Enhanced Expression of Defense Enzymes in Groundnut (Arachis Hypogaea) Plants Through the Combined Application of Marine Macroalgae and Bioagents to Combat Sclerotium Rolfsii.

Groundnut, Arachis hypogaea L., is a leguminous crop widely cultivated for its edible oil seeds. It faces significant challenges from soil-borne diseases, including Sclerotium rolfsii Sacc., which severely affect groundnut production and productivity. Biological control methods offer broader treatment alternatives than traditional chemical approaches. The present study investigated the activation of defense enzymes such as peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) in groundnut plants under pot culture conditions. The plants were treated with different marine macroalgae and bioagent combinations, where inoculation with S. rolfsii was challenged. Among the nine treatments, T4 {seed treatment [ST] by Sargassum wightii extract at 2% + soil application (SA) of S. wightii at 100 g/pot + ST by Trichoderma asperellum (Tr-3) at 4 g/kg of seeds + SA with T. asperellum (Tr-3) at 50 g/pot} concentrations gave the maximum increased activities of PO (1.40 changes in absorbance min/g of leaf tissue), PPO (2.03 changes in absorbance min/g of leaf tissue), and PAL (9.56 changes in absorbance min/g of leaf tissue). In contrast, the inoculated control exhibited minimal activity of these enzymes. The increased enzyme activities were recorded until 24 days after sowing, and a gradual decrease was observed afterward. The present study showed that marine macroalgae and bioagents could enhance defense enzyme activity in groundnut plants and significantly prevent the disease caused by S. rolfsii. [ABSTRACT FROM AUTHOR]