Impact of gas transport through rice cultivars on methane emission from rice paddy fields

Abstract

Two Italian rice {Oryza sativa var. japonica) cultivars, Lido and Roma, were tested in the field tor methane production, oxidation and emission. In two consecutive years, fields planted with the rice eultivar Lido showed methane emissions l'\-'i\% lower than fields planted with the eultivar Roma. This differenee was observed irrespective of fertilizer treatment. In eontrast to methane emissions, differenees in methane production or oxidation 'were not observed between fields planted with the two eultivars. Plant-mediated transport of methane from the sediment to the atmosphere was the dominating pathway of methane emission. During the entire vegetation period, the contribution of this pathway to total methane emission amounted to c. 90%, whereas the eontribution of gas bubble release and of diffusion through the water eolunin to total methane emission 'was of minor significance. Results obtained from transport studies of tracer gas through the aerenehyma system of riee plants demonstrated that the root-shoot transition zone is the main site of resistance to plant-mediated gas exchange between the soil and tbe atmosphere. The eultivar Lido, showing relatively low methane emissions in the field, bad a signifieantly lower gas transport eapaeity through the aerenehyma system than the eultivar Roma. Thus, tbe observed differenees in methane emissions in the field between tbe eultivars Lido and Roma ean be explained by different gas transport eapaeities. Apparently, tbese differenees in gas transport eapaeities are a eonsequenee of differenees in morphology of the aerenebyma systems, espeeially in the root-slioot transition zone. It is, therefore, eoneluded that identifieation and use of high-yielding riee enltivars whieh have a low gas transport eapaeity represent an eeonomieally feasible, environmentally sound and promising approaeb to mitigating methane eniissons from riee paddy fields.

Root oxygen loss from Raphia taedigera palms mediates greenhouse gas emissions in lowland neotropical peatlands

“…Indeed, the decline in CH 4 emissions at the later stages of rice growth (Fig. 3e) might be attributed to the gradual increase of CH 4 oxidation and inhibition of methanogenesis due to radial oxygen loss by rice root system (De Bont et al 1978;Gerard and Chanton 1993;King 1996); or by the increasing contribution of plant mediated CH 4 emissions through rice aerenchyma, which we could not account for with our methodological approach (Butterbach-Bahl et al 1997). Overall, the dissolved O 2 concentration in the pore-water of the surface peat was a strong driver of both CH 4 and N 2 O emissions in situ, accounting for 40 and 20 % of the variance in fluxes for the two gases, respectively (Fig.…”

Atmospheric Methane: Trends and Impacts

“…Emissions are also determined by the number of crops per year and the total area under cultivation, which is a function of the demand for rice, and the amount of rice produced per hectare, known as the 'yield'. Practices such as occasional draining of the fields, the addition of oxidents or other mineral fertilizers, and selection of low-CH 4 cultivars have been found to reduce emissions by approximately 40-55%, 20-70% and up to 60%, respectively (EPA, 1994;Neue et al, 1997;Sigren et al, 1997;Yagi et al, 1997;Butterbachbahl et al, 1997;Cole et al, 1997;Mitra et al, 1999). Alternatively, the addition of organic fertilizers has the potential to increase emissions by over 50% relative to non-organic fertilizers (e.g., Buendia et al, 1997;Denier van der Gon & Neue, 1995;Yagi et al, 1997).…”

Methane Emissions among Hybrid Rice Cultivars in the MidSouthern United States

“…While the implementation of certain mitigation options by producers may be restricted due to required changes in management practices and equipment or the possibility of yield reductions, the selection of low-emitting cultivars can be implemented without major changes in crop management while maintaining grain yields. Studies have indicated that about 90% of CH 4 emissions from rice fields occur by plant-mediated transport through the aerenchyma tissues of rice plants [16,19,23,24]. Due to the strong influence of rice plants themselves on CH 4 emissions from the system, innate physiological differences between cultivars may lead to differences in CH 4 transport capacities [23], differences in biomass accumulation [25] and root exudation [26,27,28], or differences in microbial populations in the rhizpsphere [29].…”

“…Studies have indicated that about 90% of CH 4 emissions from rice fields occur by plant-mediated transport through the aerenchyma tissues of rice plants [16,19,23,24]. Due to the strong influence of rice plants themselves on CH 4 emissions from the system, innate physiological differences between cultivars may lead to differences in CH 4 transport capacities [23], differences in biomass accumulation [25] and root exudation [26,27,28], or differences in microbial populations in the rhizpsphere [29]. Many studies throughout rice-growing countries have reported differences in CH 4 emissions among rice cultivars; however, the complexity of the system and processes involved have led to differing results and, at this point, no single parameter has been identified to consistently explain differences in CH 4 emissions among cultivars.…”

“…This indicates a potential for increased CH 4 oxidation with hybrid cultivars, possibly due to greater methanotrophic activity in the rhizosphere of hybrid rice relative to pure-line cultivars. Butterbach-Bahl et al [23] attributed a difference in CH 4 fluxes among cultivars to differences in CH 4 transport capacity, as no differences were measured between potential CH 4 productions or oxidations among the cultivars. While several studies suggested differences in gas transport capacity or microbial community structure are the major influencing factors on differences in CH 4 fluxes among cultivars, additional studies have consistently suggested that differences in root exudation rates among cultivars are the primary factors that influence differences in CH 4 fluxes among cultivars [26,27,28,57,58].…”