Increase In Pigment Content Research Articles

Heavy metal pollution and physiological changes in the leaves of some shrub, palm and tree species in urban areas of Adana, Turkey

The effects of anthropogenic pollution on metal accumulation and some physiological parameters were investigated in plant leaves in the Adana, located in the Mediterranean region of Turkey. Washingtonia filifera L., Eucalyptus camaldulensis L., Phoenix dactylifera L., Platanus orientalis L., Citrus aurantium L., Nerium oleander L. and Schinus molle L. plants were collected from four different locations having different pollution levels in Adana. Concentrations of metals (Al, B, Ba, Fe, Pb, Sr and Zn), pigment (chloropyhll and carotenoid), lipid peroxidation product (malondialdehyde), and peroxidase (POD) enzyme activity were determined in the leaf tissues of these plants. Nerium oleander was determined to be a suitable biomonitor for heavy metal accumulation from anthropogenic and traffic activities in Adana. It was also determined that S. molle accumulated more Cu, Pb and Zn than all the other plant species and that metal accumulation did not cause a significant increase in pigment content of this plant. Our results indicate that POD enzyme activities in P. orientalis (Sr and Zn), C. aurantium (Ba) and N. oleander (Cu and Pb) can be used as suitable indicators for heavy metal stress. Additionally, we propose that S. molle can be used as a biomonitor for Pb, Cu and Zn, while N.oleander can be used as a biomonitor for Fe, Al, and Ba.

Responses of four Indo-West Pacific seagrass species to shading

Seagrasses of the Great Barrier Reef predominantly occur in coastal regions where terrestrial inputs modify water quality and photosynthetic light is highly variable. Responses to shading were tested for Cymodocea serrulata, Halodule uninervis, Thalassia hemprichii and Zostera muelleri. In aquaria, four light treatments – high (66% surface light), moderate (31%), low (14%) and very low light (1%) treatments – were applied for 102d. Stress responses in the low and very low light treatments occurred in the following sequence: metabolic and physiological changes (reduced growth, increased pigment concentrations and photosynthetic efficiency); shedding (leaf loss, shoot loss) and production of new, altered tissue (leaves with reduced length, width and thickness). Complete shoot loss was projected after 76 (Z. muelleri) to 130d (T. hemprichii). Responses were slower in the low than in the very low treatment, therefore, efforts to minimize water quality degradation will be rewarded with delayed impacts to seagrasses.

Stress crack resistance of some pigmented and unpigmented tablet film coating systems.

Stress crack resistance parameters--tensile strength: Young's modulus ratio, relative surface energy, and toughness index--have been examined for unpigmented free films of hydroxypropyl methylcellulose containing polyvinyl alcohol, and polyethylene glycols 400 and 1000, as well as similar film systems pigmented with either talc or titanium dioxide. Incorporation of either polyvinyl alcohol or polyethylene glycols 400 and 1000 in hydroxypropyl methylcellulose film coatings eliminated the incidence of edge splitting in the coated tablets. Increase in pigment concentration generally led to a decrease in the crack resistance of pigmented films. There was a relation between the stress crack resistance of pigmented free films and the incidence of edge splitting of corresponding film coatings applied to aspirin tablets--generally, the higher the crack resistance the lower the incidence of edge splitting. A similar relationship applied to the unpigmented films only when the tensile strength: Young's modulus ratio was considered.

Gloss measurement on film coated tablets.

The gloss of film coated tablets has been assessed using a commercially available specular glossmeter modified to measure the specular reflectance of individual flat-faced, film-coated tablets. For all the pigmented film formulations studied, there was a decrease in gloss with increasing pigment concentration, the magnitude of the decrease being dependent on the pigment used. Film coatings prepared using an aqueous coating system had a much lower gloss reading than those prepared using an organic solvent coating system. Increasing the mean particle size of an inert filler particle resulted in a minimum gloss reading at intermediate particle sizes, while increasing the polymer concentration resulted in a significant decrease in gloss. In the latter case a power law equation was found to fit the data relating the percentage decrease in gloss with the percentage increase in roughness. The results are consistent with the known theories of specular reflectance and illustrate the potential of this rapid and simple technique in the optimization of film formulation and process variables during product development.

Antioxidant Activity of Pigment Extracted from Green-Wheat-Bran

The anthocyanin pigment extracted from green-wheat-bran was studied to identify its antioxidant activity. The antioxidant activities of the pigment were evaluated by anti-lipid peroxidation, total antioxidant activity (TAA), superoxide anion radical scavenging activity (SARSA), active oxygen scavenging activity (AOSA), and DPPH (1,1-diphenyl-2 picrylhydrazyl free radical) radical scavenging activity. The results showed that the pigment had higher antioxidant activity and TAA,. SARSA, AOSA and DPPH scavenging activities at a certain concentration than Vc (antiscorbutic vitamin, vitamin C), and the capacity increased with the increase of pigment concentration. Its TAA was 51.06 U mL −1, 1.73 times of Vc, and SARSA. 18 025.21 U mL −1, 2.26% higher than Vc, and AOSA 3 776.31 U mL −1, 1.24 times of Vc. As to the DPPH scavenging activity of the pigment, there was a trend that higher concentration performed higher activity significantly improved with the company of Vc. The pigment showed significant antioxidant activities evaluated by different assays. Results will provide a better understanding on antioxidant activity of green wheat and allow the screening or breeding of green wheat varieties with higher antioxidant activity for food processing.

Performance properties of pigmented polyvinyl chloride nanocomposites

This work highlighted the role of blue CoO·MgO·Al 2O 3 pigments in changing some properties of PVC composites such as electrical, mechanical and thermal properties. The pigments were prepared by doping different ratios of magnesium in cobalt aluminate crystals using solid–solid interaction. The prepared pigments were characterized by different instrumental analysis (e.g. XRD, SEM and TEM). The influences of different concentrations of nanosized CoO·MgO·Al 2O 3 pigment on PVC prepared by solution blending were studied. The obtained data revealed that PVC nanocomposites containing 1CoO·1MgO·Al 2O 3 pigments show the most promising results. The composites containing 5 wt% of the three compositions of pigments exhibit the optimum electrical, mechanical as well as thermal properties. The relation between tan δ and temperature indicates that T g is not affected by increasing pigment content till 5 wt%, after this concentration, it begins to shift towards higher temperatures. The above investigation led to a conclusion that the optimum recommended concentration of 1CoO·1MgO·Al 2O 3 pigments is 5 wt%. This finding was confirmed by TEM micrographs indicated that inspite that the pigments were prepared in the nano-scale, they tend to agglomerate in the composite reaching the micron-size.

Effects of sediment deposition on periphytic biomass, photosynthetic activity and algal community structure

Suspended solids and siltation are among the most prevalent problems in streams and rivers of the world; however, because they are often associated with other stresses such as increased nutrient concentrations or changes in channel form, their impacts on the biota and on ecosystem functioning are not fully understood. To assess the effects of pulse sediment deposition on periphyton, we applied an exponential gradient of clay concentration (from 0 to 54.7 g L − 1 ) for three days to eleven artificial indoor channels precolonized by algae (three controls + eight treatments). This resulted in a gradient of inorganic particulate matter in the bottom from two to over 200 g m − 2 . Periphytic biomass, photosynthetic activity and algal communities were studied during the following four weeks. High sediment loads (> 6 g L − 1 ) initially reduced algal growth but by the end of the experiment periphytic biomass was similar in all channels. Under high sediment load, algal photosynthetic efficiency showed a quick decrease after three days of exposure, followed by a delayed increase in chlorophyll a contents. After two weeks signs of adaptation were observed, first as an increase in photosynthetic efficiency and then as an increase in pigment concentration. Siltation led to changes in community structure; diatoms increased in high silt treatments although green algae still dominated. Overall, the accumulation of fine sediment affected periphytic biomass, photosynthetic activity and community composition. Periphyton adaptation reduced the initial impact, reaching almost full compensation in terms of chlorophyll a and photosynthetic activity; however, algal community composition did not recover within the time frame of this study. Thus, the frequent siltation pulses observed in many streams throughout the world may have an important impact on the periphyton, which would in turn affect stream ecosystem structure and functioning.

Photosynthetic pigments as indicators of phytoplankton development during spring and summer in Adventfjorden (Spitsbergen)

The study was carried out from April 30 until July 13 of 1997 in Adventfjorden (Spitsbergen). Formation of less saline and warmer surface water (∼1 m thick) caused by melting of the fast ice was observed in the fjord during the first days of May. In summer a less saline surface layer was about 3 m thick. Euphotic depth measured under ice sheet reached 12 m, whereas load of mineral matter brought with riverine discharge in summer (the content of total particulate matter in the fjord reached 1.66 kg m−2) dramatically reduced euphotic zone depth to 0.35 m. By pigment measurement three phases of phytoplankton development in Adventfjorden were distinguished: (1) spring bloom that has started under fast ice and reached maximum in the mid of May, (2) stagnation period in June, (3) increase of pigment concentration in July, what could indicate a start of the next algae bloom. Analyses of chlorophylls and carotenoids revealed that diatoms (chl c, fucoxanthin), and green algae (chl b, lutein) dominated phytoplankton community in the fjord. Moreover, the presence of peridinin indicates the presence of Dinophyta and alloxanthin—the occurence of Cryptophyta. In May and June 1997 phytoplankton appeared mainly in the surface of water, while in July, as a result of inflow of turbulent riverine waters into Adventfjorden, algae cells were pushed down and the highest numbers were observed at the depth ∼20 m. Great phaeopigments to chl a ratio (= 0.54) found in the fjord seston in June and July probably shows strong impact of zooplankton grazing on phytoplankton development. High contribution of chlorophyllide a in porphyrin a poll in samples collected under fast ice (chlorophyllide a/chl a ratio = 0.18) reflects the final stage of algal communitie succession in ice, just before spring ice melt and release of biota to oceanic water. Chloropyllide a content during summer was minor or not detectable, demonstrating that diatom cells were in good physiological condition. High chl a allomer/chl a ratio (average = 0.11 for the period investigated) confirms high oxygen concentration in environment of Adventfjorden.

Sedimentary pigments on the Pakistan margin: Controlling factors and organic matter dynamics

Abstract Sedimentary pigments can provide information on various aspects of benthic processes and biogeochemistry. In this study, sediments from sites at depths of 140 to 1850 m spanning the Pakistan margin oxygen minimum zone (OMZ), and representing dramatic contrasts in depositional conditions and benthic communities, were analysed for pigment yields and compositions. This has allowed a rare consideration of how different factors, including oxygen concentration, organic matter (OM) supply and biological activity (e.g., degree of bioturbation) may influence sedimentary pigment distribution in a continental margin environment. It has also allowed one of the first efforts to study the impact of biological activity on pigment concentrations in the natural environment, rather than in a microcosm setting. Total extractable surface sediment pigment concentrations showed a range of ∼1.5–49 μg g −1 of dry sediment. The pigment suite was dominated by pheophytin and pheophorbide (which together constituted ∼75% of total pigments), with minor amounts of chlorophyll- a , alloxanthin, diatoxanthin, zeaxanthin and β-carotene. Low oxygen concentration appeared to influence pigment abundance by increasing the concentration of refractory pigments ultimately buried. In addition, maximal pigment abundances were associated with minimal amounts of sediment mixing by macrofauna, and at one site macrofaunal digestion may have altered the relative dominance of the different pheopigments. In contrast, the lack of a marked increase in pigment concentrations after the summer monsoon plus the lack of a correlation between pigment concentration and water depth suggest that OM supply plays a relatively small role in controlling sedimentary pigments. Pigment concentrations and suites, together with modelled decay half-lives (∼0.8–15 years), suggest that in general OM on the Pakistan margin, despite the low oxygen concentrations and monsoon-driven productivity, is surprisingly degraded compared to that on other continental margins with OM-rich sediments. As an exception to this general situation, pigment suites appeared to be relatively “fresh” (i.e., contained more labile components) compared to those found on the Oman margin of the Arabian Sea, but overall concentrations were lower. This is consistent with the higher oxygen concentrations, productivity and macrofaunal abundances found on the western margin of the Arabian Sea. Principle component analysis of pigment suites showed that they correlated with an amino-acid-based degradation index (DI). Thus, the pigment composition of marine sediments is related to, and may serve as an indicator of, the state of decay of sedimentary OM.

Antioxidative Defence of Old Growth Beech (Fagus sylvatica) under Double Ambient O3 Concentrations in a Free‐Air Exposure System

In this study the influence of chronic free-air ozone exposure and of different meteorological conditions in the very dry year 2003 and the more humid year 2004 on the antioxidative system in sun and shade leaves of adult FAGUS SYLVATICA trees were investigated. Contents of ascorbate, glutathione, and alpha-tocopherol, as well as chloroplast pigments were determined under ambient (1 x O(3)) and double ambient (2 x O(3)) ozone concentrations. Ozone affected the antioxidative system in June and July, causing lower ascorbate contents in the apoplastic space, a more oxidized redox state of ascorbate and glutathione and an increase in pigment contents predominantly in the shade crown. For all measured parameters significant differences between the years were observed. In 2004 the redox state of ascorbate and glutathione was in a more reduced state and leaf contents of alpha-tocopherol, pigments of the xanthophyll cycle, beta-carotene, lutein, neoxanthin, and alpha-carotene were lower compared to 2003. Contents of total glutathione and chlorophyll a + b were increased in the second year. These results indicate a strong influence of the drought conditions in 2003 on the antioxidative system of beech overruling the ozone effects. Shade leaves showed lower contents of ascorbate in both years and the redox states of ascorbate and glutathione were more oxidized compared to sun leaves. Contents of photoprotective and accessory pigments generally were enhanced and the de-epoxidation state of the xanthophyll cycle was lower in the shade compared to the sun crown. Exhibiting less antioxidants shade leaves seem to be more sensitive against ozone than sun leaves.

Effect of monascus pigment derivatives on the electrophoretic mobility of bacteria, and the cell adsorption and antibacterial activities of pigments

Various amino acid derivatives of monascus pigments were synthesized. The effects of pigment derivatives on the pigment adsorption ratio, electrophoretic mobility (EPM) of bacterial cells, and antibacterial activity were investigated under varying conditions of pigment type, pigment concentration, pH, and ionic strength. Two hydrophobic and two hydrophilic derivatives were selected as model pigments. There was a close relationship between the antimicrobial activity and the pigment adsorption ratio. Against Escherichia coli, the hydrophobic l-Tyr and l-Phe derivatives (log P = 3.18 and 3.57) exhibited high antimicrobial activities (MIC = 8 and 16 mg/L) and high cellular adsorption ratios (9.6 and 10.9 mg/L). The hydrophilic l-Glu and l-Asn derivatives (log P = 1.40 and 0.47) exhibited low activities (MIC = 64 and 128 mg/L) and low adsorption ratios (4.7 and 4.0 mg/L). The electrophoretic mobility of 11 different bacteria varied between −1.93 × 10 −8 and −1.19 × 10 −8 m 2 V −1 s −1 regardless of Gram + or Gram −. The l-Phe derivative showed low MIC values (high antimicrobial activities) against bacteria with a high electrophoretic mobility. A positive linearity between the pigment adsorption ratio and the electrophoretic mobility was established. When the four pigment derivatives were added to E. coli solutions, the electrophoretic mobility of cells in all cases sharply increased with an increasing pigment concentration. The mobility value was high for hydrophobic pigment derivatives in descending order of l-Phe (0.8 × 10 −8 m 2 V −1 s −1), l-Tyr (0.68 × 10 −8 m 2 V −1 s −1), l-Glu (0.46 × 10 −8 m 2 V −1 s −1), and l-Asn (0.44 × 10 −8 m 2 V −1 s −1). Additional adsorption of the hydrophobic derivatives probably occurred due to a hydrophobic interaction between the pigment and the pigment-coated cells. The electrophoretic mobility decreased gradually with an increasing pH and/or ionic strength with both addition and no addition of the pigment derivatives. The pattern of change of the pigment adsorption ratio under varying pH and/or ionic strength values was similar to the pattern for electrophoretic mobility.

Photosynthetic and physiological responses of Kandelia candel L. Druce seedlings to duration of tidal immersion in artificial seawater

The present study demonstrates the influence of the duration of periodical waterlogging with artificial seawater on the photosynthetic and physiological responses of Kandelia candel L. Druce seedlings, the pre-dominant species of subtropical mangroves in China. Artificial tidal fluctuations applied here closely mimicked the twice daily tidal inundation which mangroves experience in the field. All the seedlings were immersed in artificial seawater during 70-day cultivation. Similar trends with increasing duration of immersion occurred in photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO 2 concentration, where significant decreases occurred only in long time treatments of 10 or 12 h. Water used efficiency and chlorophyll contents showed lower in medium periods and higher in long periods of immersion. This indicates that the increase in pigment contents of leaves was ineffective in promoting P n under long time immersion. Light saturation points under short time waterlogging (0–4 h) occurred at light intensities of 800–1000 μmol/m 2/s, and at around 400 μmol/m 2/s in long time treatments (8–12 h). Long periods of tidal immersion therefore significantly inhibited photosynthesis of mature leaves. Alcohol dehydrogenase and oxidase activity in roots both increased under longer immersion periods, suggesting that roots are sensitive to anaerobiosis under long term waterlogging. The activities of peroxidase and superoxide dismutase in mature leaves increased in 8 h and 10 h treatments, respectively. The content of malondialdehyde in mature leaves increased under long time treatments. Abscisic acid accumulation in mature leaves also had a sharp increase from 8 h to 12 h inundation. Even though the anti-oxidative enzymes were induced by waterlogging, this was not sufficient to protect the seedlings from senescence. The results suggested that K. candel seedlings completely tolerated tidal immersion by seawater up to about 8 h in each cycle, which matches the natural distribution of K. candel in inter-tidal zones of China.

Growth and Pigment Content of Container-grown Impatiens and Petunia in Relation to Root Substrate pH and Applied Micronutrient Concentration

The objective was to quantify the effect of substrate pH and micronutrient concentration on growth and pigment content for two floricultural crop species, Petunia ×hybrida `Priscilla' and Impatiens wallerana `Rosebud Purple Magic'. A 70% peat: 30% perlite medium was amended with dolomitic hydrated lime to achieve five substrate pH's ranging from pH 4.4 to 7.0. Plants were grown in 10-cm-diameter pots in a greenhouse for 4 weeks, and irrigated with a fertilizer containing (in mg·L-1) 210N-31P-235K-200Ca-49Mg. Micronutrients were applied using an EDTA (ethylenedinitrilotetraacetic acid) chelated micronutrient blend (C111), at 1×, 2×, and 4× concentrations (in mg·L-1) of 0.50Fe-0.25Mn-0.025Zn-0.04Cu-0.075B-0.01Mo. Petunia shoot dry mass and stem caliper decreased as substrate pH increased, whereas leaf length and width remained unchanged. The highest level of C111 resulted in higher dry mass and smaller leaf area compared with other C111 levels. Overall, substrate pH and C111 had little effect on plant size or mass for impatiens. For both species, increasing substrate pH above 5.3 resulted in a decline in chlorophyll, carotenoids, and the SPAD chlorophyll index (measured with a Minolta-502 SPAD meter) compared with the lowest three pH levels. Chlorosis was observed at pH 7 after 2 weeks of growth. Increasing C111 concentration had no effect on pigment content below pH 5.3, but increased pigment content at higher pH levels. The SPAD index was highly correlated with chlorophyll content. This research emphasizes that an acceptable range in substrate pH can vary depending on fertilizer practices, with higher micronutrient concentration compensating for lower solubility at high substrate pH.

A cytoplasmically inherited mutant controlling early chloroplast development in barley seedlings.

Cytoplasmic line 2 (CL2) has been previously reported as a cytoplasmically inherited chlorophyll-deficient mutant selected from a chloroplast-mutator genotype of barley. It was characterized by a localized effect on the upper part of the first-leaf blade. At emergence the CL2 seedlings-phenotype varied from a grainy light green to an albino color. They gradually greened during the following days, starting from the base of the blade and extending to cover most of its surface when it was fully grown. The present results, from both light microscopy and transmission electron microscopy (TEM), confirmed the previously described positional and time-dependent expression of the CL2 syndrome along the first-leaf blade. During the first days after emergence, light microscopy showed a normally developed chloroplast at the middle part of the CL2 first-leaf blade, meanwhile at the tip only small plastids were observed. TEM showed that the shapes and the internal structure of the small plastids were abnormal, presenting features of proplastids, amyloplasts and/or senescent gerontoplasts. Besides, they lack plastid ribosomes, contrasting with what was observed inside chloroplasts from normal tips, which presented abundant ribosomes. Phenotypic observations and spectrophotometric analysis of seedlings produced by mother plants that had been grown under different temperatures indicated that higher temperatures during seed formation were negatively associated with pigment content in CL2 seedlings. In contrast, higher temperatures during the growth of CL2 seedlings have been associated with increased pigment content. Aqueous solution with kanamycin and streptomycin, which are antibiotics known to interfere with plastid gene translation, were used for imbibition of wild-type and CL2 seeds. Antibiotic treatments differentially reduced the chlorophyll content in the upper part of the first-leaf blade in CL2, but not in wild-type seedlings. These results suggest that in the wild-type, plastid-gene proteins which are necessary for chloroplast development and chlorophyll synthesis in the upper part of the first-leaf blade are usually synthesized during embryogenesis. However, under certain circumstances, in CL2 seedlings, they would be synthesized after germination. In addition, a shortening of the sheath has been observed in association with pigment decrease suggesting the existence of plastid factors affecting the expression of some nuclear genes. We consider the CL2 mutant a unique experimental material useful to study biological phenomena and external factors regulating plastid, and nuclear gene expression during embryogenesis and early seedling development.

Vertical heterogeneity in physiological characteristics of Ulva spp. mats

In eutrophic areas, green macroalgae are frequently and for long periods arranged in mats, resulting in a steep light gradient. This study investigates the effect of this gradient on physiological characteristics [tissue nitrogen content, maximal photosynthetic efficiency (Fv/Fm), glutathione levels and redox ratio, absorbance and absorption spectra] of the green macroalga Ulva spp. Mats were sampled during the build-up (June), stationary (July), and decomposing (September) phases of a macroalgal bloom in the Veerse Meer, a eutrophic brackish (salinity 15–20 psu) lake in the southwest Netherlands. Water samples were taken for nutrient analyses. At all three sampling dates, the mats were composed almost entirely of Ulva spp.; in September the mats were in decay and covered with silt and epiphytes. In June and July, total dissolved inorganic nitrogen concentration (DIN) of the water within the mat was significantly higher than outside the mat. Pronounced vertical differences were found in tissue N, Fv/Fm values, total glutathione levels, glutathione redox ratios, and absorbance. In June and July, tissue N decreased from over 2.2% dry weight (DW; N-sufficient) in the bottom layers to around 1% DW (minimum level for survival) in the top layers. Wide-band absorption increased with depth in the mat and throughout the season, probably due to higher Chl a and b and lutein contents. The shape of the absorption spectrum was similar for all layers. The absorption of the silt/epiphyte film on the top Ulva layer was highest; its absorption spectrum (high absorption in the 500–560 nm range) indicates that the film on the top layers of the macroalgal mats mainly consisted of diatoms. In June, Fv/Fm and the glutathione redox ratio of the algae increased with depth in the layer, while total glutathione decreased. Low Fv/Fm values in the bottom and middle layers in September reflect the bad condition of the algae; the mats were largely decaying. It is concluded that multiple growth-limiting gradients occur in macroalgal mats: upper layers suffer from nitrogen limitation and photoinhibition while bottom layers are light limited. The algae in the mat acclimatize to low light conditions by increasing their absorption through increased pigment contents and by higher photosynthetic efficiency during the build-up and stationary period. This study qualifies the glutathione redox ratio as a promising candidate for stress indicator in macroalgae and provides suggestions for its further development.

Effects of fludioxonil and pyrimethanil, two fungicides used against Botrytis cinerea, on carbohydrate physiology in Vitis vinifera L.

In Vitis vinifera L, photosynthesis and photosynthate partitioning are affected in the presence of fludioxonil and pyrimethanil, two fungicides commonly used in vineyards against Botrytis cinerea Pers. However, the effects were found to be different according to the model studied: plantlets (cv Chardonnay) grown in vitro, fruiting cuttings (cv Chardonnay) and plants grown in vineyards (cvs Chardonnay, Pinot noir and Pinot Meunier). In the plantlets grown in vitro, both fungicides decreased gas exchanges, photosynthetic pigment and starch concentrations in the leaves, whereas soluble carbohydrates transiently accumulated, suggesting that plantlets mobilised starch in response to photosynthesis inhibition caused by fungicides. In the fruiting cuttings, the fungicides did not affect photosynthesis, although fludioxonil caused starch decrease in parallel with sucrose accumulation, suggesting that the fungicide effects were of lower intensity than in vitro. Conversely, in vineyard, the two fungicides stimulated photosynthesis and increased pigment concentrations in the three vine cultivars tested. In the meantime, glucose, fructose and starch levels of the leaves declined after fungicide exposure, whereas sucrose accumulated, indicating that sucrose synthesis increased in the leaves following the fungicide treatment. Among the three varieties, Chardonnay was the most sensitive to the fungicides as revealed by the intensity of the responses and the longer period for recovery. In vineyard, the results suggested that the two fungicides, in addition to inhibiting B cinerea development, had a beneficial effect on vine physiology through the stimulation of leaf carbon nutrition, which may further enable the plant to rapidly make use of its defence reactions.

Plant Pigments in the Ivankovo Reservoir Silts as Indicators of Destruction Processes

The trophic state of the Ivankovo Reservoir is evaluated based on the characteristics of phytoplankton development and silt accumulation. Data on the space and time distribution of plant pigments in silt deposits are examined. Correlation between plant pigments and the main characteristics of silts are established. The ratio of chlorophyll content of the normal annual layer of sediment accumulation to the annual primary production of phytoplankton is calculated. The bedding of gray clayey silts onto gray sandy silts is shown to correlate with an increase in pigment concentrations in the top sediment horizons.

Variation in Light Absorption Properties of Mentha aquatica L. as a Function of Leaf Form: Implications for Plant Growth

To understand the association between leaf form and leaf optical properties, we examined light absorption variations in the leaves of Mentha aquatica L., an amphibious freshwater macrophyte. Specific absorption of leaves of M. aquatica showed a 7.5‐fold variation, decreasing as pigment per unit area increased. This relationship indicates that dispersive samples, such as leaves, although efficient light traps, can also be affected by the “package effect.” Mentha aquatica leaves, by expanding their biomass (increased specific leaf area [SLA]), improve their light absorption efficiency per unit of both pigment and leaf biomass. Changes in leaf biomass expansion were mainly a result of changes in leaf density, and as a consequence, leaf density appears to be a better descriptor of light absorption efficiency in M. aquatica leaves than does leaf thickness. Light absorption efficiency per unit of leaf biomass was also enhanced by increasing pigment content. Our results indicate that M. aquatica produces two typ...

Response of a shallow boreal lake to recent nutrient enrichment – implications for diatom-based phosphorus reconstructions

Water quality of the shallow, mesotrophic, and macrophyte-dominated Lake Kaljasjarvi has been monitored at three to four year intervals since 1978. During the monitoring period, surface-water total phosphorus (TP) concentrations have typically varied between 20 and 25 μg P l−1. However, elevated total phosphorus concentrations were measured in 1987, 1991, and 1999. Diatom-based reconstruction of the historical lake-water TP concentrations was therefore employed to study the recent development of the lake. However, the diatom-TP model did not predict the high measured phosphorus concentrations despite the changes observable in diatom assemblages. In addition, the ratio of sedimentary diatom remains to chrysophycean stomatocysts declined towards the top of the sediment core, indicating decreasing trophy rather than eutrophication. Analysis of sedimentary pigments and phosphorus fractions, used to examine further the changes, also produced results that contradicted the simple eutrophication hypothesis. In particular, the proportion of chlorophyll derivatives instead of carotenoids increased and there was a rise in the concentration of refractory instead of NaOH-extracted phosphorus. These features appear to be related to the extensive littoral areas of the lake since enhanced littoral production can explain both the observed changes in sediment chemistry and the low diatom-inferred TP (DI-TP). Littoral primary producers are suggested to have benefited from the increased phosphorus inputs to the lake, transferring some of the phosphorus to the detrital pool and contributing to the increased pigment concentrations of sedimentary organic matter. High proportions of non-planktonic diatoms in the samples lower DI-TP because periphytic taxa are assigned low TP optima in the inference models used. Abundant aquatic macrophytes may also have made the lake resistant to eutrophication by assimilating nutrients, providing refuge for zooplankton, and having an allelopathic effect on phytoplankton. Since ∼1980, however, the sedimentary diatom assemblages also indicate increasingly eutrophic conditions. Additional loading from numerous cottages during the last 20 years seems to have caused observable changes in the phytoplankton communities.

Pigments as biomarkers of exposure to the vineyard herbicide flazasulfuron in freshwater algae

Weed control in Champagne vineyards has long relied on the use of diuron and substituted triazines; these compounds are now being replaced by flazasulfuron, a sulfonylurea that is used at a much lower dosage. The vineyards of Champagne are planted on steep slopes and runoff is important, and even though low doses of these herbicides are used, they may present some potential risk for freshwater ecosystems. Therefore, the effects of the sulfonylurea herbicide, flazasulfuron (formulated as Katana) was investigated on the unicellular green alga Scenedesmus obliquus. The pigment content of the algal suspensions was followed as a biomarker of exposure to the herbicide. The results demonstrate that flazasulfuron induced a reduction in chlorophyll content at concentrations of 10 μg/L, while the increase of pigment content in the culture was reduced with the lowest concentration tested (0.1 μg/L). Among the three pigments tested, chlorophyll a appeared to be the most sensitive biomarker. In the algal medium, flazasulfuron was slowly degraded (DT 50 approximately 8 days) in a compound that was tentatively identified. The toxicity of this herbicide for the algae was comparable to that of older herbicides which are used at a much higher rate. Therefore, we may speculate that even if flazasulfuron comes into contact with freshwater ecosystems, its effects on algae will be less deleterious than that of traditional herbicides.