ISOLATION OF HALOTOLELANT RHIZOBACTERIA FROM SALINE SOIL AND THEIR EFFECT ON RICE SEED GERMINATIONPORNRAPEE SARIN, SOPHON BOONLUE AND NUNTAVUN RIDDECH
Halotolerant rhizobacteria were isolated from rice rhizosphere samples in saline soil in Khon Kaen and Mahasarakam provinces, Thailand. Among 3 isolates, P8, N15 and I2.1, the isolates P8 and N15 were able to fix nitrogen from the air and to solubilize tri-calcium phosphate on the National Botanical Research Institutes phosphate growth medium with the solubilization index of 2.42 and 2.93, respectively. The isolate I2.1 produced indole-3-acetic acid (IAA). Among 3 isolates, N15 showed the highest cellulose degradation activity on the carboxymethyl cellulose agar (CMC agar) plate with the maximum hydrolysis capacity value of 5.49. The isolate I2.1 showed the potential of inhibition the growth of Pyricularia oryzae, a fungal pathogen of rice blast disease with the percent inhibition of radial growth (%PIRG) of 42.4%. Mixculture of rhizobacterial isolates P8, N15 and I2.1 were used for stimulating rice seed germination in various concentrations of NaCl solution and the germination index of rice seed was greater than 80% in 5-10 dS/m of NaCl solution. Using 16S rDNA sequence analysis, three halotolerant rhizobacria isolates, I2.1, P8 and N15, were identified as Pseudomonas azotoformans, Enterobacter aerogenes and Bacillus tequilensis, respectively.
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