Chili is one of the horticultural commodities that still requires serious handling, especially in the context of increasing production both in quality and quantity. Seed treatment using biological seed treatment agents is an alternative as a substitute for synthetic chemicals in seed treatment. This study aims to determine the inhibitory power of rhizobacteria in the growth of colonies of pathogens carried by chili seeds in vitro and the mechanism of action of rhizobacteria to inhibit the growth of Phytophthora colonies in chili. The research was carried out at the Seed Science and Technology Laboratory, Laboratory of Plant Disease, Biology Laboratory, Teacher Training and Education Faculty, Syiah Kuala University, Inter-University Central Laboratory and Bacteriology Laboratory of IPB Bogor from July 2014 to March 2015. Conducted isolation of carrying pathogens of chili seeds namely pathogenic fungi P. Capsi and isolation of rhizobacteria of bio-control agent candidates and rhizobacterial agents promote plant growth candidates. The results showed that the results of detection, exploration and isolation of rhizobacteria from the root system of healthy chili plants obtained 154 rhizobacterial isolates. Antagonistic test results obtained one rhizobacterial isolate, namely Rbks-5 isolate has a very high inhibitory power on the growth of pathogenic colonies test S.rolfsii dan Phytium sp. While rhizobacteria Rbks-6 isolates and Rbks-7 isolates have very high inhibitory power on the pathogen S. rolfsii and P. capsici. Rhizobacterial isolates which produced the highest IAA were Rbkb-2 isolates, followed by 3 isolates capable of producing IAA growth regulators namely Rbkp-4, Rbks-2, Rbks-5 rhizobacterial isolates.
