Effect of Plant Growth-Promoting Rhizobacteria at Various Nitrogen Rates on Corn Growth

Yaru Lin,Joseph W Kloepper,Anthony O Adesemoye,Dexter B Watts,Yucheng Feng

doi:10.4236/as.2019.1012114

Abstract

Plant growth-promoting rhizobacteria (PGPR) colonize plant 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 concentrations 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.

Highlights

Commercial fertilizers, especially N sources, are essential for maintaining global crop production and fulfilling food requirements for a rapidly growing world population with limited land resources [1] [2] [3] [4]
Results showed that inoculation of Plant growth-promoting rhizobacteria (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
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

Summary

Introduction

Commercial fertilizers, especially N sources, are essential for maintaining global crop production and fulfilling food requirements for a rapidly growing world population with limited land resources [1] [2] [3] [4]. In 2014, over 11.7 million tonnes of N fertilizer were applied to US agricultural crops [5] This number is expected to increase in the coming years because inorganic N is an indispensable input in crop production. Over half of the N applied can be lost from agricultural systems as gaseous loss (N2, nitrous oxide, NH3 etc.), runoff (NO3), or leaching (NO3) into groundwater [9] [10]. Changing this poor NUE requires more effective management practices

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Conclusion