Impact of root exudates of different cultivars and plant development stages of rice (Oryza sativa L.) on methane production in a paddy soil

• Published in: Plant and soil Vol. 230; no. 1; pp. 77 - 86
• Main Authors: Aulakh, Milkha S., Wassmann, Reiner, Bueno, C., Rennenberg, Heinz
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01.03.2001; Springer; Springer Nature B.V
• Subjects: Acid soils; Adaptation to environment and cultivation conditions; Agricultural soils; Agronomy. Soil science and plant productions; Anaerobic conditions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Clay soils; Cultivars; Emissions; flooded conditions; Fundamental and applied biological sciences. Psychology; genetic variation; Genetics and breeding of economic plants; Methane; Methane production; Organic acids; organic acids and salts; Organic matter; Oryza sativa; paddy soils; Philippines; Physics, chemistry, biochemistry and biology of agricultural and forest soils; plant development; Plant roots; Plants; Rice; Rice fields; Rice soils; Root exudates; soil air; Soil science; Soil strength; Soils; Varietal selection. Specialized plant breeding, plant breeding aims; Asia; Philippine Islands; Philippines; Methane; Monocotyledones; Gas emission; Exudate; PADDY SOIL; Variety trial; Cultivated soil; Submersion; High yielding variety; FLOODED RICE; Cereal crop; Organic acids; Field experiment; Tropical soil; Oryza sativa; Gramineae; Greenhouse gas; Angiospermae; Methanogenesis; Carbohydrate; Paddy field; Developmental stage; Excretion; Hydrocarbon; Root; Tropical crop; Varietal selection; Experimental study; Biological activity; Agroecosystem; Carbon cycle; Biogeochemistry; Genetic improvement; Spermatophyta; Exudation; Soil plant relation; Environmental protection
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/a:1004817212321

The impact of root exudates, collected from five rice cultivars, on methane (CH₄) production was studied in a paddy soil under anaerobic conditions. Root exudates of the cultivars Dular, IR72 and IR65598 collected at four growth stages and of B40 and IR65600 collected at two growth stages showed that (a) CH₄ production was commenced rapidly within 2 h upon exúdate addition and reached a maximum within a day of addition, and (b) 7-d incubation periods were sufficient to study exudate-induced CH₄ production potentials. Among different cultivars, high C releases from roots, increased the methanogenic source strength of the soil, which finally controlled CH₄ production. The relationship of the amount of CH₄ produced was stronger for the amount of total organic C (r = 0.920) than for the amount of organic acids (r = 0.868) added through exudates. Apparently, CH₄ production and CH₄ emission are more closely related to the release pattern of root exudate-C than to its individual components. The proportion of exudate-C converted to CH₄ ranged between 61 and 83% and remained unaffected by cultivars and growth stages suggesting that the majority of exudate-C served as a methanogenic substrate in the anoxic rice soils. These observations indicate that the use of high-yielding cultivars with lowest excretion (for example IR65598, IR65600) would result in lowest exudate-induced CH₄ production. Therefore, cultivar choice could greatly influence regional and global CH₄ emissions and screening/selection of exiting rice cultivars, and/or breeding new cultivars with low exudation rates could offer an important methane mitigation option as long as yields are not compromised.