6-Ethoxy-4- N-(2-morpholin-4-ylethyl) -2-N-propan-2-yl-1,3, 5-triazine-2, 4-diamine endows herbicidal activity against Phalaris minor a weed of wheat crop field: An in -silico and experimental approaches of herbicide discovery.

Phalaris minor is a major weed of wheat crop which has evolved resistance against herbicides. Isoproturon is the most accepted herbicide developed resistance in 1992. Later, introduced herbicides also developed resistance and cross-resistance to their respective binding sites. Isoproturon binds at the QB binding site of the D1 protein of photosystem-II (PS-II), which blocks the electron transfer in photosynthesis. In this work, we have carried out a series of computational studies to prioritize the promising herbicides against D1 protein of P. minor. Through the computational studies, twenty-four lead molecules are prioritized which have shown a higher binding affinity and inhibition constant than the reference ligand molecule. The binding and conformational stability of docked complexes was evaluated by molecular dynamics simulations and binding free energy calculations i.e., MM/PBSA. A list of amino acids such as Ala225, Ser226, Phe227, and Asn229 present in the binding site of protein is obtained to be playing an important role in the stability of the protein-lead complex via hydrogen bond and π-π interactions. Binding free energy calculation revealed that the selected lead molecule binding is energetically favorable and driven by electrostatic interactions. Among 24 leads, computational results have uncovered eight promising compounds as potential herbicides which have shown comparable physiochemical profile, better docking scores, system stability, H-bond occupancy, and binding free energy than terbutryn, a reference molecule. These prioritized molecules were custom synthesized and evaluated for their herbicidal activity and specificity through whole plant assay under laboratory-controlled conditions. The lead molecule ELC5 (6-ethoxy-4-N-(2-morpholin-4-ylethyl)-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine) has shown comparable activity to the reference herbicide(isoproturon) against P. minor.

Water use efficiency and shoot biomass production under water limitation is negatively correlated to the discrimination against 13C in the C3 grasses Dactylis glomerata, Festuca arundinacea and Phalaris arundinacea.

Climate change impacts rainfall patterns which may lead to drought stress in rain-fed agricultural systems. Crops with higher drought tolerance are required on marginal land with low precipitation or on soils with low water retention used for biomass production. It is essential to obtain plant breeding tools, which can identify genotypes with improved drought tolerance and water use efficiency (WUE). In C3 plant species, the variation in discrimination against 13C (Δ13C) during photosynthesis has been shown to be a potential indicator for WUE, where discrimination against 13C and WUE were negatively correlated. The aim of this study was to determine the variation in the discrimination against 13C between species and cultivars of three perennial C3 grasses (Dactylis glomerata (cocksfoot), Festuca arundinacea (tall fescue) and Phalaris arundinacea (reed canary grass)) and test the relationships between discrimination against 13C, season-long water use WUEB, shoot and root biomass production in plants grown under well-watered and water-limited conditions. The grasses were grown in the greenhouse and exposed to two irrigation regimes, which corresponded to 25% and 60% water holding capacity, respectively. We found negative relationships between discrimination against 13C and WUEB and between discrimination against 13C and shoot biomass production, under both the well-watered and water-limited growth conditions (p < 0.001). Discrimination against 13C decreased in response to water limitation (p < 0.001). We found interspecific differences in the discrimination against 13C, WUEB, and shoot biomass production, where the cocksfoot cultivars showed lowest and the reed canary grass cultivars highest values of discrimination against 13C. Cocksfoot cultivars also showed highest WUEB, shoot biomass production and potential tolerance to water limitation. We conclude that discrimination against 13C appears to be a useful indicator, when selecting C3 grass crops for biomass production under drought conditions.

The use of reed canary grass and giant miscanthus in the phytoremediation of municipal sewage sludge.

The application of municipal sewage sludge on energy crops is an alternative form of recycling nutrients, food materials, and organic matter from waste. Municipal sewage sludge constitutes a potential source of heavy metals in soil, which can be partially removed by the cultivation of energy crops. The aim of the research was to assess the effect of municipal sewage sludge on the uptake of heavy metals by monocotyledonous energy crops. Sewage sludge was applied at doses of 0, 10, 20, 40, and 60 Mg DM · ha(-1) once, before the sowing of plants. In a 6-year field experiment, the effect of four levels of fertilisation with sewage sludge on the uptake of heavy metals by two species of energy crops, reed canary grass (Phalaris arundinacea L.) of 'Bamse' cultivar and giant miscanthus (Miscanthus × giganteus GREEF et DEU), was analysed. It was established that the increasing doses of sewage sludge had a considerable effect on the increase in biomass yield from the tested plants. Due to the increasing doses of sewage sludge, a significant increase in heavy metals content in the energy crops was recorded. The heavy metal uptake with the miscanthus yield was the highest at a dose of 20 Mg DM · ha(-1), and at a dose of 40 Mg DM · ha(-1) in the case of reed canary grass. Research results indicate that on account of higher yields, higher bioaccumulation, and higher heavy metal uptake, miscanthus can be selected for the remediation of sewage sludge.

Ile-1781-Leu and Asp-2078-Gly Mutations in ACCase Gene, Endow Cross-resistance to APP, CHD, and PPZ in Phalaris minor from Mexico.

Herbicides that inhibit acetyl coenzyme A carboxylase (ACCase) are commonly used in Mexico to control weedy grasses such as little seed canarygrass (Phalaris minor). These herbicides are classified into three major families (ariloxyphenoxypropionates (APP), cyclohexanodiones (CHD), and, recently, phenylpyrazolines (PPZ)). In this work, the resistance to ACCase (APP, CHD, and PPZ) inhibiting herbicides was studied in a biotype of Phalaris minor (P. minor) from Mexico, by carrying out bioassays at the whole-plant level and investigating the mechanism behind this resistance. Dose-response and ACCase in vitro activity assays showed cross-resistance to all ACCase herbicides used. There was no difference in the absorption, translocation, and metabolism of the (14)C-diclofop-methyl between the R and S biotypes. The PCR generated CT domain fragments of ACCase from the R biotype and an S reference were sequenced and compared. The Ile-1781-Leu and Asp-2078-Gly point mutations were identified. These mutations could explain the loss of affinity for ACCase by the ACCase-inhibing herbicides. This is the first report showing that this substitution confers resistance to APP, CHD, and PPZ herbicides in P. minor from Mexico. The mutations have been described previously only in a few cases; however, this is the first study reporting on a pattern of cross-resistance with these mutations in P. minor. The findings could be useful for better management of resistant biotypes carrying similar mutations.

Plasticity of nitrogen allocation in the leaves of the invasive wetland grass, Phalaris arundinacea and co-occurring Carex species determines the photosynthetic sensitivity to nitrogen availability.

Phalaris arundinacea displaces the slower-growing, native sedge, Carex stricta, where nitrogen availability is high. Our aim was to address whether morphological and physiological traits associated with carbon gain for P. arundinacea and C. stricta responded to nitrogen supply differently and if the species exhibited different degrees of plasticity in these traits. The plants were grown in gravel and provided modified Hoagland's solution containing four nitrogen concentrations from 0.15 to 15 mM for 6 to 7 weeks. Supplied nitrogen affected the leaf nitrogen content to the same degree for both species. Increasing supplied nitrogen strongly increased CO2 assimilation (A), photosynthetic nitrogen use efficiency (PNUE), and respiration for P. arundinacea but had only a small effect on these parameters for C. stricta. Relative to growth at 15 mM nitrogen, growth at 0.15 mM for young leaves decreased carboxylation capacity and efficiency and the capacity for electron transport for P. arundinacea and a larger, stouter Carex species, Carex lacustris, by 53 to 70% but only 20 to 24% for C. stricta. Leaf nitrogen decreased approximately 50% for all species, but vacuolar nitrate did not decrease for P. arundinacea and C. stricta, suggesting that it does not serve as a nitrogen reserve for use during nitrogen deprivation in these species. After 4 months of nitrogen deprivation, P. arundinacea doubled A in 12 days after being supplied 15 mM nitrogen, whereas A for C. stricta increased only 22%. We propose that one factor linking P. arundinacea abundance to nitrogen availability involves this species' plastic response of carbon gain to nitrogen supply. C. stricta appears to be adapted to tolerate low nitrogen availability but cannot respond as rapidly and extensively as P. arundinacea when nitrogen supply is high.

Isolation of the P5CS gene from reed canary grass and its expression under salt stress.

Reed canary grass (RCG) is a perennial grass traditionally cultivated for forage. It is also used as fuel to produce energy in Finland and Sweden, and other countries have expressed interest in the cultivation of RCG. In China, arable land is limited. Salinity is considered to be a major factor limiting plant crop development and productivity. To boost biofuel production of RCG and extend its range in saline soil, we seek to improve its salt tolerance. Proline acts as an osmolyte that accumulates when plants are subjected to abiotic stress. P5CS plays a crucial role in proline biosynthesis. We isolated a P5CS gene from RCG, designated B231P5CS (GenBank accession No. JQ622685). B231P5CS is a fragment (971 bp) that encodes a 323-amino acid polypeptide. We also cloned an actin gene fragment from RCG as a reference gene in expression analysis of B231P5CS gene. Expression analysis revealed that B231P5CS transcripts were upregulated in leaves after treatment with salt (200 mM NaCl) and that transcript levels of B231P5CS reached a maximum 12 h after exposure, which was 14.69 times the level in control plants. The trends of expression were exactly opposite in roots; transcripts were downregulated after salt treatment. Proline concentration increased in leaves after stress. In contrast, proline content of roots decreased up to 3.6-fold relative to controls. Changes in proline concentration after stress were correlated with B231P5CS expression. Our results suggest that B231P5CS is a stress-inducible gene and plays a non-redundant role in plant development. This gene may be used to improve stress tolerance of RGC and other bioenergy feedstock.

Accumulation and distribution of macroelements in the organs of Phalaris arundinacea L.: Implication for phytoremediation.

The aim of this study was to assess nutrient and alkali metal accumulation and their distribution in the organs of Phalaris arundinacea and relations between environmental macroelement concentrations and accumulation in plant tissues. The content of N, P, K, Ca, Mg and Na in water, bottom sediments and different organs of Phalaris arundinacea from the Bystrzyca River (Lower Silesia) was determined. The organs of the reed canary grass contained relatively high amounts of macroelements and differed significantly in their accumulation. All macroelements other than Na were accumulated in the highest amounts in aboveground, photosynthetic tissues. Phalaris arundinacea is an Na and Ca excluder plant and an N, P, Mg and K accumulator. Transport efficiency from bottom sediments to plant roots was higher than between plant organs. Nitrogen, P and K are taken up actively while Ca passively. The high translocation ratio of nutrients, particularly for Ca, Mg, K and N, makes the reed canary grass suitable for nutrient phytoextraction from water and bottom sediments of eutrophic lakes and rivers. Bottom sediments can be considered the primary source of Ca for Phalaris arundinacea.

Comparison of biogas production from wild and cultivated varieties of reed canary grass.

The chemical composition and efficiency of biogas production in the methane fermentation process of silages of wild and cultivated varieties of reed canary grass were compared. An attempt was made to answer the question on how the habitat and the way of utilization of plants affect chemical composition and biogas yield. Physicochemical properties such as dry matter, organic dry matter, protein, fat, crude fiber fraction, macro- and microelements content were considered. The anaerobic digestion process and FTIR analysis were also carried out. The results showed that the two varieties differ essentially in their physical and chemical properties. The cultivated variety was characterized by higher biogas yield (406Ndm(3)kg(-1) VS) than the wild one (120Ndm(3)kg(-1) VS). This was probably related to the chemical composition of plants, especially the high content of indigestible crude fiber fractions and ash. These components could reduce biogas quantity and quality.

Chemical composition and methane yield of reed canary grass as influenced by harvesting time and harvest frequency.

This study examined the influence of harvest time on biomass yield, dry matter partitioning, biochemical composition and biological methane potential of reed canary grass harvested twice a month in one-cut (OC) management. The regrowth of biomass harvested in summer was also harvested in autumn as a two-cut management with (TC-F) or without (TC-U) fertilization after summer harvest. The specific methane yields decreased significantly with crop maturity that ranged from 384 to 315 and from 412 to 283 NL (normal litre) (kgVS)(-1) for leaf and stem, respectively. Approximately 45% more methane was produced by the TC-F management (5430Nm(3)ha(-1)) as by the OC management (3735Nm(3)ha(-1)). Specific methane yield was moderately correlated with the concentrations of fibre components in the biomass. Larger quantity of biogas produced at the beginning of the biogas assay from early harvested biomass was to some extent off-set by lower concentration of methane.

Reed canary grass as a feedstock for 2nd generation bioethanol production.

The enzymatic hydrolysis and fermentation of reed canary grass, harvested in the spring or autumn, and barley straw were studied. Steam pretreated materials were efficiently hydrolysed by commercial enzymes with a dosage of 10-20FPU/g d.m. Reed canary grass harvested in the spring was hydrolysed more efficiently than the autumn-harvested reed canary grass. Additional ß-glucosidase improved the release of glucose and xylose during the hydrolysis reaction. The hydrolysis rate and level of reed canary grass with a commercial Trichoderma reesei cellulase could be improved by supplementation of purified enzymes. The addition of CBH II improved the hydrolysis level by 10% in 48hours' hydrolysis. Efficient mixing was shown to be important for hydrolysis already at 10% dry matter consistency. The highest ethanol concentration (20g/l) and yield (82%) was obtained with reed canary grass at 10% d.m. consistency.

Cd, Cu and Zn mobility in contaminated sediments from an infiltration basin colonized by wild plants: the case of Phalaris arundinacea and Typha latifolia.

Infiltration basins are shallow reservoirs in which stormwater is temporarily collected in order to reduce water volume in downstream networks. The settling of stormwater particles leads to a contaminated sediment layer. Wild plants can colonize these basins and can also play a role on the fate of heavy metals either directly by their uptake or indirectly by modification of physico-chemical characteristics of the sediment and therefore by modification of the mobility of heavy metals. The aim of this study, carried out in a vegetated infiltration basin, is to assess Cd, Cu and Zn mobility in two zones colonized by different species, Phalaris arundinacea and Typha latifolia. The study was carried out using three single chemical extractions: CaCl2 for the exchangeable phase, acetate buffer for the acido-soluble fraction and diethylenetriamine-pentaacetic acid (DTPA) for the fraction associated to the organic matter. Zn and Cd are mainly associated to carbonated and organic matter phases of the sediment. Moreover, acetate buffer-extractable Zn contents are strongly correlated to carbonates content in the sediment. DTPA-extractable Cu contents are strongly correlated with organic carbon sediment contents. We have also noted that extractable contents were significantly different between both zones whatever the metal.

Greater seasonal carbon gain across a broad temperature range contributes to the invasive potential of Phalaris arundinacea (Poaceae; reed canary grass) over the native sedge Carex stricta (Cyperaceae).

PREMISE OF THE STUDY: Most invasive plants grow faster and produce more biomass than the species that they displace, but physiological mechanisms leading to invasive success are poorly understood. To foster novel control approaches, our goal was to determine whether the grass Phalaris arundinacea possessed superior physiological strategies that contributed to its success over native sedges. METHODS: Data for spring, summer, and autumn diel gas-exchange, leaf morphology, and nitrogen content for plants of P. arundinacea and Carex stricta in water-saturated, drained, and periodically flooded sites in northern Indiana, USA, were compared with similar data for plants in a greenhouse. KEY RESULTS: Phalaris arundinacea had higher maximum CO(2) assimilation (A) across a broad range of temperatures, greater summer/autumn net carbon gain, higher water use efficiencies, larger leaf areas per shoot, and higher specific leaf areas than did C. stricta. Species differences in gas-exchange data were similar in the greenhouse. However, long-term flooding reduced A for P. arundinacea. Greater declines in leaf A and nitrogen content from July to October compared to P. arundinacea were suggestive of earlier leaf senescence for C. stricta. CONCLUSIONS: We propose that superior daily and seasonal carbon gain, especially during rhizome carbohydrate storage in the summer and autumn, contribute to the success of invasive P. arundinacea over C. stricta. This advantage may be enhanced by frequent summer/autumn heat waves. The poor performance of P. arundinacea during long-term flooding is consistent with C. stricta's dominance in water-saturated soil, implying that water management strategies could be crucial to controlling P. arundinacea.

Mine wastewater treatment using Phalaris arundinacea plant material hydrolyzate as substrate for sulfate-reducing bioreactor.

A low-cost substrate, Phalaris arundinacea was acid hydrolyzed (Reed Canary Grass hydrolyzate, RCGH) and used to support sulfate reduction. The experiments included batch bottle assays (35 degrees C) and a fluidized-bed bioreactor (FBR) experiment (35 degrees C) treating synthetic mine wastewater. Dry plant material was also tested as substrate in batch bottle assays. The batch assays showed sulfate reduction with the studied substrates, producing 540 and 350mgL(-1) dissolved sulfide with RCGH and dry plant material, respectively. The soluble sugars of the RCGH presumably fermented into volatile fatty acids and hydrogen, which served as electron donors for sulfate reducing bacteria. A sulfate reduction rate of 2.2-3.3gL(-1)d(-1) was obtained in the FBR experiment. The acidic influent was neutralized and the highest metal precipitation rates were 0.84g FeL(-1)d(-1) and 15mg ZnL(-1)d(-1). The sulfate reduction rate in the FBR was limited by the acetate oxidation rate of the sulfate-reducing bacteria.

How nitrogen and sulphur addition, and a single drought event affect root phosphatase activity in Phalaris arundinacea.

Conservation and restoration of fens and fen meadows often aim to reduce soil nutrients, mainly nitrogen (N) and phosphorus (P). The biogeochemistry of P has received much attention as P-enrichment is expected to negatively impact on species diversity in wetlands. It is known that N, sulphur (S) and hydrological conditions affect the biogeochemistry of P, yet their interactive effects on P-dynamics are largely unknown. Additionally, in Europe, climate change has been predicted to lead to increases in summer drought. We performed a greenhouse experiment to elucidate the interactive effects of N, S and a single drought event on the P-availability for Phalaris arundinacea. Additionally, the response of plant phosphatase activity to these factors was measured over the two year experimental period. In contrast to results from earlier experiments, our treatments hardly affected soil P-availability. This may be explained by the higher pH in our soils, hampering the formation of Fe-P or Fe-Al complexes. Addition of S, however, decreased the plants N:P ratio, indicating an effect of S on the N:P stoichiometry and an effect on the plant's P-demand. Phosphatase activity increased significantly after addition of S, but was not affected by the addition of N or a single drought event. Root phosphatase activity was also positively related to plant tissue N and P concentrations, plant N and P uptake, and plant aboveground biomass, suggesting that the phosphatase enzyme influences P-biogeochemistry. Our results demonstrated that it is difficult to predict the effects of wetland restoration, since the involved mechanisms are not fully understood. Short-term and long-term effects on root phosphatase activity may differ considerably. Additionally, the addition of S can lead to unexpected effects on the biogeochemistry of P. Our results showed that natural resource managers should be careful when restoring degraded fens or preventing desiccation of fen ecosystems.

Utilization of kura clover-reed canarygrass silage versus alfalfa silage by lactating dairy cows.

The mixture of kura clover (Trifolium ambiguum M. Bieb.) and reed canarygrass (Phalaris arundinacea L.) has proven to be extremely persistent in the northern United States, but information about dairy cow performance on this mixture is lacking. Twenty lactating Holstein cows were used in a crossover design to compare dry matter (DM) intake and milk production from diets containing kura clover-reed canarygrass silage (KRS) or alfalfa (Medicago sativa L.) silage (AS). Forages were cut, wilted, ensiled in horizontal plastic bags, and allowed to ferment for at least 50 d before beginning the feeding experiment. The KRS was approximately 40% kura clover and 60% reed canarygrass. Treatments were total mixed rations formulated with either 57% of total DM from 1) AS or 2) KRS. Experimental periods were 28 d, with the first 14 d for diet adaptation and the last 14 d for measurement of intake and milk production. The neutral detergent fiber (NDF) concentrations of AS and KRS were 37.3 and 47.3%, respectively. The fermentation analyses indicated that both silages underwent a restricted fermentation, producing primarily lactic acid and some acetic acid. Dry matter intake (24.2 vs. 22.8 kg) and 4% fat-corrected milk (32.8 vs. 30.9 kg) were significantly higher for cows fed AS than for cows fed KRS. Cows consumed less NDF (6.7 vs. 8.0 kg) and less digestible NDF (3.0 vs. 4.4 kg) when fed AS diets compared with KRS diets, but the pool of ruminally undegraded NDF was similar (3.7 kg) between diets. Cows produced 1.5 kg of milk/kg of DM consumed regardless of the diet, indicating that digestible NDF of KRS was utilized with similar efficiency as the cell wall constituents of AS, but the intake of cows fed KRS may have been limited by rumen fill. Milk fat concentration tended to be higher for cows fed AS, but the milk true protein concentration and yields of fat and protein did not differ by treatment. Milk urea nitrogen content was higher when cows consumed AS (16.4 mg/ dL) compared with KRS (13.4 mg/dL). The cows fed KRS consumed more NDF but less total DMI, based on the results from this trial with diets formulated to contain approximately 60% of DM as forage, resulting in slightly lower milk yields than cows fed excellent-quality AS. This grass-legume mixture has the potential to be a source of quality forage for dairy cows in regions where alfalfa persistence is a problem.

Life-cycle assessment of net greenhouse-gas flux for bioenergy cropping systems.

Bioenergy cropping systems could help offset greenhouse gas emissions, but quantifying that offset is complex. Bioenergy crops offset carbon dioxide emissions by converting atmospheric CO2 to organic C in crop biomass and soil, but they also emit nitrous oxide and vary in their effects on soil oxidation of methane. Growing the crops requires energy (e.g., to operate farm machinery, produce inputs such as fertilizer) and so does converting the harvested product to usable fuels (feedstock conversion efficiency). The objective of this study was to quantify all these factors to determine the net effect of several bioenergy cropping systems on greenhouse-gas (GHG) emissions. We used the DAYCENT biogeochemistry model to assess soil GHG fluxes and biomass yields for corn, soybean, alfalfa, hybrid poplar, reed canarygrass, and switchgrass as bioenergy crops in Pennsylvania, USA. DAYCENT results were combined with estimates of fossil fuels used to provide farm inputs and operate agricultural machinery and fossil-fuel offsets from biomass yields to calculate net GHG fluxes for each cropping system considered. Displaced fossil fuel was the largest GHG sink, followed by soil carbon sequestration. N20 emissions were the largest GHG source. All cropping systems considered provided net GHG sinks, even when soil C was assumed to reach a new steady state and C sequestration in soil was not counted. Hybrid poplar and switchgrass provided the largest net GHG sinks, >200 g CO2e-C x m(-2) x yr(-1) for biomass conversion to ethanol, and >400 g CO2e-C x m(-2) x yr(-1) for biomass gasification for electricity generation. Compared with the life cycle of gasoline and diesel, ethanol and biodiesel from corn rotations reduced GHG emissions by approximately 40%, reed canarygrass by approximately 85%, and switchgrass and hybrid poplar by approximately 115%.

Trace metals in Phragmites australis and Phalaris arundinacea growing in constructed and natural wetlands.

Constructed wetlands with horizontal subsurface flow (HF CWs) designed for treatment of municipal sewage have been monitored extensively with respect to removal of organics, suspended solids, nitrogen, phosphorus and bacteria. However, the information on the removal of various metals and metalloids in these systems is very limited. During the period 2002-2004 aboveground and belowground biomass of Phragmites australis (common reed) and Phalaris arundinacea (reed canarygrass) were sampled in three HF CWs in the Czech Republic. Concentrations of monitored elements in both aboveground and belowground plant tissues were similar to those found in plants growing in natural stands. The concentrations were much lower as compared to those found in plants growing in wetlands receiving acid mine drainage waters, waters from smelters or highway runoff. Concentrations decrease in the order of roots>rhizomes>leaves>stems. The leaf:stem concentration ratios were quite similar for all monitored elements ranging between 1.0 and 1.9. The root:leaf concentration ratio varied widely between 1.5 (Cu) and 54 (Cr) with a mean value of 20.0. Belowground/aboveground plant tissue concentration ratios varied from 2.2 (Cu) to 32 (Cr) with the average value of 9.9.

PCDD/F in source-sorted waste fractions and emissions from their co-combustion with reed canary-grass.

The dry combustible fraction of source-sorted household waste, including material that would otherwise be recycled, was mixed with the energy crop reed canary-grass (Phalaris arundinacea L.), and combusted as briquettes in 150 and 600 kW biofuel-boilers without advanced cleaning systems. The source-sorted waste was further sorted and characterized according to its material and chemical contents. The bulk of the waste's chlorine content came from the non-package plastic fraction, whereas 90-95% of summation operator PCDD/F (74-90% of WHO-TEQ) originated from the textile fraction. The sources of the dioxins in the waste fractions are discussed. The balance of dioxin levels was negative, i.e., the amounts of dioxins output in the flue gas were lower than those input in the fuel, except when there were operational disturbances in the combustion. In one of the combustion trials the total levels of dioxins in the flue-gas and ashes were also lower than the input levels. The use of additional cleaning equipment will be needed to ensure that emissions of dioxins and hydrochloric acid will be below legal limits.

Induction of glutathione S-transferase and glutathione by toxic compounds and elicitors in reed canary grass.

Treatment of read canary grass leaves with phenol, 4-chlorophenol, naphthalic anhydride and phenylethylisothiocyanate increased glutathione S-transferase activity by 1.4-2.4-fold (control 17 U g(-1) DW). Benzothiadiazole, beta-aminobutyric acid and salicylic acid increased activity by 1.3-1.8-fold. Total glutathione pool was increased by the toxic compounds by 1.2-2-fold and by the elicitors 1.4-1.6-fold (control 593 nmol g(-1) DW). Unlike the other compounds, benzothiadiazole and salicylic acid did not decrease the redox state. Benzothiadiazole acted synergistically with chlorophenol on glutathione S-transferase and glutathione levels and counteracted the decrease in redox state caused by the xenobiotic. Reed canary grass thus has a strong potential to neutralize toxic compounds, which may be further enhanced by elicitors.

Melatonin acts as a growth-stimulating compound in some monocot species.

In a recent study melatonin (N-acetyl-5-methoxytryptamine), a well-investigated animal molecule but minimally studied in plants, was seen to have a physiological role as growth-promoting molecule in lupin hypocotyls. In the present study, the role of melatonin as a growth promoter is extended to coleoptiles of canary grass, wheat, barley and oat, in which it shows a relative auxinic activity [with respect to indole-3-acetic acid (IAA), the main auxin in plants] of between 10 and 55%. In addition, melatonin is seen to have an important inhibitory growth effect on roots similar to that played by auxin. The quantitation by liquid chromatography with electrochemical detection and identification by tandem mass spectrometry of melatonin and IAA in etiolated coleoptiles of the monocots assayed showed that both compounds are present in similar levels in these tissues. These results point to the co-existence of auxin and melatonin in tissues and raises the possibility of their co-participation in some physiological actions as auxinic hormones in plants.