Characterization of Endophytic-rhizobacteria from Areca Nut Rhizosphere to Dissolve Phosphates, Nitrogen Fixation of IAA Hormone Synthesis

Gusti Ayu Kade Sutariati, Nini Mila Rahni, Abdul Madiki, La Mudi, I. Made Guyasa and Zahrima

Background and Objective: The ability of rhizobacteria to dissolve phosphate, fix nitrogen and synthesize growth hormones has a direct or indirect effect on increasing the plant growth including seed growth. The rhizobacteria which are inoculated in seeds through biopriming are proven to increase seed growth. The study aims to obtain the potential indigenous rhizobacteria from areca nut plant rhizosphere on marginal soil of Southeast Sulawesi. Materials and Methods: Research was arranged in a completely randomized design (CRD) consisting of 10 isolates. The isolates were evaluated their ability to solubilize phosphate, fix nitrogen and synthesize IAA growth hormone. Also evaluated the effect of these isolates in increasing the root length of rice seedlings. Before tested, rice seeds were treated with rhizobacterium isolates of endo-rhizobacteria and germinated using standard germination procedures. Root length was observed on the 7th day after planting. At the same time all isolates were evaluated for their ability to solubilize phosphate, fix N and synthesize IAA. Results: The results showed that seed treatment using endo-rhizobacteria significantly increased the root length of treated rice seeds (percentage increase compared to untreated seeds at root length up to 140%). All rhizobacteria isolates tested were able to solubilize phosphate, fix N and synthesize IAA. Although all of the rhizobacteria synthesized IAA, growth promoting effects of the rhizobacteria may not only be due to the synthesized growth regulator. Other factors may have involved in the positive effects of the endo-rhizobacteria on rice seed germination. Conclusion: The endophytic and rhizobacterial dominant from the areca nut rhizosphere are the Pseudomonas spp. and the Bacillus spp. and have ability to solubilize phosphate, fix nitrogen and synthesize IAA and also could increase rice seed growth.

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