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Start Over Creator Solhaug, K. A.

1. Irradiance prior to and during desiccation improves the tolerance to excess irradiance in the desiccated state of the old forest lichen Lobaria pulmonaria

Creator:
Štepigová, J., Gauslaa, Y., Cempírková-Vráblíková, H., and Solhaug, K. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, photosynthetic quenching, photoinhibition, and xanthophyll cycle
Language:
Multiple languages
Description:
Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 µmol m-2 s-1) or medium irradiance (MI, 200 µmol m-2 s-1) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these dry lichens were exposed to high irradiance (HI, 1 000 µmol m-2 s-1) for 60 h. After this HI treatment, the maximal photochemical quantum yield (FV/FM) and the de-epoxidation state of xanthophyll cycle pigments (DEPS) were highest in thalli preconditioned to MI. Hence irradiance in the last hydrated period before sampling is significant for the physiological state of lichens. A standardized irradiance pre-treatment before start of experiments is recommended. and J. Štepigová ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Seasonal variation of photoinhibition of photosynthesis in bark from Populus tremula L.

Creator:
Solhaug, K. A. and Haugen, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence induction, irradiance, oxygen evolution, phellem, photosystem 2, poplar, quantum yyield, seasonal course, and tree age
Language:
Multiple languages
Description:
In the bark of Populus tremula L. photochemical efficiency of photosystem 2 (PS2) determined as Fv/Fm decreased during winter. The strongest reduction was found after cold periods. The degree of reduction depended on irradiance since the lowest levels of Fv/Fm were found on the sun-exposed side of the stem and below thin phellem. Therefore, photoinhibition was partly responsible for the reduction in Fv/Fm. The photochemical efficiency of PS2 recovered in late April about a month before the trees got leaves. In the laboratory, Fv/Fm recovered within about a week under low irradiance at 20 °C. Rapid recovery of photochemical efficiency of PS2 in the bark may be important to reduce respiratory loss of CO2 from the stem before the trees get leaves. and K. A. Solhaug, J. Haugen.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public