Environmental‐physiological Interactions in Lichens

Abstract

SUMMARYThe nitrogenase activity in Peltigera polydactyla was examined during varying periods of darkness and after re-illumination. There was an immediate decrease in activity of about 50% when the lichen was darkened, followed by a progressive further decrease of activity with time. Recovery to the original level of activity on re-illumination showed an increasing lag as the dark period was extended. The effect of an external carbon source on nitrogenase activity was also examined and very large increases in activity were induced in the light, by both 2% glucose and mannitol. The decrease during a dark period was, however, still very marked.

Terrestrial cryptogams of pinyon-juniper woodlands in the Southwestern United States : a review /

“…Other considerations particularly relevant to nitrogen measurements in cryptogams have been reported. Extended exposure to acetylene results in abnormally high rates of acetylene reduction in Peltigera polydactyla (MacFarlane et al 1976) and…”

Nitrogen Fixation on a Tropical Volcano, La Soufrière: Nitrogen Fixation By the Pioneer Lichen Dictyonema Glabratum

“…Nitrogenase activity was measured using the acetylene reduction technique as described in detail elsewhere (Fritz-Sheridan 1987). Lichen material was discarded after each incubation period to avoid acetylene pretreatment stimulation (Macfarlane et al 1976). Photon flux density is reported as |imol m" 2 s" 1 PAR (X400-700nm, General Electric, cosine corrected meter).…”

Nitrogen Fixation on the Tropical Volcano, La Soufrière (Guadeloupe): Nitrogen Fixation, Photosynthesis and Respiration During the Prevailing Cloud/Shroud Climate By Stereocaulon Virgatum

“…9). Dark nitrogenase activity, driven by carbohydrate pools, may continue for long periods in the absence of light in some lichens (Hitch & Stewart 1973) or may cease abruptly when transferred to darkness as was reported for Peltigera polydactyla (MacFarlane et al 1976).…”