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ARS Home » Southeast Area » Stoneville, Mississippi » Biological Control of Pests Research » Research » Research Project #438284

Research Project: Biochar as a Tool for Preventing Root Infection of Soybean Seedlings by Macrophomina Phaseolina and Other Soil Fungi

Location: Biological Control of Pests Research

Project Number: 6066-42000-006-12-A
Project Type: Cooperative Agreement

Start Date: Apr 1, 2020
End Date: Jan 31, 2021

The objective of the proposed research is to determine if biochar can be used to protect germinating soybean seeds from root infection by fungi in the soil, including M. phaseolina. It is proposed approach to using biochar that will be examined by incorporating biochar into bioplastic-based seed coatings.

It is proposed to investigate ways to protect soybean root tips from fungal infection by having root growth pass through biochar in swollen seed coating that can bind toxins such as (-)-botyrodiplodin and prevent root infection. Initial studies need to be conducted to determine optimal biochar-bioplastic mixtures for binding (-)-botyrodiplodin and other mycotoxins with respect to both % biochar and the effect of biochar particle size on toxin binding effectiveness. The effectiveness adding biochar to the seed coatings at preventing root infection of soybean seedlings will be determined in the greenhouse using soils contaminated with M. phaseolina or other fungal pathogens of soybean and in the field. Use of biochar-based seed coatings could be relatively simple to implement. This laboratory has carried out extensive studies on bioplastic-based seed coatings as vehicles for spores of biocontrol fungi and chemical pesticides. These studies have used bioplastic consisting of partially acetylated (8% acetylation) cornstarch. This percent acetylation gives hard seed coatings with minimal dust-off during handling. After planting, the seed coatings are assumed to imbibe water and swell. The proposed use of seed coatings impregnated with biochar would be expected to benefit from using bioplastic compositions that give relatively rapid and more extensive water imbibing and resulting swelling to provide a larger zone for the seedling root to pass through than might be optimal for serving as a biocontrol and pesticide vehicle. It is expected that bioplastics with a lower percent acetylation would provide better swelling and thus a larger safe zone for soybean seedling root growth. Bioplastics with 3%, 4%, 5%, 6%, 7% and 8% acetylation will be tested as carriers of biochar over a range of concentrations (2%, 5%, 10%, 20% and 25% wt/wt in bioplastic). The various seed treatments will be evaluated for effects on seed germination rate and resistance to infection by M. phaseolina from contaminated soil in the greenhouse. Charcoal coatings on seeds are not expected to reduce germination rates, because charcoal would be expected bind germination inhibitors, if it had any effect.