Biocontrol and growth-promoting potential of Bacillus cereus TuR6 against rhizome rot disease in turmeric (Curcuma longa L.)

Rhizome rot disease caused by Fusarium solani severely limits turmeric (Curcuma longa L.) productivity. This study aimed to isolate endophytic bacterial strains from turmeric roots and screen them for plant growth-promoting (PGP) traits and antifungal activity. Among 10 isolates, strain TuR6, identified as Bacillus cereus (98.68% similarity, GenBank accession: PV565573), showed the highest IAA production (75.41 mg/L), strong phosphate solubilization (PSI 5.32), and positive siderophore, protease, and cellulase activities. TuR6 inhibited F. solani growth by 78.12% in vitro. In greenhouse trials, TuR6 significantly increased plant height (80.57 cm), rhizome yield (371 g/plant), and reduced disease incidence (17.7%). Field experiments confirmed its efficacy, with notable growth and disease suppression improvements under natural conditions. These results highlight B. cereus TuR6 as a potential bioinoculant for enhancing turmeric yield and managing rhizome rot sustainably.