Assessment of Bacterial Inoculant Delivery Methods for Cereal Crops

Journal Article · 25 January 2022 · Frontiers in Microbiology

DOI: https://doi.org/10.3389/fmicb.2022.791110 · OSTI ID:1904452

Chai, Yen Ning ^[1]; Futrell, Stephanie ^[2]; Schachtman, Daniel P. ^[2]

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1. University of Nebraska, Lincoln, NE (United States); Univ. of Nebraska, Lincoln, NE (United States)
2. University of Nebraska, Lincoln, NE (United States)

Despite growing evidence that plant growth-promoting bacteria can be used to improve crop vigor, a comparison of the different methods of delivery to determine which is optimal has not been published. An optimal inoculation method ensures that the inoculant colonizes the host plant so that its potential for plant growth-promotion is fully evaluated. The objective of this study was to compare the efficacy of three seed coating methods, seedling priming, and soil drench for delivering three bacterial inoculants to the sorghum rhizosphere and root endosphere. The methods were compared across multiple time points under axenic conditions and colonization efficiency was determined by quantitative polymerase chain reaction (qPCR). Two seed coating methods were also assessed in the field to test the reproducibility of the greenhouse results under non-sterile conditions. In the greenhouse seed coating methods were more successful in delivering the Gram-positive inoculant (Terrabacter sp.) while better colonization from the Gram-negative bacteria (Chitinophaga pinensis and Caulobacter rhizosphaerae) was observed with seedling priming and soil drench. This suggested that Gram-positive bacteria may be more suitable for the seed coating methods possibly because of their thick peptidoglycan cell wall. We also demonstrated that prolonged seed coating for 12 h could effectively enhance the colonization of C. pinensis, an endophytic bacterium, but not the rhizosphere colonizing C. rhizosphaerae. In the field only a small amount of inoculant was detected in the rhizosphere. This comparison demonstrates the importance of using the appropriate inoculation method for testing different types of bacteria for their plant growth-promotion potential.

• Research Organization: University of Nebraska, Lincoln, NE (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: SC0014395
• OSTI ID: 1904452
• Journal Information: Frontiers in Microbiology, Journal Name: Frontiers in Microbiology Vol. 13; ISSN 1664-302X
• Publisher: Frontiers Research FoundationCopyright Statement
• Country of Publication: United States
• Language: English