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Agronomy Journal Abstract -

Plant Growth Regulator Effects on Growth and Forage Quality of Tall Fescue


This article in AJ

  1. Vol. 85 No. 3, p. 545-548
    Received: June 6, 1991

    * Corresponding author(s):
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  1. J. H. Reynolds ,
  2. W. A. Krueger,
  3. C. L. Walker and
  4. J. C. Waller
  1. D ep. of Plant & Soil Science
    D ep. of Animal Science, Univ. of Tennessee, Knoxville, TN 37901-1071



Forage quality of tall fescue (Festuca arundinacea Schreb.) is low in the spring after heading. Plant growth regulators (PGRs) have been shown to improve forage quality through inhibition of seedhead development. The objective of this study was to compare the effect of fall or spring application of six PGRs on heading, yield, and forage quality of tall fescue. The soil was an Etowah silt loam (fine-loamy, siliceous, thermic Typic Paleudults). Precipitation was more favorable in the second year of the experiment than in the first. Sethoxydim (2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) at 70 g ha−1, haloxyfop methyl (methyl 2-[4-[[3-chloro-5-trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid) at 45 g ha−1, and mefluidide (N-[2,4-dimethyl-5-[[(trifluoromethyl)-sulfonyl]amino]phenyl]acetamide) at 280 g ha−1 were the most consistent in reducing head density, forage yield, and neutral detergent fiber (NDF) and increasing crude protein (CP) of the May harvest. The PGRs were more effective in reducing yield, head density, and NDF and increasing CP of the May harvest when applied in April than when applied in December of the second year. Responses to the PGRs in the May harvest were fewer in the first year when precipitation was less favorable. Only one PGR increased in vitro dry matter digestibility (IVDMD) in the second year and none increased it in the first year. Four April-applied PGRs decreased NDF in the first year's regrowth and April-applied sethoxydim and December-applied mefluidide increased CP in both years' regrowth. Forage quality was not consistently improved by the use of PGRs on tall fescue. An effective PGR may be more useful in turf areas than on forage because it reduces yield substantially.

Contribution from the Tennessee Agric. Exp. Stn.

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