INFLUENCE OF EXOGENOUS FACTORS ON THE ETHYLENE PRODUCTION BY LICHENS .1. INFLUENCE OF WATER-CONTENT AND WATER STATUS CONDITIONS ON ETHYLENEPRODUCTION

The influence of liquid water and water vapour on ethylene production has been examined in lichen species belonging to different genera (Cet raria, Peltigera), containing different photobionts (green algae, cyan obacteria) and colonizing distinct environments. Cetraria islandica, c haracterized by a broad ecological amplitude, was represented by two e cotypes. The results clearly show a correlation between ethylene produ ction and water content but there are intergeneric as well as intragen eric differences. The results obtained in this investigation are an in teresting parallel to the-observations on photosynthesis in lichens wi th green algae and cyanobacteria in connection with water vapour and l iquid water. There are indications that the photobionts in lichens are involved in ethylene production of the thallus.