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  • 1
    Electronic Resource
    Electronic Resource
    Effects of combined NaCl and CaCl2 salinity on photosynthetic parameters of barley grown in nutrient solution (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The changes caused by NaCl− and CaCl2-induced salinity on several leaf parameters have been measured in two cultivars of barley (Hordeum vulgare L.) growing in a growth chamber in nutrient solution. Salinity was induced by adding to the nutrient solution equal weights of NaCl and CaCl2, to obtain conductivities of 2, 6, 12, 19 and 26 dS m−1. Salinity induced decreases in the leaf water potential and in the osmotic potential. Salinity did not induce significant changes in the relative photosynthetic pigment composition of barley leaves, the photosynthetic pigment stoichiometry for neoxanthin:violaxanthin cycle pigments:lutein:β-carotene:Chl b:Chl a being close to 3:6:14:12:25:100 (mol:mol). Salinity per se did not induce interconversions in the carotenoids within the violaxanthin cycle in most barley leaves. The PSII photochemistry of most barley leaves was unchanged by salinity. However, some apparently healthy leaves growing in high salinity exhibited sudden decreases in PSII photochemistry and increases in zeaxanthin (at the expense of violaxanthin), that preceded rapid leaf drying. Salinity induced significant changes in the slow part of the chlorophyll fluorescence induction curve from barley leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb01338.x
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  • 2
    Electronic Resource
    Electronic Resource
    Changes induced by Fe deficiency and Fe resupply in the organic acid metabolism of sugar beet (Beta vulgaris) leaves (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of iron deficiency and iron resupply on the metabolism of leaf organic acids have been investigated in hydroponically grown sugar beet. Organic acid concentrations and activities in leaf extracts of several enzymes related to organic acid metabolism were measured. Enzymes assayed included phosphoenol pyruvate carboxylase (PEPC; EC 4.1.1.31), different Krebs cycle enzymes: malate dehydrogenase (MDH; EC 1.1.1.37), aconitase (EC 4.2.1.3), fumarase (EC 4.2.1.2), citrate synthase (CS; EC 4.1.3.7) and isocitrate dehydrogenase (ICDH; EC 1.1.1.42), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and two enzymes related to anaerobic metabolism (lactate dehydrogenase [LDH]; EC 1.1.1.27, and pyruvate decarboxylase [PDC]; EC 4.1.1.1). Iron concentration in leaves was severely decreased by iron deficiency. Iron resupply caused an increase in iron concentrations, reaching levels similar to the controls in 96 h. Iron deficiency induced a 2.3-fold (from 16 to 37 mmol m−2) increase in leaf total organic acid concentration. Organic anion concentrations were still 4-fold higher than the controls 24 h after resupply and decreased to values similar to those found in the controls after 96 h. All measured enzymes had increased activities in extracts of iron-deficient leaves when compared to the controls and generally decreased to control values 24 h after iron addition. These data provide evidence that organic acid accumulation in iron-deficient leaves is likely not due to an enhancement in leaf carbon fixation. Instead, this accumulation could be associated with organic acid export from the roots to the leaves via xylem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120105.x
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  • 3
    Electronic Resource
    Electronic Resource
    Changes in net photosynthesis, chlorophyll fluorescence and xanthophyll cycle interconversions during freeze-thaw cycles in the Mediterranean moss Leucodon sciuroides (1999)
    Springer
    Oecologia 120 (1999), S. 499-505 
    Details
    ISSN: 1432-1939
    Keywords: Key words Bryophytes ; Chlorophyll a fluorescence ; Downregulation ; Freezing tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The tolerance to freezing and thawing of Leucodon sciuroides, a moss growing in mountainous areas of the Mediterranean (south-east Spain), was investigated by means of CO2 gas exchange, modulated chlorophyll (Chl) a fluorescence and pigment analysis by high-performance liquid chromatography. Evidence is presented for freezing-induced decreases in CO2 fixation that enhance non-radiative dissipation of absorbed light energy, a process which protects the photosynthetic apparatus. The photosynthetic apparatus of L. sciuroides remained fully recuperable after freezing, as indicated by the recovery of photosynthetic CO2 fixation and Chl fluorescence parameters to pre-freezing values during thawing. The rapid recovery of photosynthesis activity during thawing in L. sciuroides suggests that this moss is capable of tolerating freeze-thaw cycles in a manner similar to that found at higher latitudes or in the Antarctic. The resistance of the photosynthetic apparatus of this moss to freezing might be achieved, at least partially, through the employment of dissipative pathways, such as non-radiative dissipation of absorbed light energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050883
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  • 4
    Electronic Resource
    Electronic Resource
    Photosystem II efficiency in low chlorophyll, iron-deficient leaves (1999)
    Springer
    Plant and soil 215 (1999), S. 183-192 
    Details
    ISSN: 1573-5036
    Keywords: energy dissipation ; iron deficiency ; chlorosis ; Photosystem II efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Iron deficiency (iron chlorosis) is the major nutritional stress affecting fruit tree crops in calcareous soils in the Mediterranean area. This work reviews the changes in PS II efficiency in iron-deficient leaves. The iron deficiency-induced leaf yellowing is due to decreases in the leaf concentrations of photosynthetic pigments, chlorophylls and carotenoids. However, carotenoids, and more specifically lutein and the xanthophylls of the V+A+Z (Violaxanthin+ Antheraxanthin+Zeaxanthin) cycle are less affected than chlorophylls. Therefore, iron-chlorotic leaves grown in either growth chambers or field conditions have increases in the molar ratios lutein/chlorophyll a and (V+A+Z)/chlorophyll a. These pigment changes are associated to changes in leaf absorptance and reflectance. In the chlorotic leaves the amount of light absorbed per unit chlorophyll increases. The low chlorophyll, iron-deficient leaves showed no sustained decreases in PS II efficiency, measured after dark adaptation, except when the deficiency was very severe. This occurred when plants were grown in growth chambers or in field conditions. However, iron-deficient leaves showed decreases in the actual PS II efficiency at steady-state photosynthesis, due to decreases in photochemical quenching and intrinsic PS II efficiency. Iron-chlorotic leaves were protected not only by the decrease in leaf absorptance, but also by down-regulation mechanisms enhancing non-photochemical quenching and thermal dissipation of the light absorbed by PS II within the antenna pigment bed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004451728237
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  • 5
    Electronic Resource
    Electronic Resource
    Iron deficiency in peach trees: effects on leaf chlorophyll and nutrient concentrations in flowers and leaves (1998)
    Springer
    Plant and soil 203 (1998), S. 257-268 
    Details
    ISSN: 1573-5036
    Keywords: iron chlorosis ; nutrient composition ; peach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of iron deficiency on the leaf chlorophyll concentrations and on the macro- (N, P, K, Ca and Mg) and micro-nutrient (Fe, Mn, Zn and Cu) composition of flowers (at full bloom) and leaves (60 and 120 days after full bloom) of field-grown peach (Prunus persica L. Batsch) trees were investigated. Flowers and leaves were taken and analysed from fifty individual trees. Our data indicate that large decreases in leaf chlorophyll concentration were found at the beginning of the season in control trees, possibly associated to a ‘dilution’ effect by leaf growth, that were later followed by leaf chlorophyll concentration increases. Leaf Fe chlorosis apparently results from two different processes, the dilution of leaf Chl caused by growth and the subsequent inability to produce and/or stabilize new Chl molecules in the thylakoid membrane. Iron chlorosis did not change the seasonal change patterns of any of the nutrients studied. In Fe-deficient trees the K concentration and the K/Ca ratio were high not only in leaves but also in flowers, indicating that this is a characteristic of Fe-deficient plant tissue in the whole fruit tree growing season. Flower Fe concentrations were well correlated with the degree of chlorosis developed later in the season by the trees, suggesting that flower analysis could be used for the prognosis of Fe deficiency in peach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004373202458
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  • 6
    Electronic Resource
    Electronic Resource
    Spectral characterization of NAD(P)H fluorescence in intact isolated chloroplasts and leaves: Effect of chlorophyll concentration on reabsorption of blue-green fluorescence (1998)
    Springer
    Photosynthesis research 56 (1998), S. 291-301 
    Details
    ISSN: 1573-5079
    Keywords: blue-green fluorescence (BGF) ; intact isolated chloroplasts ; Pisum sativum ; photosynthesis ; pyridine nucleotides ; Spinacia oleracea L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present communication we report a spectral analysis of the blue-green fluorescence related to changes in NAD(P) redox state in chloroplasts and leaves. To assess the contribution of reabsorption and the inner filter effect, we compared transmission and fluorescence at different chloroplast concentrations, and showed that reabsorption by the photosynthetic pigments (chlorophylls and carotenoids) was at the origin of the two peaks in the emission spectrum in vivo. The absence of potential green-emitting fluorophores in chloroplasts was determined by measuring variable and time-resolved fluorescence at different wavelengths. We defined the conditions which optimize the UV-excited blue-green fluorescence signal dependent on NAD(P)H, and we present an example of monitoring of NAD(P)H fluorescence in intact leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006081209887
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  • 7
    Electronic Resource
    Electronic Resource
    Photosystem II efficiency and mechanisms of energy dissipation in iron-deficient, field-grown pear trees (Pyrus communis L.) (2000)
    Springer
    Photosynthesis research 63 (2000), S. 9-21 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; energy dissipation ; field-grown pear ; iron deficiency ; Photosystem II efficiency ; Pyrus communis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dark-adapted Photosystem II efficiency of field-grown pear leaves, estimated by the variable to maximum chlorophyll fluorescence ratio, was little affected by moderate and severe iron deficiency. Only extremely iron-deficient leaves showed a decreased Photosystem II efficiency after dark adaptation. Midday depressions in Photosystem II efficiency were still found after short-term dark-adaptation in iron-deficient leaves, indicating that Photosystem II down-regulation occurred when the leaves were illuminated by excessive irradiance. The actual Photosystem II efficiency at steady-state photosynthesis was decreased by iron deficiency both early in the morning and at midday, due to closure of Photosystem II reaction centers and decreases of the intrinsic Photosystem II efficiency. Iron deficiency decreased the amount of light in excess of that which can be used in photosynthesis not only by decreasing absorptance, but also by increasing the relative amount of light dissipated thermally by the Photosystem II antenna. When compared to the controls, iron-deficient pear leaves dissipated thermally up to 20% more of the light absorbed by the Photosystem II, both early in the morning and at midday. At low light iron-deficient leaves with high violaxanthin cycle pigments to chlorophyll ratios had increases in pigment de-epoxidation, non-photochemical quenching and thermal dissipation. Our data suggest that ΔpH could be the major factor controlling thermal energy dissipation, and that large (more than 10-fold) changes in the zeaxanthin plus antheraxanthin to chlorophyll molar ratio caused by iron deficiency were associated only to moderate increases in the extent of photoprotection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006389915424
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  • 8
    Electronic Resource
    Electronic Resource
    Iron deficiency causes changes in chlorophyll fluorescence due to the reduction in the dark of the Photosystem II acceptor side (1998)
    Springer
    Photosynthesis research 56 (1998), S. 265-276 
    Details
    ISSN: 1573-5079
    Keywords: Beta vulgaris ; iron chlorosis ; iron deficiency ; plant nutrition ; plastoquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Iron deficiency was found to affect the redox state of the Photosystem II acceptor side in dark-adapted, attached leaves of sugar beet (Beta vulgaris L.). Dark-adapted iron-deficient leaves exhibited relatively high Fo and Fpl levels in the Kautsky chlorophyll fluorescence induction curve when compared to the iron-sufficient controls. However, far-red illumination led to marked decreases in the apparent Fo and Fpl levels. Modulated fluorescence showed that far-red light decreased the fluorescence yield to the true Fo levels by increasing photochemical quenching, without inducing changes in the level of non-photochemical quenching. In dark-adapted, iron-deficient leaves, far-red illumination induced a faster fluorescence decay in the µs-ms time domain, indicating an improvement in the electron transport after the primary quinone acceptor in the reducing side of Photosystem II. All these data indicate that in iron-deficient leaves the plastoquinone pool was reduced in the dark. The extent of the plastoquinone reduction in sugar beet depended on the chlorophyll concentration of the leaf, on the time of preillumination and on the duration of dark adaptation. The dark reduction of plastoquinone was observed not only in sugar beet but also in other plant species affected by iron deficiency both in controlled conditions and in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006039917599
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  • 9
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    Time-Resolved Spectral Studies of Blue−Green Fluorescence of Artichoke (Cynara cardunculusL. Var.Scolymus) Leaves:  Identification of Chlorogenic Acid as One of the Major Fluorophores and Age-Mediated Changes (2005)
    American Chemical Society
    Details
    Publication Date: 2005-12-01
    Print ISSN: 0021-8561
    Electronic ISSN: 1520-5118
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Published by American Chemical Society
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  • 10
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    Growth, Yield, and Fruit Quality of Pepper Plants Amended with Two Sanitized Sewage Sludges (2010)
    American Chemical Society
    Details
    Publication Date: 2010-06-09
    Print ISSN: 0021-8561
    Electronic ISSN: 1520-5118
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Published by American Chemical Society
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