Evaluation of plant growth‐promoting rhizobacteria on stockpiled bermudagrass

Abstract

A 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.

Utility of Plant Growth-Promoting Rhizobacteria for Sustainable Production of Bermudagrass Forage

“…In previous work, B20 failed to produce similar forage dry mass as ammonium sulfate when applied during the growing season to potted bermudagrass in simulated field conditions [22]. However, B20 outperformed DH44 in dry mass yield when applied to small field plots in late summer to promote forage growth for stockpiling (standing hand production) [23]. These differences in strain performance may either be based on environmental factors or inherent differences in the ecology of these strains.…”

“…In previous work from our labs [19,[21][22][23], the benefits of adding PGPR, specifically DH44 and B20 alone or with a low rate of fertilizer, to grasses for enhanced growth or quality have been demonstrated in greenhouse and small plot field work. In this study, we used several common variables (dry mass, heights, CP, TDN, ADF, and NDF) to evaluate forage yield and quality following treatment.…”

“…The singlestrain application consisted of Paenibacillus riograndensis strain DH44 (DH44). These strains were selected from collections at Auburn University for their ability to increase growth promotion in bermudagrass based on previous studies [23]. Strains were grown as a bacterial lawn on TSA plates in the lab, then scraped into solution for field applications.…”

“…After initial colonization, strains of PGPR can persist in bermudagrass roots and shoots for 8-12 weeks [21]. Thus far, these strains have only been evaluated in short-term greenhouse [22] or small field plot experiments [23]. The goal of this study was to evaluate PGPR in large forage plots at multiple sites over two years.…”

Co-Inoculation of Trichoderma asperellum with Bacillus subtilis to Promote Growth and Nutrient Absorption in Marandu Grass

“…Grass inoculation with growth-promoting microorganisms has been studied and has shown signifcant results in the growth and reduction of mineral fertilizer [30][31][32]. Te genera applied in this study, with growth-promoting characteristics in other crops, need to be studied as inoculants in the grass, aiming to increase growth and reduce mineral fertilization.…”