Special issue in honour of Prof. Reto J. Strasser - Origin rather than mild drought stress influenced chlorophyll a fluorescence in contrasting silver fir (Abies alba Mill.) provenances

The performance of PSII photochemistry in five Central European provenances of silver fir differing in the altitude of origin (250-1,300 m a.s.l.) were studied using the chlorophyll a fluorescence parameters derived from the JIP-test. Measurements were performed on two dates in 2016: at the start and at the peak of growing season. Within this period, mild water stress was recorded, allowing us to monitor changes in photochemistry under drought conditions. Our results confirmed that silver fir is generally resistant to water deficit at the PSII level. However, the differences in photochemistry between provenances originating from different climatic conditions were observed. The high-altitude provenances (from wetter and colder localities) achieved higher PSII efficiency, which was also supported by clear trends along the climatic and geographic gradients of the provenance origins. After the drought, comparable PSII efficiency for low-altitude provenances and even higher for these originating in higher altitudes was observed.