EFFECTS OF VARIOUS PLANT GROWTH REGULATORS ON THE NUTRITIVE VALUE AND YIELD OF SOME GRASS SPECIES, RED CLOVER AND GRASS-LEGUME MIXTURES
Authors: BUCK D. C. , COHEN R. D. H. , CHRISTENSEN D. A. 
Published: March 2010

Plant growth regulators (PGRs) were evaluated on smooth bromegrass, timothy, meadow foxtail, red clover, red clover-timothy and alfalfa-smooth bromegrass mixtures with respect to the following quality parameters; acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, crude protein (CP), calcium, phosphorus, digestible protein (DP), intake per kilogram body weight (INTBW), percent in vivo digestibility (IVD), dry matter (DM) yield and where applicable proportion (%) of grass in a forage mixture. PGRs mefluidide and chlormequat were applied to the grasses at growth stages 6 and 9 (Feekes scale) and to the red clover at the mid-vegetative and bud stage in 112 and 225 L ha−1 water whereas maleic hydrazide, ancymidol, daminozide, dicamba, 2,4-DB, MCPB, flamprop methyl, accel and carbofuran were applied to the grasses at growth stage 6 (Feekes scale) and to red clover at the mid-vegetative growth stage in 112 L/ha water, Application timing for the forage mixtures was based on the grass growth in the sward (growth stage 6 and/or 9 of Feekes scale). For smooth bromegrass and meadow foxtail, ADF, NDF, phosphorus and lignin were reduced (P < 0.05) by mefluidide and chlormequat whereas these compounds increased (P < 0.05) the CP content of smooth bromegrass and timothy and increased (P < 0.05) lignin, phosphorus and calcium in timothy. Chlormequat increased (P < 0.05) cell wall components in timothy. Maleic hydrazide increased (P < 0.05) the calcium content of smooth bromegrass and decreased (P < 0.05) NDF in timothy. The NDF content of smooth bromegrass was decreased by 2,4-DB (P < 0.05) and increased by MCPB (P < 0.05). In timothy dicamba increased (P < 0.05) NDF and accel increased (P < 0.05) lignin and calcium. Time of application and water volume had inconsistent effects across these grass species. Red clover cell-wall components were significantly (P < 0.05) reduced and CP and DP significantly (P < 0.05) increased by chlormequat and daminozide in some trials whereas cell wall was significantly (P < 0.05) increased by mefluidide and accel. Phosphorus was significantly (P < 0.05) increased by chlormequat, daminozide, accel, MCPB and 2,4-DB in some test years. Timing of mefluidide application significantly (P < 0.05) reduced CP and DP and significantly (P < 0.01) increased INTBW in 1984. In 1982 NDF and % grass were significantly (P < 0.05) reduced by mefluidide in the red clover-timothy mixture while CP was significantly (P < 0.01) increased. In 1983 only % grass was significantly (P < 0.05) reduced. Chlormequat significantly (P < 0.05) reduced cell-wall components in 1982 and 1983 while % grass was significantly (P < 0.05) reduced only in 1983. Mefluidide-treated alfalfa-smooth bromegrass had a significantly lower % grass component in 1982 and 1983 (P < 0.05) whereas other responses were inconsistant. Chlormequat significantly increased cell wall (P < 0.01), protein (P < 0.05) and phosphorus (P < 0.05) in 1982. Responses to timing of application and water volume used were inconsistant.Key words: Mefluidide, chlormequat, daminozide, accel, MCPB, 2,4-DB