Cultivar variation in methane efflux from tropical rice

Abstract

Wide variation in CH₄ flux was noticed among the ten rice cultivars grown under uniform field conditions. Cumulative CH₄ flux ranged from 4.61 g m^-2 to 20.25 g m^-2. The rice cultivars could be ranked into three groups based on their CH₄ flux potential. Rice cultivars could also be arranged based on their peak CH₄ emission occurring either at vegetative, reproductive or at both growth stages. Of the several variables studied (root region redox potential, above- and underground biomass, grain and straw yield, duration of the crop, percent area occupied by the air space and root oxidase activity), only oxidase activity of the root tip exhibited a significant (negative) correlation with CH₄ flux indicating an indirect effect of root oxidation potential on CH₄ flux. Data presented in this study, demonstrate inherent variation in CH₄ flux among different rice cultivars that can be used for developing future mitigation options.