Synergy between bio-control agents to trigger the defensive responses against Rhizoctonia root rot and enhance the growth, yield, and physiological and anatomical traits of pea plants

Abstract

Rhizoctonia solani (Rs) is the fungus that causes the primary and deadly disease that attacks pea plants throughout the cool growing season. It causes seed rot, damping off, and pea root rot diseases. The current study used arbuscular mycorrhizal fungi; Rhizoglomus clarum, Gigaspora margarita, Rhizophagus irregularis and Funneliformis mosseae (AMF), Pseudomonas fluorescens HE21 (Pf), and Trichoderma harzianum HL9 (TH) singly or in combination to suppress Rhizoctonia root rot of pea in a greenhouse. Using the in vitro dual culture assay, TH and Pf inhibited the radial growth of the Rs by 73.3 and 60.0%, respectively. The results of greenhouse experiments showed that all treatments significantly decreased the percentages of pre- and post-emergence damping while significantly increasing the number of surviving plants, particularly in the dual and triple combination treatments. Furthermore, all treatments improved yield and seed quality in addition to plant growth, total phenol content and antioxidant enzyme activity. There were also noted modifications to the treated plants’ anatomical, physiological, and distinctive features. The synergistic triple treatment consisting of M, TH, and Pf achieved the maximum reduction of disease severity (78.5%) compared to the untreated control treatment. As a result of the synergistic triple treatment due to their effectiveness and eco-safety, we recommend using the synergistic triple by M + Pf + TH to manage the root rot disease in peas caused by Rs and to enhance the crop’s growth, yield, and seed quality.