Concentrations In Plant Tissues Research Articles

Bacteria associated with Zn-hyperaccumulators Arabidopsis halleri and Arabidopsis arenosa from Zn–Pb–Cd waste heaps in Poland as promising tools for bioremediation

To identify metal adapted bacteria equipped with traits positively influencing the growth of two hyperaccumulator plant species Arabidopsis arenosa and Arabidopsis halleri, we isolated bacteria inhabiting rhizosphere and vegetative tissues (roots, basal and stem leaves) of plants growing on two old Zn–Pb–Cd waste heaps in Bolesław and Bukowno (S. Poland), and characterized their potential plant growth promoting (PGP) traits as well as determined metal concentrations in rhizosphere and plant tissues. To determine taxonomic position of 144 bacterial isolates, 16S rDNA Sanger sequencing was used. A metabolic characterization of isolated strains was performed in vitro using PGP tests. A. arenosa and A. halleri accumulate high amounts of Zn in their tissues, especially in stem leaves. Among in total 22 identified bacterial taxa, the highest level of the taxonomical diversity (H’ = 2.01) was revealed in A. halleri basal leaf endophytes originating from Bukowno waste heap area. The 96, 98, 99, and 98% of investigated strains showed tolerant to Cd, Zn, Pb and Cu, respectively. Generally, higher percentages of bacteria could synthesize auxins, siderophores, and acetoin as well as could solubilize phosphate. Nine of waste heap origin bacterial strains were tolerant to toxic metals, showed in vitro PGP traits and are potential candidates for bioremediation.

Effect of Application Different Combinations of Phosphogypsum and Humic Acids Mixed With Saline Irrigation Water on Broccoli Yield and NPK Concentration

Long-term irrigation with saline water causes detrimental effects on the soil-crop system. The study aimed to determine the best combination of Phosphogypsum and humic acid can mitigate the negative effects of saline water irrigation on broccoli growth. Therefore, two-factorial field experiment was conducted according to a randomized complete block design with three replications during autumn season of 2021 in Fallujah district /Anbar governorate in sandy loam soil. The first factor included three levels of saline water irrigation, namely 2.5, 5.0 and 7.0 dS.m-1. while the second factor involved three levels of humic acids i.e., 0.0, 0.25 and 0.50 g/l mixed with three levels of phosphogypsum that is 0.0, 0.25 and 0.50 g/l. Fruits weight, height, yield, plant nitrogen content, plant phosphorus, and plant potassium content were measured. The results showed that the combinations under study ( humic acids and phosphogypsum) had a crucial role in reducing the negative effects of irrigation salinity. Moreover, the macronutrients availability increased with increasing humic acids concentration in irrigation water. The observed results show a significant increase in the weight of broccoli fruit and yield at T8 by giving 325 g. plant-1and 8.66 t.h-1 respectively under effect of the combination under study. Also, the studied combinations led to increase the N,P,and K concentration in plant tissues. Where the highest observed averages of nitrogen and potassium were 3.96% and 2.56% at T8 treatment. While The highest concentration of phosphorus was observed at treatment T9 reached 0.47%.

Arbuscular mycorrhizal fungi and nitric oxide alleviate cadmium phytotoxicity by improving internal detoxification mechanisms of corn plants.

Plants develop several external and internal mechanisms to increase their tolerance to heavy metals (HMs) toxicity including cadmium (Cd). Symbiosis with arbuscular mycorrhizae fungi (AMF) is one of the plants' strategies to tolerate HMs toxicity. Nitric oxide (NO), as a signaling molecule, is also involved in physiological responses of plants to various stresses. The present work was conducted as a factorial completely randomized design with three replications to study the effects of Funneliformis mosseae fungi and Sodium nitroprusside (SNP, 100 mM) as a donor of NO alone, in combination (AMF + SNP) on corn plant growth, and internal detoxification mechanisms of Cd toxicity in a Cd-contaminated calcareous soil (0, 25, 50, and 100 mg Cd kg-1). The results showed that under Cd stress, AMF inoculation and/or foliar application of SNP significantly increased plant growth (32% to 103% for shoot and 44% to 84% for root) by decreasing Cd concentration in corn plant tissues (23% to 46% for shoot and 19% to 40% for root). Cd-induced oxidative stress was mitigated by AMF and/or SNP by enhancing the activities of antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), and concentration of non-enzymatic antioxidants such as glutathione (GSH) and phytochelatin (PC). Increasing the tolerance index (TI) and decreasing the transfer factor (TF) in the corn plants treated with AMF and/or SNP, confirm the efficient role of SNP and AMF in stimulating the detoxification mechanisms of Cd within the plant cells, which was more pronounced at the lowest Cd level (25 mg Cd kg-1). In conclusion, symbiotic associations of corn plants with AMF alone or in combination with SNP mitigated the detrimental effect of Cd toxicity in corn grown in Cd-contaminated calcareous soil. The corn's internal detoxification mechanisms lowered the Cd concentration in plant tissue which resulted in the improvement of the corn's growth parameters.

Intercropping of kenaf and soybean affects plant growth, antioxidant capacity, and uptake of cadmium and lead in contaminated mining soil.

Intercropping is considered a sustainable agricultural practice that can reduce the environmental impacts on agriculture. Our study investigated the morphology, physiology, and cadmium (Cd) and lead (Pb) uptake of kenaf (Hibiscus cannabinus L.) and soybean (Glycine max L.) under intercropping in mining soil. Results showed that mutual intercropping is conducive to the growth and biomass accumulation of kenaf and soybean, compared to their respective monoculture. Intercropping increased the relative chlorophyll index in kenaf, while that in soybean had no significant effect. Furthermore, intercropping increased the antioxidant enzyme activity of kenaf, while that of soybean reduced or had no significant effect. The content of malondialdehyde (MDA) was decreased in both of the species. Compared to their respective monoculture, Cd content was increased in kenaf leaves and reduced in soybean roots. Moreover, intercropping decreased the Pb content in tissues of both the species, except that Pb content of kenaf roots was increased. At the same time, root, leaf, or stem bioconcentration factors also performed the same trend, and TF was less than 1. These results indicated that intercropping can increase the plant growth and decrease the metal content in plant tissues. Present findings could provide support for future research on kenaf and soybean cultivation in contaminated lands. In addition, the present study strengthens our understanding about the effectiveness of intercropping system on heavy metal-contaminated lands for sustainable agricultural production.

Species phylogeny, ecology, and root traits as predictors of root exudate composition.

Root traits including root exudates are key factors affecting plant interactions with soil and thus play an important role in determining ecosystem processes. The drivers of their variation, however, remain poorly understood. We determined the relative importance of phylogeny and species ecology in determining root traits and analyzed the extent to which root exudate composition can be predicted by other root traits. We measured different root morphological and biochemical traits (including exudate profiles) of 65 plant species grown in a controlled system. We tested phylogenetic conservatism in traits and disentangled the individual and overlapping effects of phylogeny and species ecology on traits. We also predicted root exudate composition using other root traits. Phylogenetic signal differed greatly among root traits, with the strongest signal in phenol content in plant tissues. Interspecific variation in root traits was partly explained by species ecology, but phylogeny was more important in most cases. Species exudate composition could be partly predicted by specific root length, root dry matter content, root biomass, and root diameter, but a large part of variation remained unexplained. In conclusion, root exudation cannot be easily predicted based on other root traits and more comparative data on root exudation are needed to understand their diversity.

Heavy metals and nutrients removal in a batch-fed greywater treatment system planted with Canna indica and Oryza sativa L.

The objective of this investigation was to determine whether Canna indica and Oryza sativa L. plants have the phytoremediation potential for removing heavy metals and nutrients from greywater treated in batch-fed Horizontal sub-surface Flow Constructed Wetlands (HssFCW). The HssFCW had a Hydraulic Retention Time (HRT) and organic loading rate (OLR) of 3 days and 3.96 (g.BOD/m2.day) respectively. Greywater (GW) samples were characterized for electrical conductivity (EC), total nitrogen (TN), total phosphorous (TP), pH, sodium adsorption ratio (SAR), metals (Al, Fe, Mg, Ca) and Biochemical Oxygen Demand (BOD5). The accumulation of metals in the soil and edible parts of plants was evaluated in terms of bioconcentration and translocation factors. Metal concentrations were determined using an atomic absorption spectrometer, while nutrients were by colorimetric method. The result shows that the metals and nutrients were below the WHO allowable limit for treated greywater recycling in agriculture. Nutrient removal was insignificantly different while metal removal was significantly different in the constructed wetlands (CW). The results indicated that C. indica is preferred as a perennial plant with unlimited metal accumulation and high nutrient removals compare to O. sativa L. with a high metal concentration in the above-ground plant tissue and also an annual plant.

Generalizing routes of plant exposure to pesticides by plant uptake models to assess pesticide application efficiency

Pesticide application techniques are critical not only for integrated pest management (IPM) but also for food and environmental safety. Assessing pesticide application efficiency on plants can help optimize IPM and reduce pesticide environmental impacts. With hundreds of pesticides registered for use in agriculture, this study proposed a modeling approach based on plant uptake models for generalizing routes of plant chemical exposures that can correspond to different types of pesticide application methods and evaluating their respective efficiency on plants. Three representative pesticide application methods (i.e., drip irrigation, foliar spray, and broadcast application) were selected for modeling simulations. The simulation results for three representative pesticides (i.e., halofenozide, pymetrozine, and paraquat) revealed that the soil-based transpiration exposure route facilitated the bioaccumulation of moderately lipophilic compounds in leaves and fruits. While the plant surface-based exposure route (i.e., leaf cuticle penetration) made it easier for highly lipophilic compounds to enter plants, moderately lipophilic pesticides (i.e., log KOW ∼ 2) were more soluble in phloem sap, which enhanced their subsequent transport within plant tissues. In general, moderately lipophilic pesticides had the highest simulated residue concentrations in plant tissues for the three specific application methods, indicating they had the highest application efficiency due to their enhanced uptake routes (via transpiration and surface penetration) and increased solubility in xylem and phloem saps. Compared to foliar spray and broadcast application, drip irrigation produced higher residue concentrations for a wide variety of pesticides, exhibiting the highest application efficiency for many pesticides, especially for moderately lipophilic compounds. Future research should incorporate plant growth stages, crop safety, pesticide formulations, and multiple application events into the modeling approach for understanding pesticide application efficiency evaluation.

Modeling pesticide dissipation half-lives in plants with effects of fertilizer application: A flexible simulation tool

Fertilizer is commonly applied to plants alongside pesticides, which can significantly affect pesticide dissipation behavior in plants. Taking into account the fertilizer effect when modeling pesticide dissipation from plants is crucial for accurately predicting pesticide residue levels in crops, which is essential for ensuring agricultural food safety, conducting consumer exposure assessments, and protecting environmental health. However, mechanistic modeling approaches for estimating dissipation half-lives in plants while taking fertilizer application into account are currently lacking. To address this research gap, we simulate pesticide dissipation half-lives using mechanistic models, and the method can be tabulated in spreadsheets to help users perform modeling exercises by modifying fertilizer application conditions. In addition, a spreadsheet simulation tool with a step-by-step procedure is provided, allowing users to easily estimate pesticide dissipation half-lives in plants. The simulation results for the cucumber plant demonstrated that plant growth dynamics played a significant role in the overall elimination kinetics for the majority of pesticides, indicating that fertilizer application could significantly affect pesticide dissipation half-lives in plants. On the other hand, some moderately or highly lipophilic pesticides may reach their peak concentrations in plant tissues over a longer period of time following pesticide application, depending on their uptake kinetics and dissipation rates on plant surfaces or soil. Therefore, the first-order dissipation kinetic model, which generated pesticide dissipation half-lives in plant tissues, must be fine-tuned with respect to its initial concentrations. With chemical-, plant-, and growth-specific model inputs, the proposed spreadsheet-based operational tool can assist users in estimating pesticide dissipation half-lives in plants with fertilizer application effects. To enhance the effectiveness of our modeling approach, it is recommended that future research investigate rate constants for other types of plant growth dynamics, chemical degradation, horticultural methods, and environmental conditions (such as temperature). These processes can be characterized using first-order kinetic rate constants as model inputs in the operational tool, which can significantly improve the simulation results.

Efficient Agrobacterium tumefaciens-mediated genetic transformation of Aloe vera

Genetic transformation of plants has emerged as a core research tool for the functional characterization of genes and cultivar improvement in the field of plant biology. Effectually, high transformation efficiency is a prerequisite for accomplishing the stated targets. Aloe vera, a tropical cactus plant in distinction to the family Liliaceae, has seized a long history of secular acceptance as a therapeutic agent and is reasonably the most popular herbal remedy these days. However, the genetic transformation efficiency of Aloe vera is relatively low and seldom reported formerly. This study aims to optimize Agrobacterium-mediated transformation in Aloe vera by refining several parameters like explant selection, the extent of explant injury during infection, Agrobacterium concentration, co-cultivation pH, and duration and desiccation of plant tissue to improve the infection efficiency. The results showed that nearly 83% transient transformation efficiency was attained by suspending the Agrobacterium tumefaciens (AGL1 strain) cells at a concentration of OD600: 0.4 in co-cultivation media at pH-5.6 to infect the stem of aloe by desiccation, followed by 3 days of co-cultivation. Desiccation during infection had proved to enhance T-DNA delivery, whereas a higher extent of explant injury was found to curtail the infection efficiency. The molecular analysis of the putative transformants was carried out by following GUS histochemical assay and PCR. Thereupon, Southern blotting was used to substantiate the authentication of positive transgenic plants and analyze the copy number of the hptII gene in the Aloe vera genome. A transformation efficiency of over 2% was obtained, which is higher than the previous report. This study bestows an improved Agrobacterium-mediated transformation protocol based on desiccation in Aloe vera, which might help in facilitating various functional genomic studies and gene regulation in the aloe plant, eventually allowing the genetic modification of aloe species in an effective manner. This research deliberates a meliorated Agrobacterium-mediated transformation methodology for Aloe vera, which may facilitate various gene functional investigations and bioengineering of aloe species in an effective salutary way.

IMPACT OF SIDEROPHORE PRODUCING RHIZOBACTERIA ON GROWTH AND IRON CONTENT IN POTATO

Iron deficiency is a prevalent nutritional disorder that has a significant impact on a large population worldwide. Malnutrition can potentially be mitigated through the implementation of biofortification, a method aimed at enhancing the micronutrient content of staple food items. Plant growth promoting rhizobacteria (PGPR) possess the capacity to enhance the iron concentration in consumable plant tissues by enhancing its availability through various mechanisms. A controlled experiment was conducted to evaluate the capacity of five bacterial isolates (Z1, Z2, Z3, Z4, Z5, Z6) to promote plant growth and enhance the bioavailability of iron (Fe) in potato plants. The iron was administered via a solution that consisted of iron sulphate. The study's results demonstrate that the utilization of PGPR led to a notable enhancement in multiple growth parameters of the plants, encompassing plant height, root length, root fresh and dry weights, shoot fresh and dry weights, and iron content, in comparison to plants that did not undergo PGPR inoculation. The application of FeSO4 led to a significant increase in the concentration of Fe, with a respective rise of 100% and 173% observed in the grain and shoot, in comparison to the control group. The application of Plant Growth Promoting Rhizobacteria (PGPR) in combination with iron led to a substantial improvement in the levels of iron in both grain and shoot tissues. Specifically, there was a notable increase of 78.64% in grain iron content and a 63.24% increase in shoot iron content, as compared to the control group. The results of this study suggest that the utilization of plant growth-promoting rhizobacteria (PGPR) can augment the absorption of iron (Fe) by plants in the presence of supplementary Fe in the soil. The results of this study indicate that the implementation of microbial assisted biofortification in potato tuber holds promise for addressing micronutrient deficiency in human populations, particularly in regions with limited access to resources.

Phosphogypsum impacts on soil chemical properties and vegetation tissue following reclamation.

Phosphogypsum (PG) is a by-product of phosphorus fertilizer that is typically stacked near production sites. Phosphogypsum contains trace elements and naturally occurring radioactive materials which may be hazardous to the surrounding environment. Phosphogypsum stack reclamation typically involves placing a soil cap and seeding grass to create a barrier for reducing environmental impacts; using woody species is uncommon. This study used three soil treatments with grass and woody species to determine whether mixing PG with soil affects soil chemical properties, and metal and radionuclide concentrations in tissue. None of the elements in soil was above Canadian guidelines for industrial land use. Aluminum, beryllium, chromium, copper, iron, magnesium, manganese, nickel, and vanadium were significantly higher in both study and reference sites than in pure PG; cadmium, calcium, fluoride, and strontium were significantly higher in pure PG. There was a poor correlation between soil and plant concentrations for most elements indicating trace elements were not in a bioavailable form. Trace elemental concentrations in plant tissue generally differed significantly with vegetation type but not within similar species. Trace elements and isotopes in PG were not high enough to affect plant growth. Among the isotopes, 222Ra emissions differed significantly with vegetation covers; activity of 226Ra in pure PG was above Canadian guidelines, but lower in vegetation tissue. This study suggests 15cm soil mixed with PG can be used for PG stack revegetation when fast-growing Salix and Populus species are used in reclamation.

Influences of peanut hull-derived biochar, Trichoderma harzianum and supplemental phosphorus on hairy vetch growth in Pb- and Zn-contaminated soil.

In the present study, in order to improve the growth performance of hairy vetch (Vicia villosa Roth., Local landrace from Ardabil, Iran) seedlings grown in the soil contaminated with heavy metals Pb and Zn, our attention was directed toward the application of biochar, inoculation with conidial suspension of Trichoderma harzianum Rifai-T22 and management of phosphorus (P) nutrition. Heavy metal toxicity reduced leaf greenness, membrane stability index, maximum quantum yield of PSΙΙ (Fv/Fm), P concentration and uptake in plant tissues and root and shoot biomass, but increased Pb and Zn concentration and uptake in root and leaf, H2O2 and malondialdehyde content and CAT and POX activity in the leaves. The application of biochar, inoculation with Trichoderma fungus and P supplementation increased the shoot P content, which might contribute to the alleviation of P insufficiency and a subsequent elevation in P transfer to aboveground biomass, and eliminated the toxicity of heavy metal on hairy vetch plants, which was revealed in reducing oxidative stress and enhancing plant growth performance. The biochar considerably increased Zn immobilization, while being able to slightly stabilize Pb. Co-application of Trichoderma and 22mg P/kg soil (22P) increased the concentration and uptake of Zn in the roots and decreased the translocation of this element to the shoots, especially when biochar was not amended. Although the biochar and P inputs could compensate the negative Trichoderma effects, the results suggested that biochar application in combination with fungal inoculation and 22-P supplementation could not only increase hairy vetch growth performance but also decline heavy metal uptake to ensure the production of a forage crop in soils polluted with heavy metals based on the nutritional standards of livestock.

Influence of Beneficial Bacterial Inoculation on Nitrogen Concentration and Tomato Seedling Growth Under Glasshouse Conditions

Many types of soil bacteria through antagonistic activity, thrive in the rhizosphere of plants or surround the tissues of plants and encourage plant development and reduce the nematode population. Bacteria as such are commonly known as Plant Growth-Promoting Rhizobacteria (PGPR). The purpose of this research was to determine Bacillus spp. inoculations impact on tomato seedling development with varying rates of chemical nitrogen-fertilizer. To minimize the recommended quantity of N fertilizer for tomato seedling development, a small pot experiment with selected PGPB was undertaken with varying amount of N fertilizer. Plant growth-promoting bacteria (PGPB) labeled as UPMB10 and UPMRB9 (identified as Bacillus subtilis and Bacillus tequilensis, respectively) were utilized as microbial inoculants because they showed a significant improvement in seedling growth and N concentration in tomato plant tissues in a pot culture investigation. These microbial inoculants significantly improved the development of the plants, stem length, root length, leaves number, dry weight of shoots (stem, leaves), dry weight of roots, SPAD value, N concentration in tissues, and soil bacterial population. Bacteria-treated seedlings with 50% N fertilizer significantly increased stem length (69.07%), root length (78.51%), leaves number (68.58%), shoots (92.45%, 90.39%, stem and leaves, respectively), roots (73.33%), SPAD value (50.31%), and N concentration in plant tissues (63.79%) as compared to the uninoculated control. The findings also showed that inoculation of the Bacillus spp. tomato seedlings could save up to 50 percent of the recommended rate of chemical N fertilizer without affecting tomato seedling growth. The findings of this study suggest that the amount of nitrogen fertilizer given during tomato seedling development can be reduced by half, resulting in increased soil health and reduced environmental pollution.

Effect of crude oil pollution on heavy metal content and GST gene expression of Mucuna pruriens

The study investigated the effect of crude oil pollution on the heavy metal content and gene expression of Mucuna pruriens. Varying amounts of crude oil (0ml, 200ml, 400ml, 800ml and 1000ml) were used to pollute 10kg bags of loam soil, onto which Mucuna pruriens seeds were planted for 8 weeks. Data were collected for heavy metal content of plant tissues and GST gene expression. The highest heavy metal content of the plant tissue was observed at the 800ml treatment (0.0135 g kg-1, 0.074 g kg-1, and 0.0211 g kg-1) and the least was observed for the control treatment (0.0049 g kg-1, 0.034 g kg-1 and 0.0142 g kg-1), thus showing percentage increments of 175.51%, 117.65%, and 48.59% for the copper, zinc, and nickel content respectively. This showed that the increment of crude oil pollution in the soil led to a seemingly dose-dependent increment of heavy metal content of the plant tissue. The normalized expression levels of the target gene (GST) in the calibrator (control) sample “A”, and that of the treated/polluted (test) sample “B” were established as 0.150726 and 0.145592 respectively; and, it was established that there was no significant change in the normalized expression levels of the target gene (GST) in both the control (calibrator) sample and the treated/polluted (test) sample. Crude oil treatment of M. pruriens, despite showing reductions in the morphological parameters and increments in the heavy metal content of the tissues, didn’t affect the expression of the target GST gene, as was evident in the absence of significant difference in the normalized expression levels of the target gene (GST) in both the control (calibrator) sample and the treated/polluted (test) sample. Considering the resilience of M. pruriens and its ability to adapt to the high amounts of crude oil in the soil, it is advised that it be employed in the possible phyto-extraction of crude oil and/or phyto-remediation in crude oil polluted soils.

Investigations Concerning Heavy Metals Dynamics in Reynoutria japonica Houtt.-Soil Interactions.

Reynoutria japonica Houtt (RJ) is an extremely invasive plant species, found nowadays in a wide range of habitats, including those polluted with heavy metals (HM). The aim of this study was to investigate HM dynamics in RJ-soil interactions in five habitats historically polluted with HM located in Baia Mare city, Romania. The concentrations of major metal elements (Cd, Cu, Pb, Zn) in plant tissues (roots, stems, leaves) and soil samples collected from the study sites were analyzed via portable ED-XRF spectroscopy (converted), and the translocation factor (TF) and bioconcentration factor (BCF) were calculated. The mean values of HM in soil samples collected from the study sites exceeded the threshold limit values established by Romanian legislation. Generally, the highest concentration of Cd was recorded in the above-ground part of the plant (stem and leaves), while for Cu, Pb and Zn, the highest values (with few exceptions) were recorded in the root. The metal transfer was highly effective from soil to RJ, such that all four of the HM studied exceeded the normal range of metals in a plant. Analysis of metal concentrations in plant tissues showed an efficient movement of Cd and Zn to the above-ground parts of the plant, a tendency particularly pronounced in the case of Cd (TF and BCF > 1), while Pb was the least bioaccumulated HM. It may be concluded that RJ is able to tolerate high concentrations of HM, being a good phytoextractor for Cd and Zn.

Reassessing the claimed cytokinin-substituting activity of dehydrodiconiferyl alcohol glucoside

Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with reported cytokinin-substituting and cell-division-promoting activity. Despite its claimed activity, DCG did not trigger morphological changes in Arabidopsis seedlings nor did it alter transcriptional shifts in cell division and cytokinin-responsive genes. In reinvestigating the bioactivity of DCG in its original setting, the previously described stimulation of tobacco callus formation could not be confirmed. No evidence was found that DCG is actually taken up by plant cells, which could explain the absence of any observable activity in the performed experiments. The DCG content in plant tissue increased when feeding explants with the DCG aglycone dehydrodiconiferyl alcohol, which is readily taken up and converted to DCG by plant cells. Despite the increased DCG content, no activity for this metabolite could be demonstrated. Our results therefore demand a reevaluation of the often-quoted cytokinin-substituting and cell-division-promoting activity that has previously been attributed to this metabolite.

Enrichment and distribution characteristics of heavy metal(loid)s in native plants of abandoned farmlands in sewage irrigation area.

Soil samples and native plants were collected from abandoned farmlands with a long history of sewage irrigation along Dongdagou stream, Baiyin City. We investigated the concentrations of heavy metal(loid)s (HMMs) in soil-plant system to evaluate the accumulation and transportation ability of HMMs in native plants. Results indicated that soils in study area were severely polluted by Cd, Pb, and As. With the exception of Cd, the correlation between total HMM concentrations in soil and plant tissues was poor. Among all investigated plants, no one was close to the criteria for the HMM concentrations of hyperaccumulators. The concentrations of HMMs in most plants were reached the phytotoxic level and the abandoned farmlands could not be used as forages, which showed that native plants may possess resistance capabilities or high tolerance for As, Cu, Cd, Pb, and Zn. The FTIR (Fourier transform infrared spectrometer) results suggested that the detoxification of HMMs in plants may depend on the functional groups (-OH, C-H, C-O, and N-H) of some compounds. Bioaccumulation factor (BAF), bioconcentration factor (BCF), and biological transfer factor (BTF) were used to identify the accumulation and translocation characteristics of HMMs by native plants. S. glauca had the highest mean values of BTF for Cd (8.07) and Zn (4.75). C. virgata showed the highest mean BAFs for Cd (2.76) and Zn (9.43). P. harmala, A. tataricus, and A. anethifolia also presented high accumulation and translocation abilities for Cd and Zn. High HMMs (As, Cu, Cd, Pb, and Zn) accumulation in the aerial parts of plants may lead to increased accumulation of HMMs in the food chain; additional research is desperately required. This study demonstrated the HM enrichment characteristics of weeds and provided a basis for the management of abandoned farmlands.

Plant Growth Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi Combined Application Reveals Enhanced Soil Fertility and Rice Production

Rice (Oryza sativa L.) is an important crop that is grown worldwide to supply the world’s expanding food demand. In the current study, the effects of plant growth-promoting rhizobacteria (PGPR) and Arbuscular mycorrhizal fungi (AMF) on soil fertility and rice growth were explored. Rice plants were inoculated to evaluate how AMF fungi and PGPR affect various aspects of soil and plants, implicating abiotic stress tolerances. The experiment was carried out in a completely randomized design with three replicates under the controlled conditions. Results depicted that the plants that were inoculated with a mixture of AMF and PGPR had better yields and nutritional concentrations, while both AMF and PGPR lowered soil pH and organic matter differently. Similarly, AMF and PGPR treatments significantly increased the amount of N, P, K, and B in the post-harvest soil. The PGPR-inoculated plants had a 10–40% higher buildup of N in their tissues. Similarly, when they were compared with non-infected plants, AMF-inoculated treatments demonstrated a greater N accumulation in the rice tissue. The maximum P content in plant tissues was 0.149% in PGPR5-infected plants, either alone or in combination with AMF. In T12, AMF + PGPR5 inoculated rice plants, the maximum K uptake was 1.98%, which was 54% higher than the control treatment. The sole application of AMF raised K buildup in rice tissues by 38% compared with the control treatment. The improved productivity of plants with AMF and PGPR (especially with PGPR5) was attributed to the increased availability of nutrients in the soil. As a result, rice plant growth, yield, and essential element uptakes were boosted significantly. The present study’s results suggested using the combined application of AMF + PGPR5 for improving the rice yield and for sustaining the soil health.

Physicochemical characteristics and microbial communities of rhizosphere in complex amendment-assisted soilless revegetation of gold mine tailings

Amendment-assisted soilless revegetation is a promissing ecological restoration method of mine tailings because of its eco-friendliness and low-cost. However, it is difficult to establish the plant community during ecological restoration because of its nutrient deficiency and heavy metal toxicity. In this study, the complex amendment, consisting of 1% peat, 1% sludge and 4% bentonite, was used to assist tall fescue to revegetate gold mine tailings. The variation in physicochemical characteristics and microbial community diversity and composition of rhizosphere tailings were investigated. The complex amendments significantly promoted tall fescue growth with an increase of 35.33% in shoot length and 27.19% in fresh weight. The improved plant growth was attributed to the reduction in heavy metal accumulation and the variation in the characteristics of rhizosphere tailing microecology. The heavy metal concentrations in plant tissues were decreased by 27.71–53.44% in the amended groups. Compared with the control, the available nitrogen (N), phosphorus (P) and potassium (K) levels in TA (without plant cultivation) and TPA (with plant cultivation) were also enhanced by 36.67–49.09% and 42.21–71.47%, respectively. Besides, the amendments introduced more exclusive operational taxonomic units (OTU) and increased the relative abundance of ecologically beneficial microbes in the rhizosphere. Overall, this study provides insight into amendment-assisted soilless revegetation and its effects on microecology to expand ecological restoration of gold mine tailings.

RESIDUAL EFFECTS OF INORGANIC FERTILIZER AND BIOCHAR ON LEAD AND CADMIUM UPTAKE BY Amaranthus cruentus L. ON CONTAMINATED SOIL OF BAGEGA, NIGERIA

The need to remediate contaminated mine soils has led to the adoption of biochar technology. Soils obtained from gold mining sites are heavily contaminated soils due to the presence of heavy metal occlusions in the gold ores. Therefore, a two-trial study was conducted to assess heavy metal uptake by Amaranthus cruentus from biochar amended contaminated mine soils. The experiment was factorial and laid out in a completely randomized design with biochar at seven levels (control; woodchar and bonechar at three rates each) and mineral fertilizer (15-15-15 NPK) at three rates to give rise to twenty-one biochar and fertilizer treatment combinations with three replications. Harvested plant tissues were subjected to wet digestion to determine the concentrations of Pb and Cd. Determined Pb concentrations (0.82-1.04 and 0.74-1.15 mg kg-1) in plant tissues were under the critical limit of 2.0 mg kg-1 set by WHO. Cadmium concentrations (0.38-0.49 and 0.32-0.50 mg kg-1) in plant tissues obtained from both trials were above the critical limit of 0.02 mg kg-1 set by WHO. Values of Pb uptake by plants ranged from 1.99-12.64 mg kg-1 and 0.05-0.71 mg kg-1 in both cropping trials, while Cd uptake ranged from 0.09-0.37 and 0.002- 0.016 mg kg-1. Uptake values of Pb and Cd obtained from the first trial were comparatively higher than values obtained from the second trial. A combination of 30 t ha-1bonechar and 80 kg 15-15-15 NPK enhanced Pb and Cd uptake in both trials while 30 t ha-1 woodchar suppressed heavy metal uptake. Biochar made from plant sources is more suitable for remediating heavy metal contaminated soils.