Effects of Biocontrol Bacteria and Earthworms Onaphanomyces Euteichesroot-Rot and Growth of Peas (pisum Sativum) Studied in a Pot Experiment

ABSTRACT The role of below-ground interactions between microbial biocontrol agents and soil fauna for combatting soil-borne plant diseases have not been studied sufficiently. This study tested the hypothesis that the beneficial bacterium Bacillus velezensis UCMB5113 and the anecic earthworm Lumbricus terrestris positively influence health and growth of peas (Pisum sativum L.) infested with the pathogen Aphanomyces euteiches causing root-rot disease. A greenhouse fully factorial experiment studied the effects of A. euteches, B. velezensis and L. terrestris on the emergence, growth and health of pea plants. The factors B. velezensis and L. terrestris resulted in taller plants (p = .003 and p = .030). B. velezensis treatment resulted in a higher biomass of shoots and roots (p ≤ .001 and p = .005). The effects increased with the presence of both factors (p = .036). Earthworms reduced the disease symptoms significantly (p = .032). The decreased disease symptoms caused by the earthworms might be due to the consumption of A. euteiches (direct effect) as well as soil disturbance (indirect effect). Interactions between the microorganisms added and the earthworms were shown. B. velezensis and L. terrestris can be useful for enhancement of plant growth and for biological control of root-rot in peas.