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Title: Increased Plant Uptake of Nitrogen from 15N Depleted Fertilizer Using Plant Growth-Promoting Rhizobacteria

Author
item ADESEMOYE, ANTHONY - AUBURN UNIVERSITY
item Torbert, Henry - Allen
item KLOEPPER, JOSEPH - AUBURN UNIVERSITY

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2010
Publication Date: 8/24/2010
Citation: Adesemoye, A.O., Torbert III, H.A., Kloepper, J.W. 2010. Increased plant uptake of nitrogen from 15N depleted fertilizer using plant growth-promoting rhizobacteria. Applied Soil Ecology. 66:54-58.

Interpretive Summary: It has been demonstrated that plant growth-promoting rhizobacteria (PGPR) can potentially promote plant growth. It has been speculated that one of the mechanism for this increased plant growth is stimulated N uptake by plant roots exposed to PGPR. Specifically, it is believe that the increased plant N is a result of increased fertilizer N utilization efficiency. This study used 15N isotope techniques to determine that PGPR could enhance plant uptake of N using different rates of N. Results showed that the dry biomass and N uptake in plants which received 70% to 90% of recommended N fertilizer with PGPR inoculation was comparable to plants that received full rates of fertilizer without PGPR. These results indicate that application of PGPR could be used to reduce fertilizer N application needed for crop production.

Technical Abstract: The techniques of 15N isotope have been very useful for determining the behavior and fate of N in soil, including the use efficiency of applied N fertilizers by plants. Our objective in this study was to use 15N isotope techniques to demonstrate that a model plant growth-promoting rhizobacteria (PGPR) system, a two-strain mixture of Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4, can enhance plant uptake of N using different rates of 15N-depleted ammonium sulphate ([15NH4]2SO4). Results showed that the dry biomass of plants which received 70% to 90% of recommended N fertilizer with PGPR inoculation was comparable to plants that received full rates of fertilizer without PGPR. Also, atom % 15N per gram of tomato tissues decreased as the amount of fertilizer increased and PGPR inoculation had significant impacts on the values. For example, the atom % 15N abundance in plants that received 80% fertilizer plus PGPR was 0.1146, which was significantly lower than 0.1441 for plants that received 80% fertilizer without PGPR but not different significantly from 0.1184 for plants that received 100% fertilizer without PGPR. This study further confirms that PGPR could be used to enhance plant uptake of N from fertilizer as indicated by the differences in d15N and total N in addition to plant growth promotion.