Effect of plant growth promoting rhizobacteria at various nitrogen rates on corn growth

Authors: LIN, YARU - Auburn University; Watts, Dexter; KLOEPPER, JOSEPH - Auburn University; ADESEMOYE, ANTHONY - University Of Nebraska; FENG, YUCHENG - Auburn University

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2019
Publication Date: 12/11/2019
Citation: Lin, Y., Watts, D.B., Kloepper, J.W., Adesemoye, A.O., Feng, Y. 2019. Effect of plant growth promoting rhizobacteria at various nitrogen rates on corn growth. Agricultural Sciences. 10:1542-1565. https://doi.org/10.4236/as.2019.1012114.
DOI: https://doi.org/10.4236/as.2019.1012114

Interpretive Summary: Plant growth-promoting rhizobacteria (PGPR) are free-living bacteria in soil that often live around the plant roots and promote plant growth. Recently there has been interest in using these free-living bacteria to improve the amount of nutrients taken up by plants from soil and potentially decrease the amount of chemical fertilizers needed for crop production. Thus, a greenhouse container study was conducted to determine the influence of PGPR on corn biomass production and nitrogen content of plants evaluated under different N levels. The N levels for this study consisted of applying 0, 25, 50, 75, and 100% of the recommended rate needed to optimize crop production from an Alabama Coastal Plain Soil. The use of PGPR resulted in increases of plant height, stem diameter, leaf area, and root growth at the V6 growth stage, but few differences were observed at the V4 stage. Applying PGPR at 50% of the full recommended N rate produced corn biomass similar to that at the full rate without PGPR inoculants when measured at the VT growth stage.

Technical Abstract: Plant growth-promoting rhizobacteria (PGPR) colonize plants roots and promote plant growth by producing and secreting various chemical regulators in the rhizosphere. With the recent interest in sustainable agriculture, an increasing number of researchers are investigating ways to improve the efficiency of PGPR use to reduce chemical fertilizer inputs needed for crop production. Accordingly, greenhouse studies were conducted to evaluate the impact of PGPR inoculants on biomass production and nitrogen (N) content of corn (Zea mays L.) under different N levels. Treatments included three PGPR inoculants (two mixtures of PGPR strains and one control without PGPR) and five N application levels (0, 25, 50, 75, and 100% of the recommended N rate of 135 kg N ha-1). Results showed that inoculation of PGPR significantly increased plant height, stem diameter, leaf area, and root morphology of corn compared to no PGPR application under the same N levels at the V6 growth stage, but few differences were observed at the V4 stage. PGPR with 50% of the full N rate produced corn biomass and N concentration equivalent to or greater than that of the full N rate without inoculants at the VT stage. In conclusion, mixtures of PGPR can potentially reduce inorganic N fertilization without affecting corn plant growth parameters. Future research is needed under field conditions to determine if these PGPR inoculants can be integrated as a bio-fertilizer in crop production nutrient management strategies. Future research is needed to evaluate the influence of PGPR on plant growth when fertility requirements are not optimal.