Photosynthesis in a sub-Antarctic shore-zone lichen

TY - JOUR

T1 - Photosynthesis in a sub-Antarctic shore-zone lichen

AU - Smith, V.

AU - Gremmen, N.J.M.

N1 - Reporting year: 2001 Metis note: 2710; CEME; PGPE; file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs2001/Smith_ea_2710.pdf

PY - 2001

Y1 - 2001

N2 - Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net photosynthesis were 225-346% (ash free, dry mass). Net CO2 exchange was dominated by a strong temperature dependence of respiration rate. Net photosynthetic rate responded sharply to increasing PPFD and saturated below 300 µmol m2 s1, but electron transport rate (ETR) increased up to approx. 900 µmol m2 s1 PPFD suggesting that gross photosynthesis responded to light to this level. Nonphotochemical fluorescence quenching increased rapidly with PPFD up to approx. Salinity did not significantly influence CO2 assimilation rate; however, NH4NO3 significantly depressed net photosynthesis rate at all salinities except 100% seawater. ETR and dark respiration rate were increased by NH4NO3. The response of T. complicatulum to light and temperature enables high rates of CO2 assimilation under the island's microclimatic regime; if sufficiently hydrated, the lichen would exhibit near maximal photosynthesis rates for approx. 75% of the photoperiod over the year. [KEYWORDS: Turgidiusculum complicatulum; Mastodia tesselata; lichen; photosynthesis;sub-Antarctic; salinity moisture; temperature; light; inorganic nitrogen; chlorophyll fluorescence]

AB - Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net photosynthesis were 225-346% (ash free, dry mass). Net CO2 exchange was dominated by a strong temperature dependence of respiration rate. Net photosynthetic rate responded sharply to increasing PPFD and saturated below 300 µmol m2 s1, but electron transport rate (ETR) increased up to approx. 900 µmol m2 s1 PPFD suggesting that gross photosynthesis responded to light to this level. Nonphotochemical fluorescence quenching increased rapidly with PPFD up to approx. Salinity did not significantly influence CO2 assimilation rate; however, NH4NO3 significantly depressed net photosynthesis rate at all salinities except 100% seawater. ETR and dark respiration rate were increased by NH4NO3. The response of T. complicatulum to light and temperature enables high rates of CO2 assimilation under the island's microclimatic regime; if sufficiently hydrated, the lichen would exhibit near maximal photosynthesis rates for approx. 75% of the photoperiod over the year. [KEYWORDS: Turgidiusculum complicatulum; Mastodia tesselata; lichen; photosynthesis;sub-Antarctic; salinity moisture; temperature; light; inorganic nitrogen; chlorophyll fluorescence]

U2 - 10.1046/j.1469-8137.2001.00025.x

DO - 10.1046/j.1469-8137.2001.00025.x

M3 - Article

SN - 0028-646X

VL - 149

SP - 291

EP - 299

JO - New Phytologist

JF - New Phytologist

IS - 2

ER -