Rice plant is one of the most common food crops cultivated in numerous countries. Over 150 million tons of rice hulls are expected to be produced around the world. Therefore, effective utilization of rice hulls is very important for both treatment of an agricultural waste material and creating sustainable agriculture. Rice husk biochar (RHB) is produced by low-temperature pyrolysis of rice hulls, and has been used as a soil amendment for the better drainage properties and air permeability. Another advantage in RHB addition has been considered to increase the plant growth promoting microbes. We had focused on the relationships between microorganisms and RHB and tried to isolate the microorganisms whose growth is promoted in the presence of RHB. In a previous study, we successfully isolated Bacillus sp. strain IA, whose growth was promoted on agar plate supplemented with RHB than the growth on the plate without RHB. Furthermore, strain IA’s growth, sporulation and an antibiotic production were promoted by the addition of RHB to the liquid culture medium. These results suggested that a combination of strain IA and RHB will be an effective biocontrol agent. This study aimed to develop a biocontrol agent combined with strain IA and RHB. To evaluate an ability for a plant protection, cucumbers were grown in soil with strain IA and then a phytopathogenic fungus Rhizoctonia solani K1 was inoculated onto the soil. As a result, the soil with strain IA showed a reduction of the disease level of cucumber than that without strain IA. To develop a low-cost biocontrol agent, we attempted cultivation of strain IA using rice bran, which is an agricultural waste material from rice plant. A medium, combined with RHB and rice bran, was developed and used for the cultivation of strain IA. As a result of cultivation, strain IA could grow in the medium with a combination of RHB and rice bran to the level of 108 cfu per 1 g of RHB. This study showed possibility that the combination of strain IA, RHB and rice bran will be an effective and a low-cost biocontrol agent to control plant diseases.

Development of a biocontrol agent using rice husk biochar with Bacillus sp. IA

2019 Fall National Meeting

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