Effect of rice cultivar on CH4 production potential of rice soil and CH4 emission in a pot experiment.

Methane production potential (MPP) of rice soil, defined here as the mean value of methane production rate (MP-R) of rice soil over a given period in which the substrate for methanogenesis is presumably depleted, significantly affects CH₄ emission to the atmosphere. To expand our understanding of how MPP was affected in soils grown with different rice cultivars ( Yanxuan, 72031 and 9516) and its consequence on CH₄ emission, the changing pattern of MP-R was elucidated in the present study. On an entire rice growing scale, the MPP of planted soil was significantly higher than that of unplanted soil, and the MPP of 72031 rice soil was 9.42 µg CH₄ kg _(d.w.s)⁻¹ h⁻¹, significantly lower than Yanxuan (18.2 µg CH₄ kg _(d.w.s)⁻¹ h⁻¹) and 9516 rice soils (17.7 µg CH₄ kg _(d.w.s)⁻¹ h⁻¹). Yanxuan and 9516 soils had a similar MP-R changing pattern, which was distinct from 72031 soil. On a temporal scale of the representative rice growing stages (i.e. early tillering, late tillering, panicle initiation, ripening and harvesting stages), the MPP of rice soils varied widely among rice cultivars, and MPP coincided well with CH₄ emission regardless of rice cultivars. No clear pattern was observed in soil redox potential (soil E _h), or in above-ground biomass of rice cultivars to MPP and CH₄ emission. [ABSTRACT FROM AUTHOR]