Ethylene production was monitored in 12 desert soils. In all but two soils with high organic matter content, C2H4 production was low. Statistical analysis showed a good correlation between organic matter content and C2H4, production. Minimum levels of C2H4 were observed in saline and sodic soils. Addition of l-methionine to soil significantly increased C2H4 formation, indicating its possible role as a precursor for C2H4. Addition of salt to the high C2H4-producing soils suppressed C2H4 production most probably because of a direct effect on C2H4-producing microorganisms through toxic salt levels, high osmotic pressure, increased pH or a combination of these factors. Leaching of four saline soils and subsequent incubation resulted in significant increases in C2H4 in two soils. Ethylene producers, previously inhibited by salinity, were probably reactivated when the salts were removed. A Fusarium isolated from the high C2H4-producing soil, produced the most C2H4 in pure culture followed by isolates belonging to the genera Aspergillus, Penicillium, Curvularia and Rhizopus. A sterilized saline soil produced significant C2H4 when inoculated with spores of Mucor hiemalis or the Fusarium isolate, indicating an originally low population of C2H4-producing organisms in the saline soil. The two high organic matter soils when sterilized and similarly inoculated produced only a fraction of the C2H4 produced in non-sterilized samples, indicating the involvement of a number of species in the production of C2H4 in these soils.
ASJC Scopus subject areas
- Soil Science