MEFLUIDIDE EFFECTS ON YIELD AND QUALITY OF SMOOTH BROMEGRASS

Abstract

Smooth bromegrass (Bromus inermis Leyss.) pastures are characterized by poor seasonal yield distribution and low animal productivity during the late season. The plant growth regulator mefluidide (N-[2,4-dimethyl-5[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide) was applied to smooth bromegrass prior to jointing at 0 (Control), 0.15 (Low) and 0.30 (High) kg ha−1 to effect yield redistribution and improve forage quality in a three-cut system (preboot, cut 2 and cut 3) and in initial stages of growth at preboot, anthesis and hard dough stages. Almost all differences, due to mefluidide treatment, were confined to stages of accumulated growth and to cut 2 of the three-cut regime. Yield distribution was improved over years for both High and Low treatments compared to the Control as a result of decreased preboot and increased cut 2 yields. Total yield for the three cuts was 88% and 83% of the Control for Low and High treatments, respectively. Yield was reduced to 32, 66 and 85% of the Control by the High treatment at preboot, anthesis and hard dough stages of initial growth. Forage quality was generally improved uniformly over stages of initial growth, where leaf to stem ratio increased. Crude protein and in vitro organic matter disappearance (IVOMD) increased, while neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin and cellulose decreased over initial growth stages. IVOMD, NDF, ADF and cellulose increased at cut 2; lignin decreased at cut 3. Mefluidide effectively modified yield distribution in smooth bromegrass, but whether the improvements in forage quality shown through chemical analyses follow through to animal performance must be studied further.Key words: Bromegrass (smooth), mefluidide, yield distribution, forage quality