An Analysis of the Carbohydrate Status of Mefluidide‐Treated Annual Bluegrass

Abstract

Abstract The intense spring seedhead production of annual bluegrass ( Poa annua L.) is a major factor limiting its quality as a turfgrass. Developing seeds are unsightly, and monopolization of assimilates by developing seeds may be partially responsible for the shallow root system and poor stress tolerance of annual bluegrass. A greenhouse study was conducted to determine if seedhead suppression resulting from the plant growth regulator mefluidide [ N (2,4‐dimethyl‐5‐{[(trifluoromethyl)sulfonyl]amino} phenyl) acetamide] would result in a redistribution of carbohydrates to the roots of annual bluegrass. Mefluidide was applied prior to seedhead emergence at rates ranging from 0 to 0.21 kg a.i. ha −1 . Complete seedhead suppression associated with the 0.14 and 0.21 kg a.i. ha −1 rates resulted in greater concentrations of fructose and glucose in annual bluegrass roots compared to roots of untreated plants during peak seedhead emergence. Redistribution of carbohydrates was short lived, with no differences in carbohydrate content occurring among treatments after peak seedhead emergence. Mefluidide had little effect on leaf and stem carbohydrates. Regardless of mefluidide rate, concentrations of fructose, sucrose, and fructans were considerably greater in leaf and stem tissue than in roots. Annual bluegrass stems were the major storage organ for fructans, with only minor fructan storage occurring in roots. The carbohydrate content of mefluidide‐treated annual bluegrass decreased substantially in leaf, stem, and root tissue following growth inhibition due to a post‐inhibition growth surge.