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

Abstract

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. Abbreviations: DI0/RC − total dissipated energy flux per active reaction centres at t = 0; ea -saturated vapour pressure at a given air temperature; es -free-flowing air vapour pressure; ET0/RC -electron transport flux per reaction centres at t = 0; F0 -basal fluorescence yield of dark-adapted leaf; FM -maximum of fluorescence yield of dark-adapted leaf; FNR -ferredoxin-NADP + -reductase; Ft -fluorescence yield at time t after lightening of actinic light; FV -maximum of variable fluorescence of dark-adapted leaf; M0 -approximated initial slope of the fluorescence transient; PIABS -performance index on absorption basis; PQH2 -plastoquinol, protonated second quinone acceptor; RC/ABS -number of active reaction centres per antenna; TR0/RC -energy trapping by PSII at t = 0; VPD -vapour pressure deficit; Vt -relative variable fluorescence at time t; ∆Vt -the difference in relative variable fluorescence between stressed and control individuals; δRE0 -probability with which a PSII trapped electron is transferred from PSII electron acceptor side to PSI acceptor side; ΦPSII -maximum quantum yield of PSII photochemistry; ΨET0 -probability with which a PSII trapped electron is transferred from PSII beyond reduced QA, ΨET0 = 1 -VJ; ΨRE0 -probability with which a PSII trapped electron is transferred from reduced QA beyond PSI, ΨRE0 = 1 -VI; ΨW -soil water potential.

Toward the Genetic Improvement of Drought Tolerance in Conifers: An Integrated Approach

“…In Abies alba, the chlorophyll a fluorescence was measured, testing five provenances from different altitudes under mild water stress. Significant differences were found, with provenances from higher altitudes showing better performances under both optimal and low-water conditions, suggesting that there were local adaptations to drought and that fluorescence parameters can be applied during plant selection for resistant seedlings [126].…”

Drought or Severe Drought? Hemiparasitic Yellow Mistletoe (Loranthus europaeus) Amplifies Drought Stress in Sessile Oak Trees (Quercus petraea) by Altering Water Status and Physiological Responses

“…The method of chlorophyll a fluorescence can be a sensitive indicator of plant photochemical performance under a wide range of stress factors and it is suitable for assessing photoinhibition [66]. Even though PSII has been considered relatively resistant to drought and is more suitable as an indicator of heat stress than drought [67,68], several studies have used this method and confirmed significant reduction in the photochemical performance under drought conditions [35,68,69]. Moreover, oaks in field conditions may suffer from additive effects, such as heat stress or a hindered ability to regenerate photosystems II [70].…”