Evaluation of plant growth‐promoting rhizobacteria on stockpiled bermudagrass

Abstract

AbstractA two‐year, small‐plot study was conducted to evaluate plant growth‐promoting rhizobacteria (PGPR) for biofertilization of fall‐stockpiled bermudagrass [Cynodon dactylon (L.) Pres.]. Eighteen, 10.8‐ft2 bermudagrass (cultivar ‘Coastal’) plots were mowed to 1‐inch stubble height prior to stockpiling. Experimental treatments included a negative control, synthetic fertilizer, PGPR single‐strain DH 44, DH 44 + fertilizer, PGPR multiple‐strain Blend 20, and Blend 20 + fertilizer (n = 3). Two PGPR applications were made, one at the beginning of each stockpiling season in mid‐August, and again 30 days later. Ammonium sulfate was applied at 50 lb N/acre concurrent with the first PGPR application. Each plot was divided into three subplots, which were harvested at different periods (i.e., mid‐November, mid‐December, and mid‐January) of each year to determine forage dry matter (DM) yield and nutritive value. Forage DM yield was greatest (P ≤ .03) for Blend 20 + fertilizer, but it was not different (P = .26) from that of the synthetic fertilizer treatment. Concentration of crude protein was least (P < .04) for DH 44 and Blend 20 treatments. Concentrations of acid detergent fiber were not different among treatments, except for the negative control which was lower (P < .05). In vitro true digestibility was not different (P < .05) among treatments. These results indicate that PGPR may be a viable option for biofertilization; however, further investigation into the effect of PGPR inoculants at field level is needed.