Effects of cyanobacteria producing microcystins on seed germination and seedling growth of several agricultural plants

The effects of cyanobacteria aqueous extracts containing Microcystin-LR (MC-LR) on the seed germination and growth of Pisum sativum, Lens esculenta, Zea mays and Triticum durum were investigated. Experiments were carried out on a range of doses of the extract (equivalent to 0, 1.6, 2.9, 5.8, 8.7 and 11.6 μ g MC-LR/mL). The results confirm that these plants were sensitive to cell-free extracts of a toxic Microcystis and that germination inhibition was dose dependent. One-way analysis of variance (ANOVA) showed that P. sativum is the most sensitive tested species with a 97% germination rate reduction and L. esculenta was the most resistant. At the 8th day, the exposure to the microcystins (MC) resulted in a significant decrease of plant epicotyls length, roots length and a net inhibition of lateral root formation. It is concluded that MC could affect also terrestrial plants seedling germination and growth. Therefore, the use of water for irrigation contaminated by MC could exert negative biochemical effects on seed and plant metabolism which might influence the agricultural crops.     

Ecotoxicological effects of cadmium on three ornamental plants

Ecotoxicological effects of cadmium (Cd) on three ornamental plants African marigold (Tagetes erecta), scarlet sage (Salvia splendens) and sweet hibiscus (Abelmoschus manihot) were investigated. Seeds of these plants were exposed to five different concentrations of Cd (0-50 mgl(-1)). Ecotoxicological indexes based on inhibition rate (IC) of seed germination, root and shoot elongation, biomass (fresh weight and dry weight), as well as IC50 (Cd concentration when 50% plants show inhibition) and tolerance indexes (the ratio of maximum root length in an experimental group to that in a control group) were determined. The results indicated that Cd had little effects (p>0.05) on seed germination of the three plants and shoot elongation of scarlet sage (S. splendens). Cadmium had significant (p<0.05) inhibitory effects on root elongation of the three plants and shoot elongation of African marigold (T. erecta). The fresh weight biomass of scarlet sage (S. splendens) was most sensitive to Cd, while that of sweet hibiscus (A. manihot) was least sensitive. On a dry weight basis, African marigold (T. erecta) was the least sensitive, and scarlet sage (S. splendens) was the most sensitive to Cd. Based on IC50 of seed germination, sweet hibiscus (A. manihot) was the most insensitive plant with an IC50 value as high as 428.0 gl(-1). According to Cd-tolerance indexes under the same Cd concentration, sweet hibiscus (A. manihot) was the most tolerant plant whereas scarlet sage (S. splendens) was the most sensitive one.     

Effects of composting on phytotoxicity of spent pig-manure sawdust litter

The phytotoxicity of spent pig-manure sawdust litter (spent litter) was evaluated during further composting. Aqueous extracts of the spent litter were prepared by shaking the sample with water (1:10 w/v), and the toxicity of these extracts was determined on relative seed germination, relative root elongation and germination index (GI, a factor of relative seed germination and relative root elongation). The sensitivity of six plant species, namely Brassica parachinensis (Chinese cabbage), Brassica albogalera (Chinese kale), Allium sativum (onion), Cucumis sativus (cucumber), Amaranthus espinosus (Chinese spinach), and Lycopersicon esculentum (tomato) were compared. The effect of different moisture levels during composting on the phytotoxicity of the spent litter was also examined. Phytotoxicity of the spent litter was only evident during the earlier stage of composting (first 14 days) and, that seed germination and root elongation reached 100% (same as the control) towards the end of the composting. The concentrations of the major inhibitors, water-extractable Cu and Zn, and NH4(+)-N of the spent litter, declined during composting, indicating that these inhibitors were gradually eliminated as composting proceeded. Multiple regression analysis showed that the NH4(+)-N content of the spent litter was the most important chemical factor affecting phytotoxicity of the plant species selected for this study. Relative root elongation and GI were more sensitive indicators of phytotoxicity than seed germination. In the present study, the GI's of all plant species were >80% at day 60, indicating that the spent litter had reached its maturation by day 60. The responses of different plant species to the water-extracts of the spent litter were different. Among the six species, Chinese cabbage and Chinese spinach were the most sensitive species, and tomato and cucumber were the least sensitive species to indicate phytotoxicity of the spent litter. Moisture adjustment during the composting process did not affect the results of the phytotoxicity test.     

Evaluation and refinement of a continuous seed germination and early seedling growth test for the use in the ecotoxicological assessment of soils.

Four higher plant species (Avena sativa L., oat; Lepidium sativum L., cress; Brassica rapa Metzg., turnip; and Phaseolus vulgaris L., bush bean) and 15 soils including five mineral oil-contaminated soils were tested to assess a soil-based continuous seed germination and early seedling growth bioassay. Seed germination was recorded and the shoot biomass of 14-day seedlings measured. An automatic self-watering system was compared with the daily hand watering. Results obtained from this study show that the self-watering system had minor effects on both seed germination and early seedling growth, and that soil nutrient status rather than soil texture significantly affected both seedling emergence and shoot biomass. Proportional dilution of suspicious samples from primary tests with an appropriate control soil is recommended for secondary tests. Shoot biomass is a more sensitive measurement endpoint than seed germination. Bush bean should not be recommended for use due to its low sensitivity to mineral oil and poor germination in soil.     

Effect of DDT on plant mineral nutrition

DDT added to soil at a concentration of 50 microg g(-1) had no inhibitory effects on germination and plant growth of barley, mung and rice, but considerably inhibited the oilseed species tested in the laboratory. The uptake of one or other ions was affected in varying degrees, with plants grown in DDT-treated soils. Detailed field studies of a peanut crop further confirmed the inhibition of ion uptake with DDT, especially Ca(2+) and K(+). Reduced uptake of (86)Rb by germinated peanut seeds in the presence of DDT further supported the observations made with K(+). Cell number and length in plants were reduced in plants grown in DDT-treated soil and the role of calcium is discussed. It appears that growth inhibition in oil seed plants may arise from the low levels of Ca(2+) and K(+) in plants grown in DDT-treated soils.     

Effects of DDT on the growth of crop plants

The effects of DDT on the germination and growth of plants were studied using many crop species. Of the species tested, oil-rich seeds of plants, such as peanut (Arachis hypogaea) and mustard (Brassica juncea), were more prone to DDT induced inhibition of germination and subsequent plant growth than cereals, pulses and fibre crops, like rice (Oryza sativa), barley (Hordeum vulgare), mung bean Vigna radiata), pigeon pea (Cajanus cajan) and cotton (Gossypium hirsutum). Studies with (14)C labelled DDT showed that insecticide uptake by seeds was directly proportional to seed size. However, there was no direct relationship between DDT uptake by the seeds and its subsequent translocation to the growing regions or the degree of growth inhibition. Data suggest that oil content of the seeds per se has a bearing on the susceptibility or tolerance of a plant to DDT. It is suggested that lipids of the plant cell solubilize and disperse DDT in the cytoplasm, which, in turn, affects normal metabolism within the cell.     

Effects of different vermicompost extracts of palm oil mill effluent and palm-pressed fiber mixture on seed germination of mung bean and its relative toxicity

Several treatment technologies are available for the treatment of palm oil mill wastes. Vermicomposting is widely recognized as efficient, eco-friendly methods for converting organic waste materials to valuable products. This study evaluates the effect of different vermicompost extracts obtained from palm oil mill effluent (POME) and palm-pressed fiber (PPF) mixtures on the germination, growth, relative toxicity, and photosynthetic pigments of mung beans (Vigna radiata) plant. POME contains valuable nutrients and can be used as a liquid fertilizer for fertigation. Mung bean seeds were sown in petri dishes irrigated with different dilutions of vermicomposted POME-PPF extracts, namely 50, 60, and 70% at varying dilutions. Results showed that at lower dilutions, the vermicompost extracts showed favorable effects on seed germination, seedling growth, and total chlorophyll content in mung bean seedlings, but at higher dilutions, they showed inhibitory effects. The carotenoid contents also decreased with increased dilutions of POME-PPF. This study recommends that the extracts could serve as a good source of fertilizer for the germination and growth enhancement of mung bean seedlings at the recommended dilutions.     

陕北黄土区土壤石油污染物对玉米生长影响研究

为研究陕北黄土区土壤石油污染物对玉米种子出苗率和幼苗生长的影响,采用盆栽试验的方法,设置土壤不同石油浓度处理组,培养玉米2个月,测定了各处理组玉米的出苗率、株高、茎宽、生物量和叶片叶绿素浓度.结果表明:(1)土壤石油质量浓度即使为30 g/kg时,各处理组出苗率最终均为100％;土壤石油质量浓度达到20 g/kg及以上时,在一定程度上会推迟玉米种子的出苗时间.(2)土壤石油质量浓度达到1 g/kg就会对玉米茎的生长产生抑制作用,可以显著降低玉米株高,但对玉米茎宽影响不显著.随着土壤石油浓度的升高,对玉米株高的抑制作用显著增加.玉米茎宽总体上是随着土壤石油浓度的升高而减小,但土壤石油质量浓度为0～1g/kg或20～30 g/kg时,玉米茎宽没有显著差异.(3)当土壤石油质量浓度达到5 g/kg以上时,植株干质量随石油浓度升高而减少.土壤石油质量浓度达到20 g/kg时,会显著降低玉米根的含水率;达到30 g/kg时,会显著降低茎和叶的含水率.(4)土壤石油质量浓度为1、5 g/kg时,叶绿素a和叶绿素b浓度与土壤石油质量浓度为0 g/kg时没有显著差异;土壤石油质量浓度为10、20、30 g/kg时,叶绿素a和叶绿素b浓度显著低于土壤石油质量浓度为0 g/kg时,并且随土壤石油浓度的升高呈降低趋势.     

Phytotoxicity of nanoparticles: inhibition of seed germination and root growth

Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC50) of nano-Zn and nano-ZnO were estimated to be near 50mg/L for radish, and about 20mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles.     

Temporal ecological assessment of oil contaminated soils before and after bioremediation

Ecotoxicity methods were used to assess different soil and oil combinations before, during and after laboratory bioremediation with associated hydrocarbon analysis. Heavy, medium and light crude oil (API gravity 14, 30, and 55) was spiked (ca. 5% w/w) into two sandy soils in the laboratory having organic carbon concentrations of 0.3 (Norwood) and 4.7% (Norwood/Baccto). The earthworm (Eisenia fetida) 14-d lethality assay, the modified Microbics Microtox Solid-Phase assay, and the 14-d plant seed germination and growth assays using corn, wheat and oats, were spiked and tested during a 360-d laboratory remediation. Eisenia was the most sensitive of the three methods utilized with survival increasing throughout bioremediation with fastest toxicity reduction in the high carbon Norwood/Baccto soils where LC50's were 100% or greater at the end of 90-d whereas, > 150-d were required to achieve a similar result in the low carbon soil. Analysis of the undiluted treatments with oily soil alone showed that earthworm survival was high after 90-d in all high organic carbon soils, and after eight months in the low carbon soils, except for the Norwood soil-light oil treatment, which required 360-d to achieve 100% survival. The Microtox assay was less sensitive with EC50's 100% or greater observed after 90-d in high carbon soils and after 240-d for all low carbon soils. After bioremediation, no effects on seed germination were observed, although some plant growth inhibition effects remained. There was no direct correlation between total petroleum hydrocarbon concentrations and toxicity.     

Assessment of comparative toxicities of lead and copper using plant assay

The acute toxicities of lead (Pb) and copper (Cu) to important crop plants Sorghum bicolor, Cucumis sativus, Triticum aestivum, and Zea mays were compared. The EC50 values (the concentration of metals in the soil that reduces the growth of shoots and roots by 50%) were derived using the Trimmed Spearman-Karber method. The EC50s-shoot (root) in mg Pb kg-1 dry soil and mg Cu kg-1 dry soil were in the range of 519 to >1280 (285-445), and 48-232 (<40-110), respectively. Those concentrations are likely to occur in some abandoned mine areas in Korea. The figures indicate that Cu is more toxic than Pb to the plants in this study, and that root growth is more sensitive to the toxicity endpoint than shoot growth in Cu- or Pb-amended soils. On the other hand, seed germination is insensitive to both Pb and Cu toxicities. The Pb- and Cu-sensitive plants were also identified. Among the plants tested, T. aestivum and S. bicolor were most sensitive to Pb and Cu, respectively. Z. mays was most resistant to both Pb and Cu. The combined effects of Pb and Cu depend on the plant species, and no general phenomenon was observed. Bioaccumulations of Pb and Cu were observed in all test species, and they are concentration-dependent. These differences in the toxicities of Pb and Cu in plant species should be taken into account in biomonitoring and ecological risk assessment.     

Effects of distillery waste on the performance of Cicer arietinum L

The impact of distillery effluent in various concentrations (1, 2.5, 5, 10, 25, 50, 75 and 100%) on the seed germination, Speed of Germination Index, growth behaviour, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and the seed protein content of Cicer arietinum L. plants was investigated. The percentage and speed of germination of seeds were increasingly retarded with increase in effluent concentration and at 100% concentration there was no germination. The seedlings exhibited maximum shoot length at 5% concentration and maximum root length at 2.5% concentration. The values of root and shoot lengths, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and seed protein content in pot plants exhibited a gradual increase from the control up to 5% concentration and decreases at higher concentrations. The very high BOD load and the presence of excessive concentrations of soluble salts could be responsible for the toxicity of the effluent. The effluent at up to 5% concentration was, however, beneficial for the overall growth parameters studied and can thus be used as a liquid fertilizer.     

Effects of wastewater from olive processing on seed germination and early plant growth of different vegetable species

Abstract

The effects of wastewater from olive processing on seed germination and early plant growth of different vegetable species were examined. Three types of wastewater at different concentrations were tested: raw wastewater, wastewater with organic matter removed and deionized wastewater.

Results generally indicate an inhibitory effect on seed germination and early plant growth by all treatments containing any kind of wastewater. Of the three types of effluent, raw wastewater had the greatest depressive effect, followed by deionized wastewater and finally effluent with organic matter removed. Barley showed the least sensitivity to phytotoxic effects while tomato was the plant most affected. The remaining vegetable species showed an intermediate sensitivity.     

Soil ecotoxicity assessment using cadmium sensitive plants

Four crop plant species (sweet corn, Zea may; wheat, Triticum aestivum; cucumber, Cucumis sativus; and sorghum, Sorghum bicolor) were tested to assess an ecotoxicity in cadmium-amended soils. The measurement endpoints used were seed germination and seedling growth (shoot and root). The presence of cadmium decreased the seedling growth. The medium effective concentration values (EC50) for shoot or root growth were calculated by the Trimmed Spearman-Karber method. Due to the greater accumulation of Cd to the roots, root growth was a more sensitive endpoint than shoot growth. Bioavailability and transport of Cd within plant were related to concentration and species. The ratio of bioaccumulation factor (BAF) in the shoots to the roots indicated high immobilization of Cd in the roots. Seed germination was insensitive to Cd toxicity, and is not recommended for a suitable assay. Among the test plants and test endpoints, root growth of sorghum and cucumber appears to be a good protocol to assess ecotoxicity of soils contaminated by Cd.     

Degradation of atrazine, metolachlor, and pendimethalin in pesticide-contaminated soils: effects of aged residues on soil respiration and plant survival

This study was conducted to determine the effects of pesticide mixtures on degradation patterns of parent compounds as well as effects on soil microbial respiration. Bioavailability of residues to sensitive plant species was also determined. Soil for this study was obtained from a pesticide-contaminated area within an agrochemical dealer site. Degradation patterns were not affected by the presence or absence of other herbicides in this study. Atrazine concentrations were significantly lower at 21 through 160 days aging time compared to day 0 concentrations. Metolachlor and pendimethalin concentrations were not significantly different over time and remained high throughout the study. Microbial respiration was suppressed in treated soils from day 21 to day 160. Soybean and canola were the most successful plant species in the germination and survival tests. Generally, with increased aging of pesticides in soil, germination time decreased. Survival time of plants increased over time for some treatments indicating possible decreased bioavailability of pesticide residues. In some cases, survival time decreased at the longer 160-day aging period, possibly indicating a change in bioavailability, perhaps as the result of formation of more bioavailable and phytotoxic metabolites. No interactive effects were noted for mixtures of pesticides compared to individually applied pesticides in terms of degradation of the parent compound or on seed germination, plant survival, or microbial respiration.     

Degradation of atrazine,metolachlor, and pendimethalin in pesticide‐contaminated soils: Effects of aged residues on soil respiration and plant survival

Abstract

This study was conducted to determine the effects of pesticide mixtures on degradation patterns of parent compounds as well as effects on soil microbial respiration. Bioavailability of residues to sensitive plant species was also determined. Soil for this study was obtained from a pesticide‐contaminated area within an agrochemical dealer site. Degradation patterns were not affected by the presence or absence of other herbicides in this study. Atrazine concentrations were significantly lower at 21 through 160 days aging time compared to day 0 concentrations. Metolachlor and pendimethalin concentrations were not significantly different over time and remained high throughout the study. Microbial respiration was suppressed in treated soils from day 21 to day 160. Soybean and canola were the most successful plant species in the germination and survival tests. Generally, with increased aging of pesticides in soil, germination time decreased. Survival time of plants increased over time for some treatments indicating possible decreased bioavailability of pesticide residues. In some cases, survival time decreased at the longer 160‐day aging period, possibly indicating a change in bioavailability, perhaps as the result of formation of more bioavailable and phytotoxic metabolites. No interactive effects were noted for mixtures of pesticides compared to individually applied pesticides in terms of degradation of the parent compound or on seed germination, plant survival, or microbial respiration.     

Suitability of altai wildrye (Elymus angustus) and slender wheatgrass (Agropyron trachycaulum) for initial reclamation of saline composite tailings of oil sands

The reclamation of freshly produced composite or consolidated tailings (CT) is a challenge for the Oil Sands Industry in the boreal forest of Western Canada. CT tailings materials are characterized by a relatively high salinity (dominated by sodium, sulphate and chloride) and a high pH (8-9). A greenhouse study was conducted to determine the germination, survival, injury and early plant growth of two grass species recommended for land reclamation, altai wildrye (Elymus angustus Trin) and slender wheatgrass (Agropyron trachycaulum Link Malte), growing in two different oil sand CT tailings (alum-CT and gypsum-CT), with and without peat amendment. Ion accumulation in the resulting plant tissues was determined. Our results showed that slender wheatgrass was most affected by the tailings at the germination stage, while for altai wildrye, the early growth stage was the most sensitive stage. Alum-CT had similar or less negative impact on plants than gypsum-CT. Amendment of CT with peat limited the reduction in germination and growth that was recorded in plants growing directly in CT. Based on these results, recommendations were made to improve reclamation strategies.     

Phytotoxicity of composted herbal pharmaceutical industry wastes

This work demonstrates the phytotoxicity screening of composted herbal pharmaceutical industry waste (HPIW) using seed bioassay method. The composted industrial waste should be tested at lab scale prior to recommendation for land application. HPIW was mixed with soil to produce four treatments: T(1) (1:1), T(2) (1:2), T(3) (1:3), and T(4) (1:0) for toxicity screening using Pisum sativum seeds. After 72?h relative seed germination (RSG), relative root growth (RRG) and germination index (GI) were recorded. Seedlings were observed for further plant growth and tissue biochemistry (chlorophyll, soluble sugar, starch, carotenoid, and protein) estimation. RSG, RRG, and GI values were better in T(1) and T(2) than others. GI was in the ranges of 36.62?% (T(4)) to 170.38?% (T(2)). The seedling growth and biochemical parameters were better in seedling obtained from potting media containing low proportion of HPIW (i.e., T(1) and T(2)). Results clearly suggested that composted HPIW may be utilized effectively for crop production after dilution under sustainable farming system program.     

Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities.     

Effects of VOCs on herbaceous plants in an open-top chamber experiment

A selection of herbaceous plants representing the ground flora around a typical chemical installation in the UK was exposed continuously for 7 weeks to a mixture of six VOCs (acetone, acetonitrile, dichloromethane, ethanol, methyl t-butyl ether and toluene) in open-top chambers. Exposure concentrations were based on predictions of atmospheric dispersion from a single source, at a distance of approximately 2 km. The effects of continuous exposure, representing a worst-case, were measured in terms of uncontrolled water loss from leaves, leaf wettability, chlorophyll content and fluorescence, dry matter production and detailed observations of changes in plant growth and phenology. There were significant effects of VOC exposure on seed production, leaf water content and photosynthetic efficiency in some plant species. Such effects may be detectable in vegetation close to major industrial point sources of VOCs, or as a result of an accidental release of material during manufacture or transport. Some of the species tested e.g. birdsfoot trefoil (Lotus corniculatus L.) seem to be promising as potential bioindicators for VOCs, but there may be other even more sensitive species waiting to be discovered. However, the most obvious and conveniently measured response to VOCexposure in the birdsfoot trefoil (premature senescence i.e. advanced timing of seed pod production) could easily be confused in the field with climatic influences. It is also uncertain at this stage whether any of the effects observed would lead to longer term ecological changes in natural plant communities, through biased competition between sensitive and more tolerant species.