Masters Theses

Date of Award

12-1982

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

John H. Reynolds

Committee Members

D. L. Coffey, K. M. Barth

Abstract

Field experiments were conducted in 1981 and 1982 at Knoxville, Tennessee to determine the effectiveness of plant growth regulators on improving the forage quality of tall fescue (Festuca arundinacea Schreb.) and common bermudagrass (Cynodon dactylon (L.) Pers. var. dactylon) through late spring and summer. On May 13, 1981, a tall fescue experiment and a bermudagrass experiment were treated with chlormequat (2-chloroethyl trimethyl ammonium chloride), glyphosine (N, N-bis (phosphonomethyl) glycine), mefluidide (N-2, 4-dimethyl-5- (trifluoromethyl)-sulfonyl-aminophenylacetamide), and ethephon (2-chloroethyl phosphonic acid). On June 29, 1981, tall fescue and bermudagrass experiments were treated with chlormequat, glyphosine, mefluidide, ethephon, and endothall (7-oxabicyclo-(2,2,l)-heptane-2,3,- dicarboxylic acid, disodium salt). On April 15, 1982, a tall fescue experiment was treated with chlormequat, glyphosine, mefluidide, and ethephon. Dry matter production, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, water soluble carbohydrates (WSC), and crude protein were determined from samples taken approximately every three weeks. Bermudagrass showed a few small responses to treatment, and in some cases declined in quality. Tall fescue treated on April 15, 1982, while in the preboot stage, had the greatest increases in quality. Glyphosine reduced NDF by 10.1 and 12.7 percent in the first two sampling dates, and it reduced ADF by 5.6 and 6.8 percent in the first two sampling dates. Structural carbohydrate reductions were also noted in 1981 with glyphosine, and with mefluidide and ethephon in 1981 and 1982. Increases in WSC of 10.7 and 12.3 percent were caused by glyphosine in the first two sampling dates of 1982. Some WSC increases, although not as large, were observed in 1981 from chlormequat, glyphosine, mefluidide, ethephon, and endothall treatments. Crude protein was increased in the first tall fescue experiment of 1981 by mefluidide and ethephon, and in 1982 by glyphosine, mefluidide, and ethephon. There were no differences in lignin or total yield, but yield reductions were observed in several harvests from glyphosine, mefluidide, and ethephon. Results indicate tall fescue quality was improved most by glyphosine applied in the preboot stage, with reductions in cellulose and hemicellulose and increases in WSC the most prominent changes. Further research should be conducted to determine the most effective chemical, rate, date of application for improving forage quality, and the effects of application on stand longevity.

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