Effect of some Bacillus Species Combined with Chemical Resistance Inducers on Control of Pea Damping-off and Root-rot Diseases

Abstract

The isolated fungi of Alternaria sp., Fusarium semitectum, F. solani, Rhizoctonia solani, and fungus-like Pythium ultimum caused pre-and post-emergence damping-off to pea plants. In the pathogenicity test, the fungus Fusarium solani showed the highest percentages of pre-and postemergence damping-off followed by Rhizoctonia solani and F. semitectum. Meanwhile, Alternaria sp. caused the least figures of pre-and post-damping-off followed by fungus-like Pythium ultimum. Data demonstrated that the tested bioagents Bacillus megaterium, B. subtilis and B. thuringiensis and the CRIs resulted in a significant reduction to the linear growth of both F. solani and R. solani compared with control treatment with reduction-concentration dependent. In addition, CRIs were less efficient in this regard than the bioagents. The obtained results revealed that soaking pea seeds in 100 mM Bion (BTH) for six hours, then pelleting them with supernatant of B. megaterium resulted in a significant reduction to the incidence of damping-off and root-rot severity caused by both tested fungi. Also, a significant increase to the plant height and the produced green pods yield was recorded compared to control treatment. Moreover, the most efficient treatment in reducing damping-off and root-rot severity and increasing each of plant height, number of pods/ plant and average weight of green pods (g) / plant was the combination with Bion and B. megaterium. Treating pea seeds with the tested Bacillus strains and the CRIs resulted in increasing of the total phenols in the roots pea plants compared with the plants of untreated seeds. The study recommends treatment of pea seeds in the mixture of Bion and B. megaterium to protect the roots and seedlings and improve the plant characteristics.