Potential for phytoextraction of copper by Sinapis alba and Festuca rubra cv. Merlin grown hydroponically and in vineyard soils

The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical-physical properties. After the amendment of Cu (5 or 10 mg Cu l-(1)) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg(-1) DW, more than three times higher than in S. alba (31.56 mg Cu kg(-1) DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to threefold to fourfold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.

Phytotoxkit/Phytotestkit and Microtox® as tools for toxicity assessment of sediments

The aim of the study was to use bioassays to evaluate the toxicity of pore water, sediments and sediments elutriates. Furthermore, a possible relationship between observed toxicity and results of chemical analysis was examined. Sediment (0-10 cm) samples were collected from 21 locations in Zeslawice reservoir, Southern Poland using an Ekman sampler. Toxicity assessment of the sediment and pore water samples was performed using direct-contact tests Phytotoxkit/Phytotestkit and Microtox®. Inhibition of seed germination in the test plants was from -25 to 38 percent for sediment and from 0 to 50 percent for pore water, whereas inhibition of root growth was within a range from -42 to 37 percent for sediment and from -49 to 37 percent for pore water. Depending on the sediments, Vibrio fischeri luminescence inhibition was from -18 to 40 percent for sediments elutriates and from -12 to 28 percent for pore water. The toxicity tests showed a positive correlation between metals and the root growth inhibition in Lepidium sativum and Sinapis alba as well as the luminescence inhibition in V. fischeri. No significant correlations were found between the inhibition of luminescence and the phytotoxicity assays, so these analyses do not show a similar sensitivity to toxicants in the sediments. While estimating the sensitivity of the performed biotests, the highest number of toxic responses was recorded in the Microtox® test towards V. fischeri. Among the plant species, Sorghum saccharatum appears to be the most sensitive plant species. Most of the examined sediment samples (67 percent) were classified as class II (low-toxic samples, low acute hazard) and 33 percent of the examined samples were class I (no essential toxic effect, non-toxic sample, no acute hazard) in terms of toxicity. Most of the pore water samples (71 percent) were also classified as class II.

Functional analysis of the promoter of a glycosyl hydrolase gene induced in resistant Sinapis alba by Alternaria brassicicola

A putative family 3 glycosyl hydrolase (GH) gene showed significant differential expression in resistant Sinapis alba, compared with the susceptible Brassica juncea, as part of the initial responses during interaction with the necrotroph Alternaria brassicicola. To understand the mechanism of induction, the promoter was isolated and deletion analysis carried out. All the promoter fragments were fused with the β-glucuronidase gene and the expressions were studied in stable B. juncea transgenics and transiently transformed Nicotiana tabacum. Analysis of the expression of the promoter showed the presence of functional abscisic acid (ABA)-, jasmonic acid (JA)-, and salicylic acid (SA)-responsive cis elements. Interestingly, the promoter was found to be induced in both S. alba and B. juncea upon challenge with A. brassicicola but, in S. alba, SA had an inhibitory effect on the pathogen-induced expression of the gene whereas, in B. juncea, SA did not have any negative effect. Therefore, the SA-mediated inhibition in S. alba indicates that the induction is probably through JA or ABA signaling. The difference in the mechanism of induction of the same promoter in the resistant and susceptible plants is probably due to the differential hormonal responses initiated upon challenge with A. brassicicola.

Assessment of the phytotoxicity of seaport sediments in the framework of a quarry-deposit scenario: germination tests of sediments aged artificially by column leaching

The aim of the Sustainable Management of Sediments Dredged in Seaports (SEDIGEST) project is to assess the risks of treated port sediments for terrestrial ecosystems when deposited in quarries. We simulated the "ageing" of these sediments up to the "moment" when plants can germinate. Sediments were leached by water percolating through a laboratory column. Sediments 1 and 2, taken from the port of Toulon (France), were dried and aired. Sediment 3, taken from the port of Guilvinec (France), was stabilised with lime. Phytotoxicity was evaluated on the three artificially aged sediments using germination and early development tests (48 h to 7 days) by Phytotoxkit F(TM) bioassays. The three dilutions tested were performed with the reference "ISO substrate" and with Lolium perenne sp. (rye grass), Sinapis alba (white mustard), and Lepidium sativum (watercress). The tests performed with sediments 1 and 2 showed (1) a decrease of their toxicity to the germination of the species selected following leaching and (2) that L. perenne was the most sensitive species. The tests performed with sediment 3 showed that it was improper for colonisation even after leaching simulating 16 months of ageing. These germination tests on aged sediments identified the effects of leaching and made it possible to appreciate the capacity of the sediments to allow colonisation by plants.

Phase-dependent phytoavailability of thallium--a synthetic soil experiment

The study deals with the environmental stability of Tl-modified phases (ferrihydrite, goethite, birnessite, calcite and illite) and phytoavailability of Tl in synthetically prepared soils used in a model vegetation experiment. The data presented here clearly demonstrate a strong relationship between the mineralogical position of Tl in the model soil and its uptake by the plant (Sinapis alba L.). The maximum rate of Tl uptake was observed for plants grown on soil containing Tl-modified illite. In contrast, soil enriched in Ksat-birnessite had the lowest potential for Tl release and phytoaccumulation. Root-induced dissolution of synthetic calcite and ferrihydrite in the rhizosphere followed by Tl mobilization was detected. Highly crystalline goethite was more stable in the rhizosphere, compared to ferrihydrite, leading to reduced biological uptake of Tl. Based on the results obtained, the mineralogical aspect must be taken into account prior to general environmental recommendations in areas affected by Tl.

Histological, cytological and biochemical alterations induced by microcystin-LR and cylindrospermopsin in white mustard (Sinapis alba L.) seedlings

This study compares the histological, cytological and biochemical effects of the cyanobacterial toxins microcystin-LR (MCY-LR) and cylindrospermopsin (CYN) in white mustard (Sinapis alba L.) seedlings, with special regard to the developing root system. Cyanotoxins induced different alterations, indicating their different specific biochemical activities. MCY-LR stimulated mitosis of root tip meristematic cells at lower concentrations (1 μg ml-1) and inhibited it at higher concentrations, while CYN had only inhibitory effects. Low CYN concentrations (0.01 μg ml-1) stimulated lateral root formation, whereas low MCY-LR concentrations increased only the number of lateral root primordia. Both inhibited lateral root development at higher concentrations. They induced lignifications, abnormal cell swelling and inhibited xylem differentiation in roots and shoots. MCY-LR and CYN induced the disruption of metaphase and anaphase spindles, causing altered cell divisions. Similar alterations could be related to decreased protein phosphatase (PP1 and PP2A) activities in shoots and roots. However, in vitro phosphatase assay with purified PP1 catalytic subunit proved that CYN in contrast to MCY-LR, decreased phosphatase activities of mustard in a non-specific way. This study intends to contribute to the understanding of the mechanisms of toxic effects of a protein phosphatase (MCY-LR) and a protein synthesis (CYN) inhibitory cyanotoxin in vascular plants.

Solar photo-Fenton process on the abatement of antibiotics at a pilot scale: Degradation kinetics, ecotoxicity and phytotoxicity assessment and removal of antibiotic resistant enterococci

This work investigated the application of a solar driven advanced oxidation process (solar photo-Fenton), for the degradation of antibiotics at low concentration level (μg L(-1)) in secondary treated domestic effluents at a pilot-scale. The examined antibiotics were ofloxacin (OFX) and trimethoprim (TMP). A compound parabolic collector (CPC) pilot plant was used for the photocatalytic experiments. The process was mainly evaluated by a fast and reliable analytical method based on a UPLC-MS/MS system. Solar photo-Fenton process using low iron and hydrogen peroxide doses ([Fe(2+)](0) = 5 mg L(-1); [H(2)O(2)](0) = 75 mg L(-1)) was proved to be an efficient method for the elimination of these compounds with relatively high degradation rates. The photocatalytic degradation of OFX and TMP with the solar photo-Fenton process followed apparent first-order kinetics. A modification of the first-order kinetic expression was proposed and has been successfully used to explain the degradation kinetics of the compounds during the solar photo-Fenton treatment. The results demonstrated the capacity of the applied advanced process to reduce the initial wastewater toxicity against the examined plant species (Sorghum saccharatum, Lepidium sativum, Sinapis alba) and the water flea Daphnia magna. The phytotoxicity of the treated samples, expressed as root growth inhibition, was higher compared to that observed on the inhibition of seed germination. Enterococci, including those resistant to OFX and TMP, were completely eliminated at the end of the treatment. The total cost of the full scale unit for the treatment of 150 m(3) day(-1) of secondary wastewater effluent was found to be 0.85 € m(-3).

Plants as models for chromium and nickel risk assessment

The adverse effects of Cr(III), Cr(VI), and Ni(II) expressed as root and shoot growth inhibition, metal accumulation and translocation throughout plants, and genotoxicity study were examined. To examine phytoxicity and metal accumulation, Vicia sativa, Raphanus sativus, Zea mays and Sinapis alba plants were used. Except for S. alba root growth inhibition, Ni had the strongest inhibitory effect on root and shoot growth. The inhibitory rank order based on IC₅₀ values was Ni(II) > Cr(VI) > Cr(III). Z. mays was the least sensitive to all metals. While the accumulation of Cr was higher in the roots than the upper plant parts, Ni transport to shoots was at least two times higher than that of Cr. The highest accumulation of Cr was found in Z. mays and that of Ni in V. sativa and Z. mays roots. For all plants, the translocation factor was higher for Cr(VI) than for Cr(III). The translocation factor for Ni was several times higher than those of Cr. For mutagenicity assay, root tips of V. sativa, R. sativus and Z. mays were used. All metals exerted a significant increase of chromosomal aberrations and the rank order of aberrations was: Cr(VI) > Ni(II) > Cr(III). Genotoxic effects of metals were also determined by analysis of micronuclei frequency in the pollen tetrads of Tradescantia plants. None of metals significantly stimulated micronuclei frequency and the genotoxic effect decreased in the following order: Cr(VI) ≥ Ni(II) > Cr(III).

Development of near-isogenic lines and identification of markers linked to auxinic herbicide resistance in wild mustard (Sinapis arvensis L.)

BACKGROUND

Auxinic herbicides are widely used for selective control of many broadleaf weeds, e.g. wild mustard. An auxinic-herbicide-resistant wild mustard biotype may offer an excellent model system to elucidate the mechanism of action of these herbicides. Classical genetic analyses demonstrate that the wild mustard auxinic herbicide resistance is determined by a single dominant gene. Availability of near-isogenic lines (NILs) of wild mustard with auxinic herbicide resistance (R) and herbicide susceptibility (S) will help to study the fitness penalty as well as the precise characterization of this gene.

RESULTS

Eight generations of backcrosses were performed, and homozygous auxinic-herbicide-resistant and auxinic-herbicide-susceptible NILs were identified from BC(8) F(3) families. S plants produced significantly more biomass and seed compared with R plants, suggesting that wild mustard auxinic herbicide resistance may result in fitness reduction. It was also found that the serrated margin of the first true leaf was closely linked to auxinic herbicide resistance. Using the introgressed progeny, molecular markers linked to auxinic herbicide resistance were identified, and a genetic map was constructed.

CONCLUSION

The fitness penalty associated with the auxinic herbicide resistance gene may explain the relatively slow occurrence and spread of auxinic-herbicide-resistant weeds. The detection of the closely linked markers should hasten the identification and characterization of this gene.

Modeling effective dosages in hormetic dose-response studies

BACKGROUND

Two hormetic modifications of a monotonically decreasing log-logistic dose-response function are most often used to model stimulatory effects of low dosages of a toxicant in plant biology. As just one of these empirical models is yet properly parameterized to allow inference about quantities of interest, this study contributes the parameterized functions for the second hormetic model and compares the estimates of effective dosages between both models based on 23 hormetic data sets. Based on this, the impact on effective dosage estimations was evaluated, especially in case of a substantially inferior fit by one of the two models.

METHODOLOGY/PRINCIPAL FINDINGS

The data sets evaluated described the hormetic responses of four different test plant species exposed to 15 different chemical stressors in two different experimental dose-response test designs. Out of the 23 data sets, one could not be described by any of the two models, 14 could be better described by one of the two models, and eight could be equally described by both models. In cases of misspecification by any of the two models, the differences between effective dosages estimates (0-1768%) greatly exceeded the differences observed when both models provided a satisfactory fit (0-26%). This suggests that the conclusions drawn depending on the model used may diverge considerably when using an improper hormetic model especially regarding effective dosages quantifying hormesis.

CONCLUSIONS/SIGNIFICANCE

The study showed that hormetic dose responses can take on many shapes and that this diversity can not be captured by a single model without risking considerable misinterpretation. However, the two empirical models considered in this paper together provide a powerful means to model, prove, and now also to quantify a wide range of hormetic responses by reparameterization. Despite this, they should not be applied uncritically, but after statistical and graphical assessment of their adequacy.

Multimodal action and selective toxicity of zerovalent iron nanoparticles against cyanobacteria

Cyanobacteria pose a serious threat to water resources around the world. This is compounded by the fact that they are extremely resilient, having evolved numerous protective mechanisms to ensure their dominant position in their ecosystem. We show that treatment with nanoparticles of zerovalent iron (nZVI) is an effective and environmentally benign method for destroying and preventing the formation of cyanobacterial water blooms. The nanoparticles have multiple modes of action, including the removal of bioavailable phosphorus, the destruction of cyanobacterial cells, and the immobilization of microcystins, preventing their release into the water column. Ecotoxicological experiments showed that nZVI is a highly selective agent, having an EC(50) of 50 mg/L against cyanobacteria; this is 20-100 times lower than its EC(50) for algae, daphnids, water plants, and fishes. The primary product of nZVI treatment is nontoxic and highly aggregated Fe(OH)(3), which promotes flocculation and gradual settling of the decomposed cyanobacterial biomass.

Cylindrospermopsin and microcystin-LR alter the growth, development and peroxidase enzyme activity of white mustard (Sinapis alba L.) seedlings, a comparative analysis

This work focuses on the comparative analysis of the effects of two cyanobacterial toxins of different chemical structure cylindrospermopsin (CYN) and microcystin-LR (MC-LR) on the white mustard (Sinapis alba L.) seedlings. Both cyanotoxins reduced significantly the fresh mass and the length of cotyledons, hypocotyls and main roots of seedlings in a concentration dependent manner. For various mustard organs the 50% inhibitory concentration values (IC50) of growth were between 3-5 μg ml(-1) for MC-LR and between 5-10 μg ml-1 for CYN, respectively. Cyanotoxins altered the development of cotyledons, the accumulation of photosynthetically active pigments and anthocyanins. Low MC-LR concentrations (0.01 and 0.1 μg ml(-1)) stimulated anthocyanin formation in the cotyledons but higher than 1 μg ml(-1) MC-LR concentrations strongly inhibited it. The CYN treated chlorotic cotyledons were violet coloured in consequence of high level of anthocyanins, while MC-LR induced chlorosis was accompanied by the appearance of necrotic patches. Necrosis and increases of peroxidase enzyme activity (POD) are general stress responses but these alterations were characteristic only for MC-LR treated mustard plants. These findings provide experimental evidences of developmental alterations induced by protein synthesis and protein phosphatase inhibitory cyanotoxins (CYN and MC-LR) in a model dicotyledonous plant.

Inorganic materials as ameliorants for soil remediation of metal toxicity to wild mustard (Sinapis arvensis L.)

The ameliorating effects of different inorganic materials were investigated on a soil originating from a zinc smelter dumping site contaminated by toxic metals. Wild mustard (Sinapis arvensis L.) was used as a test plant. The soil was amended with different doses of mining sludge, Perferric Red Latosol (LVj), steel shots, cyclonic ash, silifertil, and superphosphate. The most effective amendments improved plant growth with 45% and reduced metal uptake by over 70% in comparison to untreated soil. Reductions in availability as estimated by BaCl2-extractable metals reached up to 90% for Zn and 65% for Cd as compared to unamended soil. These reductions were associated with lower shoot and root metal contents. Shoot Zn content was reduced from 1,369 microg g(-1) in plants grown on untreated soil to 377 microg g(-1) when grown on cyclonic ash amended soil while Cd decreased from 267 to 44 microg g(-1) in steel shots amended soil. Superphosphate addition had no ameliorating effect. On the contrary, it increased BaCl2-extractable amounts of Zn. Considering all parameters we determined, steel shots, cyclonic ash and silifertil are the most promising for remediating metal contaminated soil in the tropics. Further studies evaluating impacts, cost-effectiveness and durability of effects will be conducted.

Assessment of wastewater effluent quality in Thessaly region, Greece, for determining its irrigation reuse potential

The objective of the present study is to assess wastewater effluent quality in Thessaly region, Greece, in relation to its physicochemical and microbiological burden as well as its toxic potential on a number of organisms. Wastewater may be used for agricultural as well as for landscape irrigation purposes; therefore, its toxicity potential is quite important. Thessaly region has been chosen since this region suffers from a distinct water shortage in summer period necessitating alternative water resources. During our research, treated effluents from four wastewater treatment plants operating in the region (Larissa, Volos, Karditsa, and Tirnavos) were tested for specific physicochemical and microbiological parameters [biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity, selected metals presence (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As), and fecal coliforms' (FC) number]. The effluents were also tested for their toxicity using two different bioassays (Daphnia magna immobilization test and Phytotoxkit microbiotest). The findings were compared to relative regulations and guidelines regarding wastewater reuse for irrigation. The results overall show that secondary effluents in Thessaly region are generally acceptable for reuse for irrigation purposes according to limits set by legislation, if effective advanced treatment methods are applied prior to reuse. However, their potential toxicity should be closely monitored, since it was found that it may vary significantly in relation to season and location, when indicator plant and zooplankton organisms are used.

Environmental toxicity testing of contaminated soil based on microcalorimetry

Contaminated site assessment and monitoring requires efficient risk-management tools including innovative environmental toxicity tests. The first application of microcalorimetry for toxicity testing draw the attention to a possible new tool to increase sensitivity, to eliminate matrix effect and to study effect-mechanism. A Thermal Activity Monitor (TAM) microcalorimeter was used for measuring the heat production of various test organisms when getting in contact with sterile toxic soils. Well known bacterial (Azomonas agilis), animal (Folsomia candida) and plant test organisms (Sinapis alba) were tested for heat production. The heat response of selected testorganisms was measured in case of metal (Cu and Zn) and organic pollutant (Diesel oil, DBNPA and PCP) contaminated soils. In addition to the quantitative determination of the heat production, the mechanism of the toxic effect can be characterized from the shape of the power-time curve (slope of the curve, height and time of the maximum). In certain concentration ranges the higher the pollutant concentration of the soil the lower the maximum of the time-heat curve. At low pollutant concentrations an increased heat production was measured in case of A. agile and 20 and 200 mg Zn kg(-1) soil. The microcalorimetric testing was more sensitive in all cases than the traditional test methods. Our results showed that the microcalorimetric test method offers a new and sensitive option in environmental toxicology, both for research and routine testing.

Se(IV) phytotoxicity for monocotyledonae cereals (Hordeum vulgare L., Triticum aestivum L.) and dicotyledonae crops (Sinapis alba L., Brassica napus L.)

The phytotoxicity of Se(IV) was determined through root and shoot growth inhibition, biomass (dry (DM), fresh (FM)) production, water content, photosynthetic pigment (chlorophyll a, chlorophyll b and carotenoids) levels and Se accumulation in the roots and shoots. The sensitivities of monocotyledonae (Hordeum vulgare, Triticum aestivum) and dicotyledonae plants (Sinapis alba, Brassica napus) were also compared. Except for H. vulgare, Se(IV) inhibited root growth more than shoot growth. As for biomass production, Se reduced both FM and DM of all studied plants' roots. Although in shoots FM was decreased with increased Se concentration, DM was reduced only in monocotyledonae plants (H. vulgare, T. aestivum). No significant differences between roots and shoots were confirmed for the DM/FM relationship, except for S. alba seedlings. In all of the tested plants, except for B. napus, chlorophyll b was the strongest reduced pigment. Accumulation of Se was higher in the roots than in the shoots of all studied plants. Selenium concentration in the roots was at least 3-times higher than that in controls. Se(IV) accumulation in the shoots was not significantly different from that in controls. The exception was confirmed only for B. napus (87 mg Se(IV)l(-1)) and T. aestivum (36 mg Se(IV)l(-1)).

Photodegradation product of sulcotrione and the physiological response of maize (Zea mays) and white mustard (Sinapis alba)

One of the strategies for decreasing the consumption of herbicides consists in improving their uptake and efficiency. It was suggested that the photodegradation of herbicides due to sunlight results in a greater demand of herbicides to be introduced into the environment in order to ensure the plant protection activity. Moreover, an ecotoxicological effect of the photoproducts needs to be clarified. The physiological response of Zea mays and Sinapis alba (weed) to sulcotrione and its main photoproduct, called chromone (xanthene-1,9-dione-3,4-dihydro-6-methylsulfonyl), was evaluated under controlled conditions in a growth chamber. The dose-response effects were determined on Z. mays and S. alba. Using the sulcotrione (doses ranging from 1 to 9mg per plant), the physiological parameters indicated a decrease of photosynthesis for the S. alba species while the Z. mays species were only slightly affected. On the contrary, the chromone had no herbicide activity on both species. The sulcotrione is known to block 4-hydroxyphenyl pyruvate dioxygenase (HPPD) enzyme. The differences between the parent herbicide and the photoproduct could be ascribed to drastic structural modifications. We have shown that the chromone probably do not block the HPPD active site.

Assessment of the effects of soil PAH accumulation by a battery of ecotoxicological tests

Surface soils were collected at remote, urban and industrial sites in the Southern of Italy in order to evaluate PAH concentrations and assess the toxic effects by a battery of ecotoxicological tests. The tests were performed on whole soils and on both organic and aqueous extracts. Further goal of this study was to integrate the results coming from each test and matrix in a synthetic toxicity index. The highest summation sigmaPAH concentrations were measured at the industrial soil, although this one did not show an high ecotoxicological risk. Among the performed tests, the phytotoxicity tests showed the highest sensitivity. For whole soil, the worst case always has been represented by test through bacteria. Our results could represent the first step toward the selection of a proper battery to characterize the soil ecotoxicological risk.

Effects of elevated CO2 on intra-specific competition in Sinapis alba: an examination of the role of growth responses to red:far-red ratio

Response of plants to elevated CO2 differs markedly between individually- and competitively-grown plants, both in terms of mean size and variation about the mean. Using Sinapis alba, we explored whether these contrasting effects are a consequence of the effect of competition on the red:far red (R:FR) light ratio. Plants were grown at both ambient and elevated (700 microl.l(-1)) CO2 in competitive stands, and as individuals at either a low (0.7) or high (1.25) R:FR ratio at a constant photosynthetic photon fluence rate. Elevated CO2 increased stand biomass by enhancing the growth of canopy dominants, but not the subordinates. As a consequence, elevated CO2 increased the coefficient of variation in size within the stands. Elevated CO2 did not enhance the growth of individually-grown plants at the low R:FR ratio, but did at the high R:FR ratio. Both the poor response of subordinate plants to elevated CO2 and the increased size inequalities of individuals within the stand can be explained in terms of the effect of the R:FR ratio on CO2 responsiveness. The effect of the R:FR ratio on CO2 response may be related to its effect on allocation patterns and nutrient uptake.

Impact of sunflower (Helianthus annuus L.) extracts upon reserve mobilization and energy metabolism in germinating mustard (Sinapis alba L.) seeds

One commonly observed effect of phytotoxic compounds is the inhibition or delay of germination of sensitive seeds. Mustard (Sinapis alba L.) seeds were incubated with aqueous extracts of sunflower (Helianthus annuus L.) leaves. Although sunflower phytotoxins did not influence seed viability, extracts completely inhibited seed germination. Inhibition of germination was associated with alterations in reserve mobilization and generation of energy in the catabolic phase of germination. Degradation of lipids was suppressed by sunflower foliar extracts resulting in insufficient carbohydrate supply. The lack of respiratory substrates and decrease in energy (ATP) generation resulted in suppression of the anabolic phase of seed germination and ultimately growth inhibition.

Comparison of bioassays by testing whole soil and their water extract from contaminated sites

The harmful effects of contaminants on the ecosystems and humans are characterised by their environmental toxicity. The aim of this study was to assess applicability and reliability of several environmental toxicity tests, comparing the result of the whole soils and their water extracts. In the study real contaminated soils were applied from three different inherited contaminated sites of organic and inorganic pollutants. The measured endpoints were the bioluminescence inhibition of Vibrio fischeri (bacterium), the dehydrogenase activity inhibition of Azomonas agilis (bacterium), the reproduction inhibition of Tetrahymena pyriformis (protozoon), and Panagrellus redivivus (nematode), the mortality of Folsomia candida (springtail), the root and shoot elongation inhibition of Sinapis alba (plant: white mustard) and the nitrification activity inhibition of an uncontaminated garden soil used as "test organism". Besides the standardised or widely used methods some new, direct contact ecotoxicity tests have been developed and introduced, which are useful for characterisation of the risk of contaminated soils due to their interactive nature. Soil no. 1 derived from a site polluted with transformer oil (PCB-free); Soil no. 2 originated from a site contaminated with mazout; Soil no. 3 was contaminated with toxic metals (Zn, Cd, Cu, Pb, As). In most cases, the interactive ecotoxicity tests indicated more harmful effect of the contaminated soil than the tests using soil extracts. The direct contact environmental toxicity tests are able to meet the requirements of environmental toxicology: reliability, sensibility, reproducibility, rapidity and low cost.

Comparison of the Phytotoxkit microbiotest and chemical variables for toxicity evaluation of sediments

The main objective of the research was to evaluate the suitability of the Phytotoxkit microbiotest as a tool for hazard assessment of sediments. The concentrations of oil derivatives, polycyclic aromatic hydrocarbons (PAHs), and heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were determined in sediment samples collected from the urban canal in Opole (Poland), in order to obtain a general insight of the level of sediment contamination. Phytotoxicity of sediments was estimated on the basis of seed germination and root elongation measurements, combined into an overall germination index (GI). The results revealed spatial and vertical differentiation in sediment contamination. A good correlation was obtained between organic matter content and the concentrations of particular sediment pollutants. Values of correlation coefficients at P < 0.05 ranged from 0.3246 for oil derivatives to 0.8929 for PAHs. Phytotoxicity tests, carried out on the monocotyl Sorghum saccharatum and the dicotyls Sinapis alba and Lepidium sativum, showed different responses of the three plant species to sediment samples ranging from growth inhibition to growth stimulation. The GI values revealed the following increasing order of plant sensitivity to contaminated sediments: L. sativum < S. alba < S. saccharatum. The study demonstrated that the Phytotoxkit microbiotest was effective in identifying toxic samples. However, sediment organic matter content and grain-size distribution had a significant impact on both sediment contamination and higher plantresponses to contaminated samples. The implication of these findings are discussed.

Cuticular uptake of xenobiotics into living plants. Part 2: influence of the xenobiotic dose on the uptake of bentazone, epoxiconazole and pyraclostrobin, applied in the presence of various surfactants, into Chenopodium album, Sinapis alba and Triticum aestivum leaves

This study has determined the uptake of three pesticides, applied as commercial or model formulations in the presence of a wide range of surfactants, into the leaves of three plant species (bentazone into Chenopodium album L. and Sinapis alba L., epoxiconazole and pyraclostrobin into Triticum aestivum L.). The results have confirmed previous findings that the initial dose (nmol mm(-2)) of xenobiotic applied to plant foliage is a strong, positive determinant of uptake. This held true for all the pesticide formulations studied, although surfactant concentration was found to have an effect. The lower surfactant concentrations studied showed an inferior relationship between the amount of xenobiotic applied and uptake. High molecular mass surfactants also produced much lower uptake than expected from the dose uptake equations in specific situations.