Phytobeneficial and Plant Growth-promotion Properties of Silicon-solubilising Rhizobacteria on the Growth and Control of Rice Sheath Blight Disease

Abstract

Silicon is an important element for plant development and increases plant resistance against biotic and abiotic stresses. This study aimed to screen and evaluate potential silicon-solubilising rhizobacteria (SSR) with plant growth-promoting properties and inhibitory activities against rice sheath blight pathogen Rhizoctonia solani . Materials and Methods: The SSR were isolated from the disease-free rice field usi1ng magnesium trisilicate media. All isolates were screened in vitro for plant growth-promotion properties: The production of IAA and phosphate solubilisation. The inhibitory activities against R. solani : Dual culture testing, the production of volatile compound and hydrogen cyanide. The potential SSR isolates were identified using VITEK 2 system. Results: A total of 31 potential SSR were isolated from rice rhizosphere soil. Eight most potential SSR isolates were selected out of 31 SSR isolates obtained for further screening of the diffusible antibiotics and extracellular metabolites production against R. solani . Five SSR isolates (SSR2, SSR13, SSR24, SSR25 and SSR26) were selected as potential plant growth promoters with inhibitory effects against R. solani. Under greenhouse conditions, rice plants treated with SSR13, SSR24 and SSR26 showed significantly reduction in rice sheath blight disease incidence with 33.33, 16.67 and 20.00%, respectively, compared to the controls (56.67%). Isolate SSR24 showed a significantly lower disease susceptibility index of only 6%, compared to the control at 59%. Rice plants treated with SSR13 showed the highest plant growth in treatment without R. solani infection. Isolates SSR13 and SSR24 were identified as Serratia marcescens and Pseudomonas aeruginosa , respectively. Conclusion: Isolates Serratia marcescens (SSR13) and Pseudomonas aeruginosa (SSR24) show the most potential to be developed as rice plant growth promoters and also to control of rice sheath blight disease caused by R. solani . This study helps to reduce chemical application in rice sheath blight management toward sustainability in rice production system.