experiments were conducted at Mead, NE and Cedar Rapids, IA, during the summers of 2000 and 2001. Trinexapac-ethyl was applied to Kentucky bluegrass every 4 wk (0.23 kg ha-1) or every 2 wk (0.12 kg ha-1). Trinexapac-ethyl every 2 wk resulted in less consistent results, but increased tensile strength as much as 163% over the control. The use of TE may allow sod producers to develop adequate sod tensile strength faster.; Two greenhouse experiments were conducted to determine the influence of TE on the chlorophyll content of Kentucky bluegrass. Total chlorophyll content increased by 26%, with a single TE application of 0.45 kg ha -1. Two greenhouse experiments using tall fescue cv. Mustang (Festuca arundinacea Schreb.) and St. Augustinegrass cv. Raleigh [Stenotaphrum secundatum S. (Walt.) Kuntze] were conducted also to determine the affect of PGRs on cell density. St. Augustinegrass and tall fescue were treated with TE at 0.286 kg ha-1 and 0.145 kg ha-1, respectively, and mefluidide at 0.137 kg ha-1 for both species. Tall fescue and St. Augustinegrass cell density increased 15 and 20%, respectively, from both PGR treatments. Increased cell density and greater chlorophyll content could enhance irradiance capture of both species under low light conditions.