Non-destructive acetylene reduction assay of nitrogen fixation applied to white clover plants growing in soil

摘要

Abstract A technique for the acetylene reduction assay of nitrogen fixation was developed in which intact, undisturbed white clover (Trifolium repens plants growing in soil or sand were placed in an acetylene/air atmosphere and the production of ethylene measured. After a short initiation period ethylene production in this test was as rapid as in tests in which root systems were fully exposed to acetylene, and continued with little decrease in rate for at least 30 hr. Successive tests, each lasting 24 hr, were made on pots of white clover over a period of 2 months. These showed a close relationship between ethylene production and nitrogen fixation (r ?0.976), with approximately 3.7 moles of ethylene produced per mole of nitrogen fixed. The tests did not seriously affect subsequent growth of the plants, so individual samples could be tested repeatedly.