Altitudinal trends in needle chlorophyll content and chlorophyll fluorescence of Norway spruce (Picea abies Karst.) seedlings exposed to increased ultraviolet-b radiation

The main purpose of this study was to determine the relation between the altitude of Norway spruce seed origin and seedling response enhanced UV-B irradiation. There were threeUV-B treatments: high UV-B with a dose of 22.76 kJ m^-2 d^-1 UV-B[BE] (biologically effective dose), low UV-B-5.69kJ m^-2 d^-1 UV-B[BE] and control>> ~ 0 kJ m^-2 d^-1 UV-B[BE]. The plants were exposed to enhanced UV-B during 120 days in the greenhouse. Needle chlorophyll content and chlorophyll fluorescence parameters were investigated. The chlorophyll content in irradiated needles was lower relative to control after 30 days of exposure to UV-B, but it was higher after 70 days. All the measured chlorophyll fluorescence parameters including relative vitality indexes were reduced for needles exposed to an increased UV-B radiation. Generally, the needles' chlorophyll content was increased and chlorophyll fluorescence parameters were decreased with altitude of seed origin. The results suggest that the acclimation to higher altitudes may also consist of an increased chlorophyll production. The alterations in chlorophyll concentration among the seedlings originating from different altitudes showed that response of Norway spruce to an enhanced UV-B irradiation depends on the altitude of origin.