Temporal variation in methanogenic community structure and methane production potential of tropical rice ecosystem

Temporal variations in diversity of methanogenic community and CH4 production potential were analyzed in an Indian tropical rice ecosystem. Laboratory incubations showed that methane production varied from 20.86 to 134.11 μg CH4 g−1 d.w.s. during the two consecutive years, 2009 and 2010. CH4 production potential was high at the flowering stage of the rice crop followed by ripening, tillering, post-harvest and pre-plantation stage. Phylogenetic analysis of 16S rRNA genes of methanogenic community indicated that flowering and ripening stages comprised of Methanomicrobiaceae, Methanosarcinaceae, Methanosaetaceae and RC I methanogenic groups, while only the members of Methanomicrobiaceae and RC I were present in the remaining stages. Further, the dominance of RC I was observed in all stages. This study demonstrates that flowering and ripening stages of rice crop offer relatively favorable ecological niche for methanogenic community. The overall analyses suggest that the temporal change in diversity of methanogens regulates CH4 production potential in rice field soils.

► This study explores variation in changes in methanogenic community structure over the phenological cycle of a tropical rice crop i.e., from pre-plantation to crop harvest. ► Variations in CH4 production potential were associated with shifts in methanogenic community structure. ► This study demonstrates that flowering and ripening stages of rice crop offer relatively favorable ecological niche for methanogenic community. ► This study will provide baseline data on methanogenic community particularly for country like India where such information is almost scarce till now.