Accumulation In Plants Research Articles

Effects of Pb in Tagetes minuta L. (Asteraceae) leaves and its relationship with volatile compounds

Soil has traditionally been the disposal site for most heavy metal waste. Since metals can not be degraded, soil remediation requires their removal with phytoextraction, being a cost effective alternative in which metal accumulator plants are used to remove toxic metals from soil. Aromatic crops, used for the production of essential oils, may be a suitable alternative to be used in agricultural soils contaminated with heavy metals, since after removal, a marketable product is left. The present study investigated the effects that high concentrations of lead (Pb) have on the volatile compounds in leaves of Tagetes minuta L., growing near a battery recycling plant and also determined whether Pb was present in its essential oil. In this way, it could be evaluated whether the use of this species for Pb phytoremediation supports safe production. To carry this out, it was determined whether the essential oil obtained by hydrodistillation contained Pb, which was also checked for each individual of T. minuta, by measuring the amount of this metal in leaves using the technique of X-ray fluorescence and calculating the percentages of volatiles by the HS-SPME technique.The essential oils extracted by hydrodistillation did not have any detectable Pb, there by demonstrating that it is not transferred to the essential oil. Regarding the volatiles, the highest concentrations encountered were for cis-tagetone, dihydrotagetone and verberone. Furthermore, the compounds β-ocimene and α-thujone correlated significantly with the Pb concentration in leaves, indicating that the increase of Pb in T. minuta may favor synthesis of these compounds. In conclusion, T. minuta is a resistant plant that can grow in Pb polluted soils and accumulate the contaminant in aerial tissues, while providing an economic return through the production of essential oil free of Pb.

Response of different wheat genotypes to different sowing time in relation to GDD accumulation

An experiment on response of different wheat genotype to different sowing time in relation to GDD accumulation was carried out in Rabi season of 2010-11 at the research field of Wheat Research Unit, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (M.S.). The treatments consisted of two sowing dates 45 MW, 48 MW and twenty wheat genotypes AKDW-4021, AKDW-2997-16, AKDW-4749,AKDW-4750, AKDW-4132-2, AKDW-3931-2, HD2189, HIDW-295, NIAW-34, AKAW-4627, LOK-1, MACS -1967, AKAW-3997, AKAW-4073, AKAW-4210-6, AKAW-4493, AKAW-4705, AKAW–4731, AKAW–4636 and AKAW-4739. The experiment was laid out in a Factorial Randomized Blocked Design with three replications. The soil was clayey with pH 7.89 containing N-206.00, P-15.86 and K303.43 kg ha value after harvest. The growth, yield attributes and yield observations showed significant increase when wheat crop was sown at 45 MW than 48 MW. Grain yield obtained was significantly higher at 45 MW sowing. Wheat crop sown at 48 MW required significantly lower cumulative growing degree days (GDD) and helio thermal units for completion of reproductive phase than 45 MW sown crop. Correlation studies reveal that correlation between straw yield and bright sunshine hours found to be significant showing the negative correlation and correlation between straw yield and relative humidity was observed to be significant showing the positive correlation. Sowing of wheat crop at 45meteorological week was recorded most economical under different date of sowing condition.Out of genotypes, AKAW4647 was superior over others in respect of tillers m, chlorophyll content plant, dry matter accumulation plant, number of grains earhead, yield per day per plant (g), rate of grain filling, grain yield (q ha), straw yield (q ha ) and test weight.

Silicon enhanced salt tolerance by improving the root water uptake and decreasing the ion toxicity in cucumber.

Although the effects of silicon application on enhancing plant salt tolerance have been widely investigated, the underlying mechanism has remained unclear. In this study, seedlings of cucumber, a medium silicon accumulator plant, grown in 0.83 mM silicon solution for 2 weeks were exposed to 65 mM NaCl solution for another 1 week. The dry weight and shoot/root ratio were reduced by salt stress, but silicon application significantly alleviated these decreases. The chlorophyll concentration, net photosynthetic rate, transpiration rate and leaf water content were higher in plants treated with silicon than in untreated plants under salt stress conditions. Further investigation showed that salt stress decreased root hydraulic conductance (Lp), but that silicon application moderated this salt-induced decrease in Lp. The higher Lp in silicon-treated plants may account for the superior plant water balance. Moreover, silicon application significantly decreased Na+ concentration in the leaves while increasing K+ concentration. Simultaneously, both free and conjugated types of polyamines were maintained at high levels in silicon-treated plants, suggesting that polyamines may be involved in the ion toxicity. Our results indicate that silicon enhances the salt tolerance of cucumber through improving plant water balance by increasing the Lp and reducing Na+ content by increasing polyamine accumulation.

Screening for new accumulator plants in potential hazards elements polluted soil surrounding Peruvian mine tailings

Tailings usually provide an unfavorable substrate for plant growth because of their multi-stress environment. Plants growing on naturally metal-enriched soils are of particular interest in this perspective, since they are genetically tolerant to high metal concentrations and have an excellent adaptation to extreme conditions. Soil and plant samples were taken in Peru, at a polymetallic mine (mainly Ag, Pb and Cu) in Cajamarca Province, Hualgayoc district. Top soils (0–20cm) were analyzed for physical and chemical properties by standard methods. Total As, Cu, Pb and Zn concentrations in top soils were determined by ICP–OES. Similar metals in plants were analyzed separately (aerial and root system) by ICP–MS. Translocation Factor (TF) and Shoot Accumulation Factor (SAF) were determined to assess the tolerance strategies developed by these species and to evaluate their potential for phytoremediation purposes. The non-polluted soils had near neutral pH (6.8±0.1), a great content of organic carbon (42±4.0gkg−1) and a silt loamy texture. Soil and plant samples were taken at four locations (CA1, CA2, CA3, CA4) as well as the local reference topsoil (CA0). The range of total soil values in mg kg−1 is as follows: As 280–1029; Cu 256–2070; Pb 3992–16,060 and Zn 11,550–28,059, respectively. Unusual elevated concentrations of Pb (over 1000mgkg−1) and TF greater than one were detected in shoots of six different plants species (Ageratina sp., Achyrocline alata (Kunth) DC., Cortaderia hapalotricha Pilg., Epilobium denticulatum Ruiz & Pav., Taraxacum officinale Weber and Trifolium repens Walter). Ageratina sp and E. denticulatum also showed elevated concentrations of Zn (over 10,000mgkg−1) and TF greater than one in some studied locations. However, the SAF was smaller than one. Controlled-environment studies must be performed to definitively confirm the Pb hyperaccumulation character of the cited plant species.

Plants to harvest rhenium: scientific and economic viability

Rhenium (Re) is one of the rarest (7 × 10−8 %) and most widely dispersed elements on Earth’s upper crust. As a consequence of its scarcity, Re is also one of the most expensive metals in the world market. Re is indeed highly demanded by the aerospace industry for the production of high-temperature superalloy turbine blades. There is a lack of study on the viability of Re phytomining. The occurrence of Re in vegetation surrounding natural and anthropogenic sources of Re suggests the ability of plants for Re accumulation and biogeochemical indication. Here we studied the aptitude of Indian mustard and scouring rush to uptake Re, in order to test the feasibility of Re phytomining. An organic substrate was spiked with KReO4 to attain Re concentrations of 5, 10, 20, 40, and 80 mg kg−1. The plants were grown for 45 and 75 days under controlled greenhouse conditions. Plant tissue samples from roots and shoots were collected in septuplicate at both harvests and analysed by atomic emission spectroscopy. Our results show high concentrations of Re in plants, ranging from 1553 to 22,617 mg kg−1 at 45 days and from 1348 to 23,396 mg kg−1 at 75 days for Indian mustard range. A profit of 3906 US$ ha−1 harvest−1 is expected from the recovered Re. Our findings thus demonstrate for the first time the scientific and economic viability of Re phytomining.

(Invited) Green Synthesis of Porous Silicon Derived from Accumulator Plants: Associated Morphologies and Stabilization of a Natural Bioactive Extract

Elemental silicon, in nanostructured mesoporous form, is attracting extensive attention in biomedically-relevant applications such as biosensing, drug delivery, and tissue engineering. The use of electronic grade silicon as a feedstock material for production of this material has economic obstacles to high volume applications. Alternatives, such as open circuit stain etching processes in conjunction with lower cost metallurgical grade Si, for example, are appealing, yet face common issues like high volume use of hydrofluoric acid and other challenges such as generation of uniform high porosity frameworks. In contrast to the above, a more eco-friendly option is the use of established silicon accumulator plants as sustainable starting materials for high surface area porous silicon structures. We have recently reported1 a facile route that employs well-known plants such as horsetail (equisetum arvense, equisetum telmatia) and bamboo (bambuseae, tabasheer) as feedstocks. This process first entails the calcination of a given plant material to porous silica, and its subsequent magnesiothermic reduction to porous silicon in the presence of a thermal moderator/porogen. In this presentation we focus on two distinct, yet complementary, issues. The first is the influence of plant component on the morphology of the resultant porous silicon. This is investigated for the case of equisetum telmatia, where we have evaluated the morphology and properties of porous silicon derived from the stem component of the plant separately from that from the fronds. A combination of electron microscopies (FESEM, TEM) along with low temperature nitrogen adsorption measurements (and corresponding BET surface area analyses) are used to characterize differences in nanostructure morphology that is produced from each type of plant material. The second issue is the ability of this plant-derived material to act as a carrier for the stabilization and delivery of otherwise metastable natural product-derived therapeutic species. As an example, we have evaluated the antibacterial activity of extracts of garlic loaded into porous silicon derived from tabasheer; such extracts have been reported in the literature to possess possible antimicrobial, antifungal, and cholesterol–lowering functions.2 Garlic consists of a complex mixture of sulfur containing components, dominated by the organosulfur compound allicin, that rapidly degrade (seconds) under ambient conditions. For these experiments, after determining the extent of extract loading of tabasheer-derived pSi with thermogravimetric analysis (TGA), a combination of agar disc diffusion as well as minimum inhibition concentration (MIC) methods are used to evaluate the antibacterial activity of drug-loaded pSi against Staphylococcus aureus. The ability of this particular plant-derived pSi is contrasted with the free extract as a function of time, thereby providing an assessment of this biogenic porous silicon carrier to extend the shelf life of an otherwise unstable active biogenic extract. Taken in concert, such experiments explore the utility and appeal of this low cost, naturally derived nanostructured porous matrix in higher volume controlled release applications. 1 L. Batchelor, A. Loni, L.T. Canham, M. Hasan, and J.L. Coffer, Silicon, 2012, 4, 259-266. 2 L.D. Lawson and Z.J. Wang, J. Agric. Food Chem. 2005, 53, 1974−1983.

Evaluation of zinc accumulation, allocation, and tolerance in Zea mays L. seedlings: implication for zinc phytoextraction.

This work investigated the accumulation, allocation, and impact of zinc (Zn; 1.0 μM-10 mM) in maize (Zea mays L.) seedlings under simulated laboratory conditions. Z. mays exhibited no significant change in its habitus (the physical characteristics of plants) up to 10-1000 μM of Zn (vs 5-10 mM Zn). Zn tolerance evaluation, based on the root test, indicated a high tolerance of Z. mays to both low and intermediate (or relatively high) concentrations of Zn, whereas this plant failed to tolerate 10 mM Zn and exhibited a 5-fold decrease in its Zn tolerance. Contingent to Zn treatment levels, Zn hampered the growth of axial organs and brought decreases in the leaf area, water regime, and biomass accumulation. Nevertheless, at elevated levels of Zn (10 mM), Zn(2+) was stored in the root cytoplasm and inhibited both axial organ growth and water regime. However, accumulation and allocation of Zn in Z. mays roots, studied herein employing X-ray fluorimeter and histochemical methods, were close to Zn accumulator plants. Overall, the study outcomes revealed Zn tolerance of Z. mays, and also implicate its potential role in Zn phytoextraction.

Diversity of Arbuscular Mycorrhizal Fungi Associated with a Sb Accumulator Plant, Ramie (Boehmeria nivea), in an Active Sb Mining.

Arbuscular mycorrhizal fungi (AMF) have great potential for assisting heavy metal hyperaccumulators in the remediation of contaminated soils. However, little information is available about the symbiosis of AMF associated with an antimony (Sb) accumulator plant under natural conditions. Therefore, the objective of this study was to investigate the colonization and molecular diversity of AMF associated with the Sb accumulator ramie (Boehmeria nivea) growing in Sb-contaminated soils. Four Sb mine spoils and one adjacent reference area were selected from Xikuangshan in southern China. PCR-DGGE was used to analyze the AMF community composition in ramie roots. Morphological identification was also used to analyze the species in the rhizosphere soil of ramie. Results obtained showed that mycorrhizal symbiosis was established successfully even in the most heavily polluted sites. From the unpolluted site Ref to the highest polluted site T4, the spore numbers and AMF diversity increased at first and then decreased. Colonization increased consistently with the increasing Sb concentrations in the soil. A total of 14 species were identified by morphological analysis. From the total number of species, 4 (29%) belonged to Glomus, 2 (14%) belonged to Acaulospora, 2 (14%) belonged to Funneliformis, 1 (7%) belonged to Claroideoglomus, 1 (7%) belonged to Gigaspora, 1 (7%) belonged to Paraglomus, 1 (7%) belonging to Rhizophagus, 1 (7%) belonging to Sclervocystis, and 1 (7%) belonged to Scutellospora. Some AMF sequences were present even in the most polluted site. Morphological identification and phylogenetic analysis both revealed that most species were affiliated withGlomus, suggesting that Glomus was the dominant genus in this AMF community. This study demonstrated that ramie associated with AMF may have great potential for remediation of Sb-contaminated soils.

Bioremediation of Heavy Metals from Soil and Aquatic Environment: An Overview of Principles and Criteria of Fundamental Processes

Heavy metals are natural constituents of the environment, but indiscriminate use for human purposes has altered their geochemical cycles and biochemical balance. This results in excess release of heavy metals such as cadmium, copper, lead, nickel, zinc etc. into natural resources like the soil and aquatic environments. Prolonged exposure and higher accumulation of such heavy metals can have deleterious health effects on human life and aquatic biota. The role of microorganisms and plants in biotransformation of heavy metals into nontoxic forms is well-documented, and understanding the molecular mechanism of metal accumulation has numerous biotechnological implications for bioremediation of metal-contaminated sites. In view of this, the present review investigates the abilities of microorganisms and plants in terms of tolerance and degradation of heavy metals. Also, advances in bioremediation technologies and strategies to explore these immense and valuable biological resources for bioremediation are discussed. An assessment of the current status of technology deployment and suggestions for future bioremediation research has also been included. Finally, there is a discussion of the genetic and molecular basis of metal tolerance in microbes, with special reference to the genomics of heavy metal accumulator plants and the identification of functional genes involved in tolerance and detoxification.

Effect of Different Concentrations of Nickel on Some secondary metabolites in Coriander (Coriandrum Sativum L.)

Nickel is a heavy metal that is toxic for humans, animals and plants. However, some plants are known as accumulator plants. In some plants, nickel has been introduced as beneficial element for growth and development. The aim of this study was to investigate the effect of different concentrations of nickel on some metabolites of Coriandrum Sativum L. The experiment was done under controlled conditions. Plant samples were kept in a growth chamber under standard conditions and treated with various concentrations of nickel for 12 weeks. Based on these results, leaf protein and sugar content decreased while the content of flavonoids, phenolic and flavonol increased.DOI: http://dx.doi.org/10.3126/ijls.v9i2.12059 International Journal of Life Sciences 9 (2) : 2015; 28-32

Heavy Metal Residues in Soil and Accumulation in Maize at Long-Term Wastewater Irrigation Area in Tongliao, China

Soil and plant samples were collected from Tongliao, China, during the maize growth cycle between May and October 2010. Heavy metals, such as Cr, Pb, Ni, and Zn, were analyzed. The concentrations of Cr, Pb, Ni, and Zn in the wastewater-irrigated area were higher than those in the topsoil from the groundwater-irrigated area. The concentrations of metals in the maize increased as follows: Pb < Ni < Zn < Cr. In addition, Cr, Pb, and Ni mainly accumulated in the maize roots, and Zn mainly accumulated in the maize fruit. The results of translocation factors (TF) and bioconcentration factors (BCF) of maize for heavy metals revealed that maize is an excluder plant and a potential accumulator plant and can serve as an ideal slope remediation plant. In addition, the increasing heavy metal contents in soils that have been polluted by wastewater irrigation must result in the accumulation of Cr, Pb, Ni, and Zn in maize. Thus, the pollution level can be decreased by harvesting and disposing of and recovering the plant material.

Response of Indian mustard (Brassica juncea) genotypes under different planting geometry

The experiment was conducted during rabi season of 2012–13 at Faizabad (Uttar Pradesh) to assess the response of different Indian mustard (Brassica juncea L. Czernj and Coss.) varieties under varied plant geometries. Mustard ‘Narendra rye-8501’ and planting geometry of 45 cm x 10 cm were observed to be best variety and optimum plant geometry, respectively as these treatments were superior over corresponding treatments (check varieties and plant geometries). This was corroborated from the similar significantly higher values of plant height, primary and secondary branches plant−1, number of leaves plant−1, dry matter accumulation plant−1, yields and other quality components recorded under the said treatments (mustard ‘Narendra rye-8501’ and row spacing of 45 cm x 10 cm). Highest benefit: cost ratio was also recorded under the above treatment combination.

PhytoremeDiation ofHeavyMetalsContaminated Environments: Screening forNativeAccumulatorPlants inZanjan-Iran

Environmental pollution with heavy metals is a global struggle. Phytoremediation is an effectiveand low-cost technology for refinement of polluted soils. This research was conducted in Zanjan province(located in North West Iran) where metallurgical industries are developed quickly. In this study, based on theheavy metals contamination of soil in the studied area six sampling sites were selected taking into account theindustrial distributions as well as the low/high traffic congestions. Leaves from eight tree species namely:Populus nigra, Ulmus pumila, Fraxinus excelsior, Robinia pseudoacacia, Acer hyracanum, Salix alba, Thujaorientalis, and Cupressus sempervirens var arizonica, were sampled and analyzed by ICP-OES (SpectroGenesis) for their heavy metal contents (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb). Results showed that heavymetals in stations close to the lead and zinc smelting industrial complexes are much higher than averageshowing a high correlation with their respective metal concentrations in soils. This clearly indicates that heavymetal contents in tree leaves in the studied area are solely related to industrial activities notably NationalIranian Lead and Zinc (NILZ) as well as Zinc Specialized Industrial Complex (ZSIC) companies. Based on theresults, the studied native plants accumulate different metals selectively and Populus nigra was found to bethe best accumulator plant for Mn, Zn and Cd, Thuja orientalis, as the best phytoextractor for Fe, andCupressus sempervirens var arizonica is the best species among the studied native plants for accumulation ofPb.

Feasibility Study of Phragmites karka and Christella dentata Grown in West Bengal as Arsenic Accumulator

A survey was undertaken, in arsenic (As) contaminated area of the Nadia district, West Bengal, India, to find native As accumulator plants. As was determined both in soil and plant parts. The results showed that the mean translocation factor of Pteris vittata L, Phragmites karka (Cav.) Trin. Ex. Steud and Christella dentata Forssk were higher than 1. It thus appeared that these plants can be efficient accumulators of As.Phytoremediation ability of C. dentata and P. karka was evaluated and compared with known As-hyperaccumulators -P. vittata and Adiantum capillus veneris L. Plants were grown in the As spiked soil (25, 50, 75 and 100 mg kg−1). As accumulation was found to be highest in P. vittata, 117.18 mg kg−1 in leaf at 100 mg kg−1 As treatment, followed by A. capillus veneris, P. karka and C. dentata being 74, 83.87 and 40.36 mg kg−1, respectively. Lipid peroxidation increased after As exposure in all plants. However, the antioxidant enzyme activity and molecules concentration also increased which helped the plants to overcome As-induced oxidative stress. The study indicates that P. karka and C. dentata could be considered as As-accumulators and find application for As-phytoextraction in field conditions.

Selenium distribution and speciation in plant parts of wheat (Triticum aestivum) and Indian mustard (Brassica juncea) from a seleniferous area of Punjab, India

The concentration, distribution, and speciation of selenium in different parts of wheat and Indian mustard, grown in a seleniferous area in Punjab, were investigated using synchrotron based (XAS) and classical acid digestion and extraction methods.The analyses revealed a high Se enrichment in all investigated plant parts, with Se levels in the range of 133–931mg/kg (dry weight, dw). Such high Se enrichment is mainly due to the considerable amounts of easily available Se detected in the soil, which are renewed on a yearly basis to some extent via irrigation. Speciation analysis in soil and plants indicated selenate and organic Se as major Se species taken up by plants, with a minor presence of selenite. The analyses also revealed that the highest Se enrichment occurs in the upper plant parts, in agreement with the high uptake rate and mobility of selenate within plants. In both wheat and mustard, highest Se enrichments were found in leaves (387mg/kg·dw in wheat and 931mg/kg·dw in mustard). Organic species (dimethylselenide and methylselenocysteine) were found in different parts of both plants, indicating that an active detoxification response to the high Se uptake is taking place through methylation and/or volatilization. The high proportion of selenate in wheat and mustard leaves (47% and 70%, respectively) is the result of the inability of the plant metabolism to completely transform selenate to non-toxic organic forms, if oversupplied. Methylselenocysteine, a common Se species in accumulating plants, was detected in wheat, suggesting that, in the presence of high Se concentration, this plant develops similar response mechanisms to accumulator plants.

Impact of rice cultivar and organ on elemental composition of phytoliths and the release of bio-available silicon.

The continental bio-cycling of silicon (Si) plays a key role in global Si cycle and as such partly controls global carbon (C) budget through nutrition of marine and terrestrial biota, accumulation of phytolith-occluded organic carbon (PhytOC) and weathering of silicate minerals. Despite the key role of elemental composition of phytoliths on their solubility in soils, the impact of plant cultivar and organ on the elemental composition of phytoliths in Si high-accumulator plants, such as rice (Oryza sativa) is not yet fully understood. Here we show that rice cultivar significantly impacts the elemental composition of phytoliths (Si, Al, Fe, and C) in different organs of the shoot system (grains, sheath, leaf and stem). The amount of occluded OC within phytoliths is affected by contents of Si, Al, and Fe in plants, while independent of the element composition of phytoliths. Our data document, for different cultivars, higher bio-available Si release from phytoliths of leaves and sheaths, which are characterized by higher enrichment with Al and Fe (i.e., lower Si/Al and Si/Fe ratios), compared to grains and stems. We indicate that phytolith solubility in soils may be controlled by rice cultivar and type of organs. Our results highlight that the role of the morphology, the hydration rate and the chemical composition in the solubility of phytoliths and the kinetic release of Si in soil solution needs to be studied further. This is central to a better understanding of the impact of soil amendment with different plant organs and cultivars on soil OC stock and on the delivery of dissolved Si as we show that sheath and leaf rice organs are both characterized by higher content of OC occluded in phytolith and higher phytolith solubility compared to grains and stems. Our study shows the importance of studying the impact of the agro-management on the evolution of sinks and sources of Si and C in soils used for Si-high accumulator plants.

Elemental Composition Analysis of Plants and Composts Used for Soil Remediation by Laser‐Induced Breakdown Spectroscopy

Laser‐induced breakdown spectroscopy (LIBS) is a fast and reliable technique suitable for the simultaneous qualitative and quantitative analysis of major and trace elements in samples of various nature and origin. In last decades, the use of metal accumulator plants, in combination with compost, has become a cheap and sustainable alternative technique to lower soil contamination by toxic heavy metals. In the present work, the LIBS technique has been applied to measure the concentrations of selected elements, including Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Pb, Sr, and Zn, in two composts of different origin and nature and four accumulator plant species (Atriplex halimus, Brassica alba, Brassica napus, and Eruca vesicaria). The plant samples were analyzed either as bulk plant material or as specific organs (i.e. shoots and roots). The concentrations measured by LIBS were assessed by complementary induced coupled plasma‐optical emission spectroscopy. The significant correlation found between the data obtained by the two techniques (R = 0.732–0.999) supports the feasibility of LIBS for fast screening of major, trace and toxic elements in plant and compost samples. In conclusion, the LIBS technique shows promising for further applications in soil remediation as well as in agriculture.

Identification of effective Pb resistant bacteria isolated from Lens culinaris growing in lead contaminated soils.

Soil bacteria are a new phytoremediation system for the removal of heavy metals from soils. In this study, fifteen soil bacteria were isolated from root nodules of lentil growing in heavy metals contaminated soils, particularly by lead. Molecular characterization of the collection showed a large diversity, including Agrobacterium tumefaciens, Rahnella aquatilis, Pseudomonas, and Rhizobium sp. These soil bacteria had a wide range of tolerance to heavy metals. Among them, strains of A. tumefaciens and R. aquatilis tolerated up to 3.35 mM Pb; whereas Pseudomonas tolerated up to 3.24 mM Pb. The inoculation of lentil grown hydroponically with inoculums formed by these efficient and Pb resistant bacteria enhanced plant biomass. The treatment of this symbiosis by 1 mM Pb for 10 days or by 2 mM Pb for 3 days demonstrated that lentil had Pb accumulation capacity and can be considered a Pb accumulator plant, elsewhere, roots accumulated more Pb than shoots, and the inoculation decreased the Pb up take by the plants, suggesting that this symbiosis should be investigated for use in phytostabilization of Pb-contaminated soils. At the same time, a modulation in the antioxidant enzyme activity and a specific duration was required for the induction of the superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX) response and to adapt to Pb stress. These results suggested that these enzymes may be involved in the main mechanism of antioxidative defense in lentil exposed to Pb oxidative stress.

Remediation of heavy metal contaminated ecosystem: an overview on technology advancement

The issue of heavy metal pollution is very much concerned because of their toxicity for plant, animal and human beings and their lack of biodegradability. Excess concentrations of heavy metals have adverse effects on plant metabolic activities hence affect the food production, quantitatively and qualitatively. Heavy metal when reaches human tissues through various absorption pathways such as direct ingestion, dermal contact, diet through the soil–food chain, inhalation and oral intake may seriously affect their health. Therefore, several management practices are being applied to minimize metal toxicity by attenuating the availability of metal to the plants. Some of the traditional methods are either extremely costly or they are simply applied to isolate contaminated site. The biology-based technology like use of hypermetal accumulator plants occurring naturally or created by transgenic technology, in recent years draws great attention to remediate heavy metal contamination. Recently, applications of nanoparticle for metal remediation are also attracting great research interest due to their exceptional adsorption and mechanical properties and unique electrical property, highly chemical stability, and large specific surface area. Thus, the present review deals with different management approaches to reduce level of metal contamination in soil and finally to the food chain.

The effect of delay cultivation on dry matter accumulation and chickpea yield in dry land conditions

Plant yield as a result of the allocation of the photosynthesis material to economic organs is that was obtained through balanced relationships between source and the tank. Exact and correct of physiological processes understanding of controlling yield and proper use of them will be caused to increase crop plants yield. In this case the experiment was done in Islamic Azad University of Kermanshah in 2011. In this study, three cultivars of chickpea such as Flip93-93, 12-60-31 and Hashem in three planting dates such as fall, expended and spring (delay) were compared with complete random blocks factorial in 4 repetitions. Growth indicators such as: total dry matter (TDM), stem dry matter accumulation (SDM), leaf dry matter accumulation (LDM), pod dry matter accumulation (PDM) and grain dry matter accumulation (GDM) plant height, number of seeds per plant, 100seed weight, biological yield, harvest index and grain yield were evaluated. Flip93-93 cultivar in fall cultivation had the highest dry matter accumulation of leaf, stem and the whole plant. Meanwhile Hashem cultivar had the least dry matter accumulation in all of the indexes. Reducing the dry matter accumulation in total plant in delay cultivation (spring) rather than fall cultivation in Flip93-93, 12-60-31 and Hashem in order, were 145, 23, and 47%, which show that superiority of fall cultivation rather than spring cultivation. Finally Flip93-93 cultivar in fall cultivation (1002.1 Kg/ha) had the highest and 12-60-31 cultivar in delay cultivation (336.52 Kg/ha) had the least seed yield.