Ethylene turn-over in soil, litter and sediment

Turn-over (i.e. production and consumption) of ethylene was examined in contrasting soil types to evaluate the effect of environmental changes on C2H4 dynamics. Three general responses to batch incubation with C2H4 (generally 12–16 μl l−1) were observed: (i) arable soil and lake sediment required prolonged acclimation (1–4 weeks) for C2H4 consumption and showed no C2H4 production; (ii) coniferous and deciduous forest soil showed an inherent capacity for C2H4 consumption (21–85 pmol C2H4 g−1 dry wt h−1) and a subsequent C2H4 production (4–26 pmol C2H4 g−1 dry wt h−1), which coincided with a depletion of O2 to below ∼1%; (iii) coniferous litter samples showed a slight C2H4 consumption (0–30 pmol C2H4 g−1 dry wt h−1) followed by a large C2H4 production (32–120 pmol C2H4 g−1 dry wt h−1), again coinciding with depletion of the O2 pool. The results for forest samples indicated that C2H4 was produced and consumed simultaneously under aerobic conditions, while it was only produced under sub-oxic conditions. Similar patterns of C2H4 turn-over were found in samples collected in different years and both C2H4-consuming and -producing microorganisms survived during storage at 2°C for 22 months. Notably in coniferous soil, changes in C2H4 dynamics apparently could have the potential to adversely influence plant growth.