Trinexapac-ethyl Does Not Increase Total Nonstructural Carbohydrate Content in Leaves, Crowns, and Roots of Tall Fescue

Abstract

Turfgrass growth regulators (TGRs) are an effective means of reducing vertical shoot growth and the production of clippings of tall fescue (Festuca arundinacea Schreb.). Recently, using TGRs has been suggested as a way to acclimate or precondition turfgrass to stress conditions, possibly through total nonstructural carbohydrate (TNC) accumulations and altered TNC partitioning. The TNC may accumulate in response to growth suppression associated with the TGR application. The objective of this study on tall fescue was to determine the effect of a single trinexapac-ethyl (TE) application on tissue weight and on TNC concentration and weight in leaves, crowns, and roots when sampled 6 to 7 weeks following TE application. This sampling time was chosen to coincide with the 28- to 56-day callback schedule that professional lawn care personnel follow when working with tall fescue. In 1995, a high level of turfgrass maintenance was used, consisting of N applications at 49 kg·ha-1 per month and two mowings per week, while in 1996 a moderate level was used, consisting of N applications at 24 kg·ha-1 per month and one mowing per week. Though TE provided reasonable inhibition of clipping growth for a 4-week period during both years, we observed no increase in tissue weight or in TNC concentration or weight in leaves, crowns, and roots when sampled 6 to 7 weeks after treatment. Chemical name used: [4(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] (trinexapac-ethyl).