Effect of drought stress on chlorophyll a fluorescence and electrical admittance of shoots in Norway spruce seedlings

Abstract

Effects of mild and severe soil drought on the water status of needles, chlorophyll a fluorescence, shoot electrical admittance, and concentrations of photosynthetic pigments in needles of seedlings of Picea abies (L.) Karst. were examined under controlled greenhouse conditions. Drought stress reduced shoot admittance linearly with a decrease in shoot water potential ( w ) and increase in water deficit (WD) and led to a decrease in concentrations of chlorophyll a, b and carotenoids. Severe water stress (shoot w =−2.4 MPa) had a negative effect on chlorophyll a fluorescence parameters including PSII activity (F v /F m ), and the vitality index (R fd ). Variations in these parameters suggest an inhibition of the photosynthetic electron transport in spruce needles. Water stress led to a decrease in the mobility of electrolytes in tissues, which was reflected by decreased shoot electrical admittance. After re-watering for 21 days the WD in needles decreased and the shoot water potential increased. In the re-watered plants, the chloroplast function was restored and chlorophyll a fluorescence returned to a similar level as in the control plants. This improved hydraulic adjustment in the seedlings triggered a positive effect on ion flow in the tissues and increased shoot electrical admittance. We conclude that the shoot electrical admittance and photosynthetic electron transport in leaves are closely linked to changes in water status and their decrease is among the initial responses of seedlings to water stress.

Monoterpene responses to interacting effects of drought stress and infection by the fungus Heterobasidion parviporum in two clones of Norway spruce (Picea abies)

“…Changes in chlorophyll fluorescence in young interior spruce trees during drought stress were found to reflect down-regulation of primary photochemistry and the augmentation of photoprotective mechanisms to avoid over-reduction and photoinhibitory damage (Eastman and Camm, 1995). A similar drop in the potential photochemical efficiency of PSII with drought stress was previously observed in Norway spruce (Pukacki and Kaminska-Rozek, 2005;Ditmarová et al, 2010); although, in contrast to our experiment, values did not recover to pre-stress conditions. Bigras (2005) observed an initial drop in the potential photochemical efficiency of PSII at leaf water potential ranging from −1 to −2 MPa.…”

Leaf rolling and photosystem II efficiency in Ctenanthe setosa exposed to drought stress

“…Rfd is a good indicator of whole plant physiological state (Pukacki and Kamińska-Rożek 2005). Rfd values above 3.0 indicate very efficient photosynthesis and high photosynthetic rates per leaf area unit while at Rfd values below 1.0, the leaves no longer exhibit a net CO 2 assimilation (reviewed by Lichtenthaler and Rinderle 1988).…”

Morphological, anatomical and physiological responses of Campylotropis polyantha (Franch.) Schindl. seedlings to progressive water stress

“…The initial fluorescence (F 0 ), maximal fluorescence (F m ) and maximal PS II photochemical efficiency (F v /F m ) were measured in dark-adapted leaves that had been enclosed in a leaf-clip holder (2030B, Heinz Walz) for 30 min. The effective quantum yield of PS II (˚P SII ), photochemical (qP) and non-photochemical (NPQ) fluorescence quenching coefficients were measured in light-adapted leaves under light conditions, with the pulse being delivered at 600 mmol m −2 s −1 for 0.8 s. The experimental protocol was as described previously (Pukacki and Kamińska-Rożek, 2005;Wu et al, 2008b). …”

“…Next, the samples were dried in an oven for 48 h at 70 • C and the dry weight (DW) was determined. The RWC was calculated using the following formula: RWC (%) = [(FW − DW)/(TW − DW)] × 100 (Pukacki and Kamińska-Rożek, 2005).…”

“…Decline in RWC under drought condition leads to stomatal closure (Chartzoulakis et al, 1999;Gindaba et al, 2004), further resulting in decreased CO 2 assimilation. As drought deepens, plant can change the physiological state of the photosynthesis apparatus which can be reflected by lower chlorophyll a fluorescence (i.e., F v /F m and˚P SII ) and increased dissipation of excess excitation energy (i.e., NPQ) of the leaves (Pukacki and Kamińska-Rożek, 2005;Gallé et al, 2007). The pigment contents generally also decrease due to their low synthesis rate and rapid degradation with water stress (Mihailovié et al, 1997;Lei et al, 2006).…”