RESUMEN
Paspalum distichum L. was tested to evaluate its ability to phytoremediate mercury (Hg) contaminated soil over a 60-d period by analysis of the total Hg concentrations in roots and leaves. Hg concentration in Hg-contamination soil decreased by 70.0⯵gâ¯g-1 after 60 day of grass cultivation and Hg was readily taken up by the roots (4.51⯱â¯1.90⯵gâ¯g-1) rather than the leaves (0.35⯱â¯0.02⯵gâ¯g-1). In addition, a comparative proteomic study was performed to unravel the protein expression involved in the Hg stress response in P. distichum L. A total of 49 proteins were classified as differentially proteins in the roots by the 'top three' proteomic analysis, of which 32 were up-regulated and 17 down-regulated in response to Hg stress. These changed proteins were classified by gene ontology analysis into five complex molecular functions involving photosynthesis and energy metabolism (31%), oxidative stress (14%), protein folding (16%), sulfur compound metabolism (10%), metal binding, and ion transport (29%). Moreover, the protein expression patterns were consistent with the metabolism pathway results. Overall, the results contribute to our understanding of the molecular mechanisms of the Hg response in P. distichum and we propose a theoretical basis for the phytoremediation of Hg-contaminated soils.
Asunto(s)
Mercurio/toxicidad , Estrés Oxidativo/efectos de los fármacos , Paspalum/efectos de los fármacos , Proteínas de Plantas/metabolismo , Contaminantes del Suelo/toxicidad , Biodegradación Ambiental , Regulación hacia Abajo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Mercurio/metabolismo , Estrés Oxidativo/genética , Paspalum/genética , Paspalum/metabolismo , Fotosíntesis/efectos de los fármacos , Fotosíntesis/genética , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Proteómica , Contaminantes del Suelo/metabolismo , Regulación hacia ArribaRESUMEN
Metal load is an abiotic stress that becomes stronger by continual industrial production, wastage, and long-range transport of contaminants. It deteriorates the conditions of agricultural soil that leads to lower growth of cereals as well as decreasing nutritional value of harvested grains. Cadmium (Cd) entry by food chain also affects the health of population. The present study is focused on finding out the superior cereal variety under increasing Cd regime. The plants were grown in increasing Cd levels (0-1000 µM) in the medium and were investigated on 15th day of the exposure. Various parameters like antioxidative enzymes and osmoprotectant levels were studied in both roots and shoots. Cd accumulation in plant organs was determined by atomic absorption spectrophotometry (AAS). Analysis of stress tolerance mechanisms through reactive oxygen species (ROS) scavenging and better partitioning of Cd in roots indicated kodo millet to be more stress tolerant than wheat.
Asunto(s)
Cadmio/toxicidad , Paspalum/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Triticum/efectos de los fármacos , Biodegradación Ambiental , Paspalum/genética , Paspalum/crecimiento & desarrollo , Especificidad de la Especie , Estrés Fisiológico , Triticum/genética , Triticum/crecimiento & desarrolloRESUMEN
Forage species common to the southern USA Piedmont region, Lolium arundinacea, Paspalum dilatatum, Cynodon dactylon and Trifolium repens, were established in a model pasture system to test the future climate change scenario of increasing ozone exposure in combination with varying rainfall amounts on community structure and nutritive quality. Forages were exposed to two levels of ozone [ambient (non-filtered; NF) and twice ambient (2×) concentrations] with three levels of precipitation (average or ±20% of average) in modified open-top chambers (OTCs) from June to September 2009. Dry matter (DM) yield did not differ over the growing season between forage types, except in primary growth grasses where DM yield was higher in 2× than NF treatment. Primary growth clover decreased in nutritive quality in 2× ozone because of increased concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). Re-growth clover exhibited the largest decrease in nutritive quality, whereas grasses were not adversely affected in 2× ozone. Re-growth grasses responded positively to 2× ozone exposure, as indicated in increased relative food value (RFV) and percentage crude protein (CP) than NF-exposed re-growth grasses. Effects of precipitation were not significant over the growing season for primary or re-growth forage, except in primary growth grasses where DM yield was higher in chambers with above average (+20%) precipitation. Total canopy cover was significantly higher over the growing season in chambers receiving above average precipitation, but no significant effects were observed with ozone. Results indicate shifts in plant community structure and functioning related to mammalian herbivore herbivory in future climate change scenarios.
Asunto(s)
Cynodon/efectos de los fármacos , Lolium/efectos de los fármacos , Ozono/efectos adversos , Paspalum/efectos de los fármacos , Trifolium/efectos de los fármacos , Animales , Biomasa , Clima , Cambio Climático , Cynodon/fisiología , Pradera , Lolium/fisiología , Valor Nutritivo , Paspalum/fisiología , Lluvia , Estaciones del Año , Trifolium/fisiologíaRESUMEN
We aimed to verify whether morphoanatomic alterations occur in response to excess iron, in roots of Setaria parviflora and Paspallum urvillei (Poaceae), and to localize the presence of the sites of iron accumulation. Plants were subjected to 0.009, 1, 2, 4, and 7 mM Fe-EDTA in nutrient solution. Both species presented iron contents in the roots above the critical toxicity level. The presence of iron plaque on roots of the two species was confirmed, and it may have reduced iron absorption by the plants. Roots from the two species showed typical visual symptoms of stress by excess iron: change in color and mucilaginous and flaccid appearance. Anatomical damage was observed in both species: aerenchyma disruption, alterations in endodermal cells, and irregular shape of both vessel and sieve tube elements. The metal was histolocalized in the cortex and in protoxylem and metaxylem cell walls in both species, which suggests a detoxification strategy for the excess iron. Phenolic compounds were not histolocalized in roots. Microscopic analyses were therefore effective in evaluating the real damage caused by excess iron.
Asunto(s)
Hierro/toxicidad , Paspalum/efectos de los fármacos , Raíces de Plantas/efectos de los fármacos , Setaria (Planta)/efectos de los fármacos , Pared Celular/metabolismo , Hierro/metabolismo , Metales , Microscopía Electrónica de Rastreo , Paspalum/metabolismo , Paspalum/ultraestructura , Raíces de Plantas/metabolismo , Raíces de Plantas/ultraestructura , Plantas , Poaceae , Setaria (Planta)/metabolismo , Setaria (Planta)/ultraestructuraRESUMEN
This study aimed to assess the influence of excess iron on the capacity of accumulation of this heavy metal, mineral composition, and growth of Setaria parviflora and Paspalum urvillei. Seedlings were submitted to 0.009; 1; 2; 4; and 7 mM of Fe-EDTA. In both species there was an increase in the concentration of Fe, Zn, P, and Ca and a decrease in Mn, K, and Mg in the iron plaque. Both species accumulated more iron in roots. In the shoots, S. parviflora showed higher iron content, except at 7 mM. Iron altered the contents of Fe, Cu, K, and Mg in roots, and of Fe, Mn, Zn, N, P, K, Ca, and Mg in shoots. The two species tolerated high iron concentrations and accumulated high content of this element in both shoots and roots. The iron did not reduce their growth. Both species are indicated for studies aiming restoration of iron-contaminated areas.
Asunto(s)
Hierro/toxicidad , Paspalum/efectos de los fármacos , Setaria (Planta)/efectos de los fármacos , Tolerancia a Medicamentos , Hierro/metabolismo , Metales/metabolismo , Nitrógeno/metabolismo , Paspalum/crecimiento & desarrollo , Paspalum/metabolismo , Fósforo/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/crecimiento & desarrollo , Brotes de la Planta/metabolismo , Plantones/efectos de los fármacos , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Setaria (Planta)/crecimiento & desarrollo , Setaria (Planta)/metabolismoRESUMEN
Setaria parviflora (Poir.) Kerguélen and Paspalum urvillei Steudel are grasses that grow naturally in a soil with high iron contents. This study aimed to characterize morphoanatomically and histochemically the iron phytotoxicity on leaves and evaluate the phytoextraction potential of these grasses. Saplings were cultivated in hydroponic solution with and without excess Fe-EDTA. Regarding measurements taken on leaves, reduction was observed among treatments of Fe-EDTA on height values of abaxial epidermis and bundle sheath in both species. As for iron histolocalization, stronger reaction was observed in leaves of S. parviflora, in comparison with P. urvillei. Anatomical damage, such as protoplast retraction, irregular xylem, changes in cell volume, and cell collapse, and visual symptoms, like leaf bronzing, chlorosis, and necrosis, were similar in both species when exposed to excess iron; however, P. urvillei showed more severe damage. This species accumulated more iron in shoots than S. parviflora and therefore is more favorable for use in phytoextraction. The root system of both species accumulated higher iron concentrations in relation to shoots.
Asunto(s)
Hierro/toxicidad , Paspalum/efectos de los fármacos , Setaria (Planta)/efectos de los fármacos , Biodegradación Ambiental , Hierro/metabolismo , Paspalum/anatomía & histología , Paspalum/metabolismo , Hojas de la Planta/anatomía & histología , Hojas de la Planta/metabolismo , Raíces de Plantas/metabolismo , Brotes de la Planta/metabolismo , Setaria (Planta)/anatomía & histología , Setaria (Planta)/metabolismoRESUMEN
BACKGROUND: Pesticides are developed with carriers to improve their physicochemical properties and, accordingly, the bioefficacy of the applied formulation. For foliar-applied herbicide, generally less than 0.1% of the active ingredient reaching the target site could reduce pesticide performance. Recently, a carrier of nanoemulsion consisting of oil, surfactant and water, with a particle size of less than 200 nm, has been shown to enhance drug permeability for skin penetration in pharmaceutical delivery systems. In the present work, the aim was to formulate a water-soluble herbicide, glyphosate isopropylamine (IPA), using a green nanoemulsion system for a biological activity study against the weeds creeping foxglove, slender button weed and buffalo grass. RESULTS: The nanoemulsion formulations displayed a significantly lower spray deposition on creeping foxglove (2.9-3.5 ng cm(-2) ), slender button weed (2.6-2.9 ng cm(-2) ) and buffalo grass (1.8-2.4 ng cm(-2) ) than Roundup(®) (3.7-5.1 ng cm(-2) ). The visible injury rates of weeds treated with the nanoemulsion formulations were statistically equivalent to those relating to Roundup(®) at 14 days after treatment, with a control range of 86.67-96.67%. CONCLUSION: It was hypothesised that the significant difference in spray deposition with equal injury rates can be attributed to enhanced bioactivity of the nanoemulsion formulations. This initial discovery could be the platform for developing better penetration of agrochemical formulations in the future.
Asunto(s)
Acanthaceae/efectos de los fármacos , Glicina/análogos & derivados , Herbicidas/farmacología , Paspalum/efectos de los fármacos , Rubiaceae/efectos de los fármacos , Control de Malezas/métodos , Acanthaceae/crecimiento & desarrollo , Glicina/análisis , Glicina/química , Glicina/farmacología , Herbicidas/análisis , Herbicidas/química , Malasia , Nanopartículas/química , Paspalum/crecimiento & desarrollo , Propilaminas/análisis , Propilaminas/química , Rubiaceae/crecimiento & desarrollo , GlifosatoRESUMEN
Triclosan (TCS) is an antimicrobial compound commonly found in biosolids. Thus, plants grown in biosolids-amended soil may be exposed to TCS. We evaluated the plant toxicity and accumulation potential of biosolids-borne TCS in two vegetables (lettuce and radish) and a pasture grass (bahia grass). Vegetables were grown in growth chambers and grass in a greenhouse. Biosolids-amended soil had TCS concentrations of 0.99, 5.9, and 11 mg/kg amended soil. These TCS concentrations represent typical biosolids containing concentrations of 16 mg TCS/kg applied at agronomic rates for 6 to 70 consecutive years, assuming no TCS loss. Plant yields (dry wt) were not reduced at any TCS concentration and the no observed effect concentration was 11 mg TCS/kg soil for all plants. Significantly greater TCS accumulated in the below-ground biomass than in the above-ground biomass. The average bioaccumulation factors (BAFs) were 0.43 ± 0.38 in radish root, 0.04 ± 0.04 in lettuce leaves, 0.004 ± 0.002 in radish leaves, and <0.001 in bahia grass. Soybean (grain) and corn (leaves) grown in our previous field study where soil TCS concentrations were lower (0.04-0.1 mg/kg) had BAF values of 0.06 to 0.16. Based on the data, we suggest a conservative first approximate BAF value of 0.4 for risk assessment in plants.
Asunto(s)
Antiinfecciosos/toxicidad , Lactuca/efectos de los fármacos , Paspalum/efectos de los fármacos , Raphanus/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Triclosán/toxicidad , Antiinfecciosos/metabolismo , Biomasa , Productos Agrícolas , Grano Comestible/metabolismo , Lactuca/crecimiento & desarrollo , Lactuca/metabolismo , Paspalum/crecimiento & desarrollo , Paspalum/metabolismo , Hojas de la Planta/metabolismo , Raphanus/crecimiento & desarrollo , Raphanus/metabolismo , Suelo , Contaminantes del Suelo/metabolismo , Glycine max/metabolismo , Triclosán/metabolismo , Zea mays/metabolismoRESUMEN
BACKGROUND: Bahiagrass (Paspalum notatum Flueggé) is a poor host of several soilborne pests of vegetable crops; therefore vegetable crops are commonly grown in a rotation with bahiagrass pastures in Florida. The herbicide aminopyralid provides foliar and soil residual weed control and increases forage production in bahiagrass pastures; however, the soil residual activity of aminopyralid makes carryover injury likely in subsequent sensitive vegetable crops. Field research was conducted to determine the sensitivity of five vegetable crops to soil residues of aminopyralid. RESULTS: At an aminopyralid soil concentration of 0.2 µg kg(-1) (the limit of quantitation for aminopyralid in this research), crop injury ratings were 48% (bell pepper), 67% (eggplant), 71% (tomato), 3% (muskmelon) and 3% (watermelon), and fruit yield losses (relative to the untreated control) at that concentration were 61, 64, 95, 8 and 14% in those respective crops. CONCLUSIONS: The crops included in this research were negatively affected by aminopyralid at soil concentrations less than the limit of quantitation (0.2 µg kg(-1) ). Therefore, it was concluded that a field bioassay must be used to determine whether carryover injury will occur when these crops are planted on a site where aminopyralid has been previously applied.
Asunto(s)
Herbicidas/farmacología , Residuos de Plaguicidas/farmacología , Suelo/análisis , Verduras/efectos de los fármacos , Verduras/crecimiento & desarrollo , Agricultura , Florida , Herbicidas/análisis , Paspalum/efectos de los fármacos , Paspalum/crecimiento & desarrollo , Residuos de Plaguicidas/análisisRESUMEN
Triclocarban (TCC) toxicity and bioaccumulation data are primarily limited to direct human and animal dermal exposures, animal ingestion exposures to neat and feed-spiked TCC, and/or aquatic organism exposures. Three non-human, terrestrial organism groups anticipated to be the most highly exposed to land-applied, biosolids-borne TCC are soil microbes, earthworms, and plants. The three ecological receptors are expected to be at particular risk due to unique modes of exposure (e.g. constant, direct contact with soil; uptake of amended soil and pore water), inherently greater sensitivity to environmental contaminants (e.g. increased body burdens, permeable membranes), and susceptibility to minute changes in the soil environment. The toxicities of biosolids-borne TCC to Eisenia fetida earthworms and soil microbial communities were characterized using adaptations of the USEPA Office of Prevention, Pesticides, and Toxic Substances (OPPTS) Guidelines 850.6200 (Earthworm Subchronic Toxicity Test) and 850.5100 (Soil Microbial Community Toxicity Test), respectively. The resultant calculated TCC LC50 value for E. fetida was 40 mg TCC kg amended fine sand(-1). Biosolids-borne TCC in an amended fine sand had no significant effect on soil microbial community respiration, ammonification, or nitrification. Bioaccumulation of biosolids-borne TCC by E. fetida and Paspulum notatum was measured to characterize potential biosolids-borne TCC movement through the food chain. Dry-weight TCC bioaccumulation factor (BAF) values in E. fetida and P. notatum ranged from 5.2-18 and 0.00041-0.007 (gsoil gtissue(-1)), respectively.
Asunto(s)
Antiinfecciosos Locales/toxicidad , Carbanilidas/toxicidad , Contaminantes del Suelo/toxicidad , Amoníaco/análisis , Animales , Antiinfecciosos Locales/metabolismo , Carbanilidas/metabolismo , Nitrificación/efectos de los fármacos , Oligoquetos/efectos de los fármacos , Oligoquetos/metabolismo , Paspalum/efectos de los fármacos , Paspalum/metabolismo , Suelo/química , Microbiología del Suelo , Contaminantes del Suelo/metabolismoRESUMEN
This study assessed the heavy metal (Cr, Mn, Ni, Cu, Zn, and Pb) uptake and its effect on biochemical parameters in Paspalum distichum, a wetland plant. Sludge collected from Bhalswa waste dump, New Delhi, was used as heavy metal source and dosed in different proportions viz. 20%, 40%, 60%, and 80% to the garden soil. The plants accumulated metals mostly in belowground organs. The metal accumulation followed the order: Cr>Mn>Cu>Zn>Ni>Pb. The range of heavy metal concentration in tissue of belowground organs after 180 days of growth was 1,778.65-4,288.01 ppm Cr, 828.11-1,360 ppm Mn, 236.52-330.07 ppm Ni, 155.79-282.35 ppm Cu, 27.05-91.16 ppm Zn, and 27.09-50.87 ppm Pb. The biochemical parameters viz. chlorophyll and protein contents and peroxidase (POD) activity exhibited no considerable adverse effect indicating the plants' tolerance towards heavy metals. The high POD activity and synthesis of new protein bands at high sludge-dosed plants were also in support of this fact.
Asunto(s)
Metales Pesados/metabolismo , Paspalum/metabolismo , Contaminantes del Suelo/metabolismo , Clorofila/metabolismo , Metales Pesados/toxicidad , Nitrógeno/metabolismo , Paspalum/efectos de los fármacos , Paspalum/crecimiento & desarrollo , Peroxidasa/metabolismo , Fósforo/metabolismo , Proteínas de Plantas/metabolismo , Potasio/metabolismo , Contaminantes del Suelo/toxicidad , HumedalesRESUMEN
Paspalum notatum Flugge has been widely utilized for the purpose of ecological restoration of degraded land in the tropics and subtropics, where soil active aluminium (Al) is usually high as a result of acidification. Pot experiments were conducted to determine Al toxicity on P. notatum and to compare its potential to remove Al with another three plant species, Vetiveria zizanioides, Tristania conferta and Schima wallichii. In the Al addition experiment, the biomass of P. notatum and Al accumulation significantly decreased as the added Al concentration increased, but Al concentration in the plant markedly increased. A parallel experiment was conducted with the above four species, grown in lateritic soil and in oil shale waste containing high concentration of active Al. The biomasses of all four species were reduced obviously in the waste compared to in the soil. The effects of substrate on Al concentration, accumulation and translocation efficiency differed among species, and plants had significantly higher Al accumulation factors when grown in the soil than in the waste. Most of the Al taken up by P. notatum was transferred to above-ground parts; as a result, Al concentration in stems and leaves became quite high, over 1000 or even 3000 mg kg(-1); whereas for the other three species, Al concentration in shoots was much lower than in roots. Paspalum notatum was therefore much higher than the other three species with regard to Al translocation efficiency and therefore P. notatum may be regarded as both an effective Al hyper-accumulator and a potential Al hyper-remover.
Asunto(s)
Aluminio/metabolismo , Aluminio/toxicidad , Paspalum/efectos de los fármacos , Paspalum/metabolismo , Contaminantes del Suelo/metabolismo , Contaminantes del Suelo/toxicidad , Biodegradación Ambiental , Biomasa , China , Chrysopogon/efectos de los fármacos , Chrysopogon/metabolismo , Ciudades , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Tallos de la Planta/efectos de los fármacos , Tallos de la Planta/metabolismoRESUMEN
Pot experiments were conducted to examine the toxic effects of chlorate on bermudagrass, bahiagrass, and longan seedling with a focus on arbuscular mycorrhizal fungi-plant associations. The results show that application of chlorate could cause slight soil acidification, but the resulting pH was still around 5.5, which is unlikely to adversely affect plant growth. Increase in the application rate of chlorate resulted in a decrease in colonization rate of arbuscular mycorrhizal fungi in plant roots, P uptake by the plants and plant biomass. This appears to suggest that the reduction in plant growth may be related to impeded uptake of P by the plants due to the failure of the plants to form sufficient mycorrhizal associations when chlorate is in sufficient amounts to cause toxicity to arbuscular mycorrhizal fungi. Under the experimental conditions set for this study, bermudagrass suffered from stronger chlorate stress than bahiagrass and longan seedling did in terms of plant-arbuscular mycorrhizal fungi (AMF) symbiosis development.
Asunto(s)
Cloratos/toxicidad , Hongos/efectos de los fármacos , Micorrizas/efectos de los fármacos , Plantas/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Biomasa , Cloratos/metabolismo , Cynodon/efectos de los fármacos , Cynodon/crecimiento & desarrollo , Cynodon/microbiología , Hongos/crecimiento & desarrollo , Herbicidas/metabolismo , Herbicidas/toxicidad , Concentración de Iones de Hidrógeno , Micorrizas/crecimiento & desarrollo , Micorrizas/metabolismo , Paspalum/efectos de los fármacos , Paspalum/crecimiento & desarrollo , Paspalum/microbiología , Desarrollo de la Planta , Plantas/microbiología , Plantones/crecimiento & desarrollo , Plantones/microbiología , Suelo/química , Microbiología del Suelo , Contaminantes del Suelo/metabolismo , SimbiosisRESUMEN
BACKGROUND, AIMS AND SCOPE: The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. METHODS: The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg(-1) (37.5 kg ha(-1)) and 150 mg kg(-1) (75 kg ha(-1)) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid out following a 3 x 2 factorial experiment in a completely randomized design. RESULTS: On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85-39.39 Mg ha(-1)). Carabaograss had the lowest herbage mass production of 4.12 Mg ha(-1) and 5.72 Mg ha(-1) from soils added with 75 and 150 mg Pb kg(-1), respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 +/- 2.81 mg kg(-1)). This was followed by cogongrass (2.34 +/- 0.52 mg kg(-1)) and carabaograss with a mean Pb level of 0.49 +/- 0.56 mg kg(-1). Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg kg(-1)) to the soil. DISCUSSION: Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency of plants as phytoremediators could be correlated with the plants' total biomass. This implies that the higher the biomass, the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most metal removal from the soil. CONCLUSIONS: The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals, particularly Pb. RECOMMENDATIONS AND PERSPECTIVES: High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters, battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and public parks.
Asunto(s)
Plomo/metabolismo , Poaceae/metabolismo , Contaminantes del Suelo/metabolismo , Biodegradación Ambiental , Chrysopogon/efectos de los fármacos , Chrysopogon/metabolismo , Chrysopogon/fisiología , Plomo/farmacología , Paspalum/efectos de los fármacos , Paspalum/metabolismo , Paspalum/fisiología , Filipinas , Poaceae/efectos de los fármacos , Poaceae/fisiología , Contaminantes del Suelo/farmacologíaRESUMEN
Culture conditions have been established for the induction of callus from different explants of Paspalum simplex. Fast-growing calli were obtained from hypocotyls and roots excised from 5-day-old seedlings on culture medium containing 2,4-dichlorophenoxyacetic acid and kinetin. Rapid plant regeneration from both apomictic and sexual lines was achieved when the medium was supplemented with alpha-naphthaleneacetic acid and benzylaminopurine. Restriction fragment length polymorphism analysis of the apomixis-controlling region of the regenerated plants showed an absence of restriction site variation for the loci analysed, whereas various degrees of variation were detected for the DNA methylation sites of the same loci.
Asunto(s)
Paspalum/genética , Paspalum/fisiología , Polimorfismo de Longitud del Fragmento de Restricción , Regeneración/fisiología , Adenina/análogos & derivados , Adenina/farmacología , Medios de Cultivo/química , Técnicas de Cultivo , Metilación de ADN , Variación Genética , Ácidos Naftalenoacéticos/farmacología , Paspalum/efectos de los fármacos , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/fisiología , Polimorfismo Genético , Regeneración/efectos de los fármacos , Mapeo RestrictivoRESUMEN
To assess the impact of S fertilization on bahiagrass (Paspalum notatum) quality and Cu metabolism in cattle, two studies were conducted during the summer grazing season (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) received the same fertilizer treatment in each growing season, consisting of 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Forage sampling was conducted at 28-d intervals following fertilization by the collection of whole plants (four samples/pasture) in randomly distributed 1-m2 grazing exclusion cages and analyzed for CP, in vitro organic matter digestibility, S, P, Ca, K, Mg, Na, Fe, Al, Mn, Cu, and Zn. To determine the effect of fertilizer treatment on liver trace mineral concentrations in grazing cattle, random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period in 2000. Ammonium sulfate fertilization increased (P < 0.001) forage S concentration in both years. Plant tissue N concentrations were increased by N fertilization, regardless of source, in 2000, but not in 1999. Cows grazing AS pastures had lower (P < 0.05) liver Cu concentrations at the end of the study period in 2000 compared to AN and C. In Exp. 2, 37 Cu-deficient heifers grazing AS fertilized pastures were obtained from the same location and allocated to one of two treatments, consisting of supplements providing 123 mg/d of either inorganic (Cu sulfate; n = 12) or organic (Availa-Cu; n = 15) Cu. Treatments were delivered for 83 d. Liver Cu increased over time in all heifers regardless of treatment; however, heifers supplemented with Availa-Cu tended (P = 0.09) to have higher mean liver Cu concentrations than those receiving Cu sulfate. The results of these studies indicate that AS fertilization of bahiagrass increases forage S concentrations. When provided free-choice access to a complete salt-based trace mineral supplement, cows grazing AS-fertilized pastures had lower liver Cu concentrations than cows grazing pastures fertilized with AN; upon removal from high-S pastures, cattle were able to respond to Cu supplementation.