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.
The influence of pollution stress (SO2, Cu 2+, Pb 2+, Zn 2+ and fluoride) on composition changes in cellular membranes of roots of three European of Scots pine (Pinus sylvestris L.) populations were examined. Plant material growing in three experimental areas: K6rnik relatively free of air pollution (control), Lubofi: SO2 and HF and Gtog6w: SO2 and heavy metals. Analysis of total phospholipids and their composition indicates that the phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were present in lower concentration in the root tissues from both polluted sites (Lubofi and Gtog6w). The difference in PC:PE ratio between control and both polluted sites was greater in root of Scots pine population from Russia than in the population from Slovakia. Under pollution conditions the content of lipid soluble antioxidant c~-tocopherol was lower about 220 %, in comparison to the control. The action of pollution stress also lead to lowering of unsaturated: saturated ratio of total fatty acid, and lower content of polyunsaturated fatty acids, linoleic acid (18:2) and eicosatrienoic acid (20:3). We concluded that the long-term pollution stress markedly inhibited lipid biosynthesis in root tissue of Scots pine and it is probably contribute to the reduction of productivity of forests. These resuits also suggest that lipid composition can be used as an indicator of changes in tissue roots of Scots pine caused by air and/or soil long-term pollution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.