Mefluidide Effects on Forage Quality of Crested Wheatgrass1

Abstract

AbstractCrested wheatgrass, (Agropyron desertorum [Fisch.] Schult), a valuable spring forage in semiarid environments, produces stiff reproductive shoots that become unpalatable and are of poor nutritive quality. Mefluidide (N‐[2,4‐dimethyl‐ 5{[(trifluoromethyl)sulfonyl] amino} phenyl]acetamide), a plant growth regulator, has the potential to reduce reproductive shoots and improve nutritive quality. Mefluidide was applied to crested wheatgrass, which was grown on coarse‐loamy, mixed, frigid Orthid Durixerolls in May 1982 and 1983, at 0.14, 0.28, and 0.42 kg a.i. ha−1. Herbage yield, density of reproductive shoots, and concentrations of ash, acid insoluble residues, total N (crude protein), in vitro digestible organic matter (IVDOM), and neutral detergent fiber (NDF) in accumulated forage during July through October were determined each year. Reproductive shoot density was reduced by mefluidide up to 91% in both years. The reduction in reproductive shoot density was accompanied by a 20 to 60% decrease in dry matter yields. Ash contents increased 50 to 70 g kg−1 with mefluidide application. A relatively large portion of the ash was acid insoluble residue (silica) and may have been the result of soil contamination on leaves of treated plants. Mefluidide also increased crude protein 18 to 19 g kg−1 and IVDOM 30 to 40 g kg−1, and decreased NDF 50 to 80 g kg−1. The greatest changes occurred with the 0.28 and 0.42 kg ha−1 rates. Major benefits of mefluidide applications include increased forage quality and decreased stemminess.