Ethylene Accumulation in Soil in Response to Organic Amendments
- Muhammad Arshad and
- W. T. Frankenberger
Dep. of Soil and Environmental Sciences, Univ. of California, Riverside, CA 92521
One of the major factors affecting ethylene (C2H4) accumulation in soil is the availability of organic substrates. Various organic compounds were screened for their stimulatory effect on C2H4 accumulation in soil. Since L-methionine (L-met), a sole precursor of C2H4 synthesis in plants, is also an excellent precursor for microbial biosynthesis of C2H4, all the compounds tested were added on a C-equivalent basis with respect to 1 g L-met kg−1 soil. Incubation was carried out under ambient conditions (24 ± 3 °C) for 14 d and the soil was maintained at field capacity (−33 kPa). Among the 63 compounds tested, the majority of amino acids, organic acids, carbohydrates, proteins, alcohols, and met analogs promoted C2H4 generation to a greater degree than did the unamended soil. Use of 1-aminocyclopropane-1-carboxylic acid (acc) enhanced C2H4 synthesis much more than any other treatment (2400-fold over the unamended nonsterile control). Of the five vitamins tested, inositol was the most effective in promoting C2H4 production. L-Ethionine (L-eth) was an excellent precursor among the five met analogs. Nonbiological production of C2H4 was observed only upon treatment with L-met, L-cysteine, acc, ethanol, and L-eth, which were 7.9, 19.0, 3.0, and 4.2% and 2.1-fold, respectively, of the total C2H4 detected under nonsterile amended conditions. Since the majority of these compounds are excreted by plant roots, the rhizosphere may be an active site for C2H4 generation.
Contribution from the Dep. of Soil and Environmental Sciences, Univ. of California.
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