Endophytic Plant Growth-Promoting Rhizobacteria Promote Dendrobium Orchid Growth

Dendrobium orchid is one of the major export products of Thailand. Endophytic bacteria inhabiting the roots have the ability to promote plant growth. They could be used to replace the chemical fertiliser. In this study, 42 bacterial isolates were isolated from the orchid roots and were screened for plant growth- promoting rhizobacteria (PGPR). We selected six isolates that exhibited plant growth promotion (PGP) abilities, including siderophores, IAA, and ACC deaminase production, phosphate-solubilisation, and nitrogen-fixation. The 16S rRNA gene sequencing identified these isolates as Enterobacter sp. and Bacillus sp. with a prominence of Bacillus halotolerans. All six isolates were confirmed to inhabit the orchid roots and were inoculated into the orchid hybrid (D. anosmum × D. parishii) seedlings. We found that B. halotolerans O-SWU-17 enhanced orchid seedling growth in vivo. Thus, B. halotolerans O-SWU- 17 has great potential as a biofertiliser in enhancing orchid production.