Suppression of waterborne diseases using Bacillus subtilis var. natto in hydroponic cultures

Plants cultured in hydroponic systems, especially using the deep flow technique (DFT), are often sensitive to waterborne diseases caused by plant pathogens such as Pythium spp.
Diseases can spread easily and intensify in DFT culture because microflora in nutrient solutions are usually scant.
However, plant diseases can often be suppressed using pre-colonized microorganisms that are harmless to the plants. Bacillus is a representative bacterium of this type used in biocontrol.
This study investigated the potential of Bacillus subtilis var. natto for suppressing waterborne diseases in hydroponic systems.
Lettuce and spinach plants cultivated in DFT are pre-inoculated with B. subtilis var. natto isolated from natto sold commercially before inoculation of each pathogen.
In the trial of lettuce, root rot was suppressed significantly by B. subtilis var. natto. In the trial of spinach, reduction of plant weight was suppressed.
Moreover, B. subtilis var. natto was reisolated from the lettuce and spinach roots after cultivation.
These results indicate that B. subtilis var. natto can colonize roots of these plants and can suppress diseases under hydroponic conditions.
We conclude that B. subtilis var. natto has the potential to suppress waterborne diseases in hydroponic cultures.

XXXI International Horticultural Congress (IHC2022): International Symposium on Sustainable Control of Pests and Diseases

T. Wada, K. Sudo, T. Usami

biocontrol, deep flow technique, DFT, lettuce, plant disease, pythium, spinach

https://doi.org/10.17660/ActaHortic.2023.1378.1