Project Details:

Title:
Development of New Biological Agents for Seed Treatment and Biofertilization to Promote Soybean Growth

Parent Project: Development of New Biological Agents for Seed Treatment and Biofertilization to Promote Soybean Growth
Checkoff Organization:Louisiana Soybean and Grain Research and Promotion Board
Categories:Agronomy, Soil fertility
Organization Project Code:
Project Year:2020
Lead Principal Investigator:Jong Hyun Ham (Louisiana State University AgCenter)
Co-Principal Investigators:
Keywords:

Information and Results

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Project Summary

Seed treatment (or seed coating) is an economical and environment-friendly way for application of functional materials to protect soybean plants from various biotic and abiotic stresses because relatively smaller amounts of material are required for seed treatment compared to foliar spraying or soil drenching. A diverse array of functional (biotic or abiotic) materials can be applied to soybean seeds for the enhancement of plant growth, which can be achieved through various mechanisms, including suppression of pathogens, elevation of nutrient uptake conditions, and production of plant growth hormones. The PI (Dr. Ham)’s laboratory has constructed a large collection of soybean-associated beneficial bacteria (SABBs), which have various types of biological activities for promoting soybean growth. In this project, these bacterial agents are used as the primary materials for seed treatment along with chitosan and biochar, based on the hypothesis that treatment of multiple agents having different beneficial activities would result in additive or synergistic growth-promoting effects. Accordingly, bacterial consortia composed of multiple beneficial bacteria have been tested for their growth-promoting activities in the presence or absence of chitosan and biochar.

Pelletization of fertilizing materials is another way for sustainable management of soybean production because of its several merits, including reduction of nutrient runoffs and leachate water. In this project, pelletizing protocol for the mixture of poultry manure, biochar and chitosan is optimized, and the resultant products are tested for their efficacy in comparison with a commercial fertilizer. Furthermore, beneficial bacterial of soybean are incorporated into the pelletized fertilizers to enhance their fertilizing functions. The overall goal of this project is to develop innovative methods for sustainable production of soybean using beneficial soybean-associated bacteria and functional materials derived from agricultural byproducts (i.e. biochar and chitosan).

Twenty-six bacterial agents were selected among the soybean-associated beneficial bacteria (SABBs) screened based on the laboratory tests for their effects on seed germination and seedling growth of soybean, as well as their antimicrobial activity, IAA production, siderophore production, and extracellular phosphatase activity. Three bacterial consortia (i.e. Set-1, Set-2, and Set-3) were made using multiple bacterial agents derived from the 26 selected bacterial agents, based on the compatibility among the bacterial components. Two of the three bacterial consortia tested (i.e. Set-1 and Set-2) have shown higher growth-promoting activities on soybean plants than any of the individual bacterial agents alone in the greenhouse tests. Meanwhile, three SABBs that previously exhibited excellent growth-promoting activities were tested again in greenhouse and field conditions for validation of their growth-promoting activities. All of the three SABBs showed equivalent or better growth-promoting activities compared to the commercial seed-treating product (fungicide) used for comparison in this project.

Laboratory and greenhouse tests involving pelletized poultry manure, biochar and chitosan were also conducted in 2019. In the laboratory tests using germination pouches, combinational seed treatments with a SABB along with chitosan and biochar or with chitosan and pelletized poultry manure suppressed the disease caused by the artificial inoculation of Rhizoctonia solani at a comparable level with a commercial seed treatment. Pelletized poultry manure also exhibited a better performance of fertilization for soybean growth in greenhouse tests compared with a commercial fertilizer.

Project Objectives

1: Develop new seed-treating formulations that promote soybean growth
2: Characterize the microbial community of soybean associated with growth promotion
3: Develop new biofertilizers that enhance soybean growth

Project Deliverables

For Objectives 1 and 2. Bacterial agents having beneficial activities for soybean growth will continue to be selected among soybean-associated bacteria, and they will be identified based on 16S rDNA sequence information. New bacterial consortia will be constructed and tested along with the previously chosen ones (Set-1 and Set-2) for their growth-promoting activities. Further, they will be tested in the pots filled with field soil for preliminary evaluation of their growth-promoting functions in the field soil condition. Two best-performing bacterial consortia will be chosen to extract DNA samples of the rhizospheric microbiomes from the treated plants for characterization of the microbial community affected by the treated bacterial consortia.

For Objective 3. Effects of the seed treatments with biochar and chitosan on the growth of soybean plants and the suppression of disease development caused by R. solani will be investigated in the greenhouse along with selected bacterial agents and their consortia. Pelletized poultry manure will be modified by addition of biochar, chitosan and biological agents with various combinations. Up to 10 different pelletized formulations will be tested in the greenhouse for their fertilizing efficacy in comparison with a commercial fertilizer. Effects of the pelletized formulations on the suppression of soybean disease will also be evaluated by inoculation of soybean plants with the soybean pathogen, R. solani. Two best-performing formulations on both soybean growth and disease suppression will be chosen for validation trials in the next year in both greenhouse and field conditions.

Progress of Work

Final Project Results

Benefit to Soybean Farmers

Development of a biological seed treatment and pelletized biofertilizer option that is competitive with current commercial products, but with less environmental impact.

Performance Metrics

• Among three bacterial consortia (Set-1, Set-2, and Set-3) composed of multiple beneficial bacterial agents, two bacterial consortia (Set-1 and Set-2) exhibited higher growth-promoting activities on soybean plants than any of the individual bacterial agents alone in the greenhouse tests.

• Three soybean-associated beneficial bacteria (SABBs), which previously exhibited good growth-promoting activities in greenhouse tests, showed equivalent or better growth-promoting activities compared with the commercial seed-treating product (fungicide) used for comparison in greenhouse and field tests.

• Pelletized poultry manure exhibited a better performance of fertilization for soybean growth in greenhouse tests compared with the commercial fertilizer used for comparison in greenhouse tests.

• Combinational seed treatments with a SABB along with chitosan and biochar or with chitosan and pelletized poultry manure suppressed the disease caused by the artificial inoculation of Rhizoctonia solani at a comparable level with the commercial seed treatment product.

Project Years