Diversity and Beneficial Activities of Native Microsymbiont in Lahar-Laden Zone of Gerona, Tarlac

Lahar-enrichment altered the soil resources of Gerona, Tarlac and shifted its utilization towards peanut production. However, lahar areas lack information on native microsymbiont which is vital to sustain legume productivity. A study was conducted to evaluate the genetic diversity and symbiotic potential of native bacteria in lahar-enriched soils of the municipality. A total of 45 bacterial strains were isolated from root nodules of peanut, grown in the study site. After authentication, 20 isolates were able to establish nodular infection which confirmed their symbiotic nature. These isolates were subjected to genetic profiling through Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) and 16S rRNA gene characterization. Upon ERIC-PCR analysis, 7 distinct DNA clusters were found, evidencing the divergence of molecular profiles among the isolates. Phylogeny of 16S rRNA genes revealed that the isolates belong to genus Rhizobium with close relationship to prominent species including R. miluonense, R. tropici, and Rhizobium sp. Meanwhile, symbiotic evaluation showed that inoculation of native strains RM15 and RT18 produced the highest nodule biomass, shoot yield, chlorophyll level and leaf N accumulation among all treatments. Consequently, RM15 and RT18 recorded symbiotic scores of 97.71 and 95.43% respectively. This is the first report on the remarkable diversity and symbiotic potential of native Rhizobium strains in lahar affected soils of the Philippines. The inclusion of these native strains in nutrient management could be explored to further increase peanut yields in the municipality.