Evaluation of Native Isolates of Trichoderma against Fungal Pathogens of Rice, with Emphasis on Fusarium proliferatum

Abstract

Rice (Oryza sativa L.) is a major staple food crop Of Nepal; however, its productivity is constrained by fungal diseases, including blast (Pyricularia oryzae), sheath blight (Rhizoctonia solani), foot rot/seedling blight (Fusarium proliferatum). The present study aimed to evaluate the biocontrol potential of native Trichoderma isolates against major fungal pathogens of rice and to assess their effects on rice seedling vigor and suppression of F. proliferatum-induced seedling blight. Forty Trichoderma isolates were screened for antagonistic activity against F. proliferatum, P. oryzae, and R. solani and dual culture assays, followed by seed biopriming and screenhouse evaluation. Among the tested isolates, TL6-36B, TL2 50A, and TL4-81A completely inhibited the growth of all three
pathogens in the dual culture assay. TLI-2A also showed strong antagonistic activity and significantly improved seed germination and seedling growth. Based on their in vitro performance and growth-promoting effects, ten promising isolates were further evaluated in pot experiments under screenhouse conditions using rice cv. Khumal-4. The selected isolates significantly reduced the incidence and severity of seedling blight caused by F. proliferatum. In the seed treatment experiment, TLI-2A reduced disease severity by up to 74.55%, whereas TIA-81A reduced it by 68.41% compared with the pathogen-inoculated control. In soil treatment by drenching, TL4-81A and TLI 2A reduced disease severity by 68.95% and 67.89%, respectively. These isolates also improved seed germination and seedling vigor. Overall, native Trichoderma isolates, particularly TLI-2A and TL4-81 A, showed promising biocontrol activity against E proliferatum and may have potential for integrated management of rice seedling blight in Nepal.