Organic Acid-mediated Modulation of Panicle Architecture and Grain Quality in Oryza sativa L. under Sheath Blight Disease

Sheath blight in rice is caused by a necrotrophic pathogen (Rhizoctonia solani) which poses significant threats to rice productivity by triggering physiological disruptions that impair its reproductive yield and grain quality. The present investigation examines the structural and metabolic effects of two organic acids, benzoic acid and oxalic acid, individually and in combination, on yield-associated traits and grain quality in rice subjected to R. solani infection. Eight treatments were evaluated: untreated control (Control), pathogen-infected control (Rsolani), benzoic acid (OA1), oxalic acid (OA2), benzoic acid with oxalic acid (OA1OA2), benzoic acid treatment with pathogen infection (OA1RS), oxalic acid treatment with pathogen infection (OA2RS), and combined benzoic acid and oxalic acid treatment with pathogen infection (OA1OA2RS). The responses of rice plants were assessed using test weight, panicle number per plant, panicle weight, primary and secondary branches per panicle, grain number per panicle, and total grain starch content (%). The pathogen-infected plants exhibited an overall reduction in yield-associated traits compared to the control, indicating the adverse effect of R. solani infection on reproductive development and grain formation. Application of benzoic acid and oxalic acid modified the response of rice to pathogen stress and alleviated disease effects to varying degrees. The treatment with benzoic acid and the combination of organic acids exhibited better overall performance individually as well as under R. solani infection. Improvements in panicle development, grain number, panicle architecture, and starch accumulation in treated rice plants suggest that organic acid application may mitigate physiological consequences of R. solani infection. The observations suggest the possible activation of host defence mechanisms, modification of metabolism, enhanced antioxidant capacity, and maintenance of source and sink relationships during reproductive development. The findings indicate that benzoic acid derivative, alone or combined with oxalic acid, has potential as a component of an integrated approach for maintaining rice productivity under sheath blight disease stress. Further studies are required involving host-pathogen interactions and defence-associated metabolism to establish the mechanisms underlying the observed responses.