Photosynthetic Active Pigments Changes in Norway Spruce (Picea abies) under the Different Acclimation Irradiation and Elevated CO2 Content

Photosynthetic active pigments content (chlorophylls and carotenoids) in Norway spruce (Picea abies) needles was measured by absorption spectroscopy. Norway spruce was exposed to low and high photosynthetic active radiation and ambient and elevated CO2 concentration. It was investigated that combination of low photosynthetic active radiation and elevated concentration of CO2 resulted in stimulation of chlorophylls and carotenoids production. Combination of high photosynthetic active radiation and elevated CO2 concentration led to overall chlorophylls and carotenoids content decrease. Moreover, specific leaf area trend could be used as a potentially reliable indicator of plant stress response. 1. Introduction Higher plants are permanently stressed by different kinds of natural and artificial factors. These stress factors could be drought, rapid temperature changes, diseases, herbicides, intraspecies and interspecies competition, insect, high salinity, low soil minerals content, and elevated carbon dioxide (CO2) concentrations. During the last 100 years CO2 concentration in atmosphere increased dramatically as a result of human activities. Actual CO2 concentration 350？μmol(CO2)·mol？1 is definitely not the fixed value and is going to increase in the future, Busch et al. [1]. It is expected that CO2 concentration will be two times higher than at the present (King et al. [2]). With respect to this expectation CO2 concentration influence on photosynthetic apparatus of the higher plants is a subject of interest for modern ecophysiology, Pittermann et al. [3], Gerhart et al. [4], and Whitehead [5]. 2. Experimental Methods One-year-old trees of Norway spruce (Picea abies) were used in this study. All plants were grown in soil substrate. Distilled water was used during the whole experiment. All plants were grown in growth chamber HB 1014 (Bio Line, Heraeus, Germany). Light regime in growth chamber was 8 hours of darkness and 16 hours of light. In the growth chamber there were stable conditions (humidity 65% and temperature 20°C). The first group of Norway spruce trees was adapted to high irradiation 1200？μmol·m？2·s？1 and atmospheric CO2 concentration 350？μmol(CO2)·mol？1 for 25 days. Thereafter irradiation remained the same, but CO2 concentration was increased up to 700？μmol(CO2)·mol？1. These conditions were kept for 11 days. The second group of Norway spruce trees was growing under the low irradiation 100？μmol·m？2·s？1 and atmospheric CO2 concentration for 25 days. After that irradiation remained the same, but CO2 concentration increased up to 700？μmol(CO2)·mol？1.