Functional Microbial Population on Oil Palm Rhizosphere in Riau Peatlands

Populasi Mikrob Fungsional pada Rhizosfer Kelapa Sawit di Lahan Gambut Riau

Abstract

Oil palm growth in peatland may influence the presence of microbial populations. Root exudate is one of the organic compounds that is released by oil palm roots in the rhizosphere area where it can be used as a nutrient for microbes to survive in peatland. The study was conducted to study functional microbial population in the rhizosphere area of oil palm plantation aged <6, 9−15, and >15 years in Riau peatlands. The highest microbial populations were found in oil palm plantation aged <6 years at peat thicknesses of <3 and >3 m, which was respectively 10.3 x 10⁶ and 5.7 x 10⁶ CFU g^-1. The highest cellulolytic microbial population was found in oil palm plantation aged <6 years at peat thicknesses of <3 and >3m, which was respectively 17.4 x 10⁴ and 11.4 x 10⁴ CFU g^-1. The highest Azotobacter population was found in oil palm plantation aged >15 years at peat thicknesses of <3 and >3m, which was respectively 9.4 x 10⁵ and 12.5 x 10⁵ CFU g^-1. The highest phosphate solubilizing microbial population was found in oil palm plantation aged <6 years at peat thicknesses of <3 and >3m, which was respectively 11.4 x 10⁴ and 13.2 x 10⁴ CFU g^-1. The highest fungal population was found in oil palm plantation aged <6 years at peat thicknesses of <3 m and >3 m, which was respectively 11.4 x 10⁴ CFU g^-1 and 17.3 x 10⁴ CFU g^-1. The highest white-rot fungal population was found in oil palm plantation aged 9−15 years at peat thicknesses of <3 m and >3 m, which was respectively 8.7 x 10³ CFU g^-1 and 9.4 x 10³ CFU g^-1. In conclusion, the highest microbial population was dominantly found in oil palm plantation aged <6 years.

Keywords: Microbial populations, oil palm plantation, peat thickness, rhizosphere area