امیر فتوت

With the approach of attention to the environment, the use of natural materials can be effective in reducing the harmful effects of chemical fertilizers and artificial growth regulators. Drought stress is one of the main limitations of food production around the world, and due to increasing population and water deficiency, there is a global attention for using some materials to increase resistant of plant to drought stress. Chemical stimulants are currently used for decreasing negative effects of water stress in plant. Now a days, use of natural materials, such as plant extract is recommended by researchers. Garlic extract is one of the natural extracts that contains many enzymes and more than 200 biochemical compounds that, due to its richness in minerals and plant hormones, causes cell enlargement, cell division and, plant growth. Humic acid is created from the decomposition of organic matter and is beneficial to plant growth and development. Therefore, the aims of this research were to study the effects of using natural substances of humic acid and garlic extract on nutrients uptake (NPK) and growth of wheat plant under drought stress.

This study was performed during 2018 in a completely randomized design with factorial arrangement in three replications under greenhouse conditions. The studied soil with texture class of loam had pH = 8.11 and EC = 1.28 dS m-1. Experimental factors include drought stress at three levels of 95%, 65% and 45% of field capacity, garlic extract at three levels of foliar application of 0, 2% and 4% and humic acid at two levels of foliar application of 0 and 300 mg l-1. Drought stress were treated by the weight method, 17 days after sowing. Foliar application of humic acid (twice, 13 and 20 days after threating the drought stress) and garlic extract (three times, 18, 24 and 27 days after threating the drought stress) were performed by spraying 150 ml pot-1 of the solutions in each time. The plants were harvested 54 days after sowing and the parameters of shoot dry weight and uptake of nitrogen, phosphorus and potassium in plant were measured. Statistical analysis was done using SAS 9.4 software and the comparison of means was done using Tukey's test at the 5% probability level.

The results showed that foliar application of humic acid and garlic extract alone had a positive effect on dry weight and uptake of nitrogen and phosphorus of shoot. In addition, garlic extract also increased the potassium uptake. Drought stress reduced all investigated parameters; however, foliar application of garlic extract under drought stress conditions increased the absorption of nitrogen, phosphorus, and potassium. In 65% of field capacity, nitrogen uptake by using 2% garlic extract and phosphorus and potassium uptake by using 4% garlic extract had a maximum amount compared to others. In general, garlic extract, due to its antioxidant properties and the presence of growth-promoting compounds such as minerals, vitamins, phytohormones, sulfur compounds, enzymes and amino acids, can improve growth parameters and absorption of nutrients in wheat plant. Humic acid improved growth parameters due to its role in increasing cell membrane permeability, respiration and photosynthesis, phosphate absorption, root and cell expansion, and acting as hormone-like substances.

The foliar application of wheat plant with garlic extract and humic acid as natural stimulants had a favorable effect on the plant growth and nutrients uptake. Garlic extract was more effective than humic acid in reducing the negative effects of drought stress. Finally, the use of natural materials such as garlic extract and some high consumption compounds such as humic acid can be an environment-friendly and safe approach to improve plant growth and to reduce the destructive effects of chemical fertilizers and synthetic growth regulators.

With the progressive increase in industrial and agricultural activities leading to increase in pollutants, soil has received attention as an environmental component and recipient of many of these contaminants.Due to the direct relationship among soil, plants, and humans, pollution in one area may strongly have a negative impact on another.Heavy metals are considered as one type of soil pollutants that can enter the food chain in several ways.Cadmium (Cd) is a heavy metal that has particular importance among the others because it is easily absorbed by plants and causes toxicity.Its detrimental effects on the plant are higher than the other heavy metals.It is crucial to study the uptake and transfer of Cd in the cultivars of wheat which accumulate less amount of Cd.This study aimed to compare the susceptibility of different bread (Triticum aestivum) and durum (Triticum turgidum L.var.durum) wheat cultivars to absorb Cd in Cd-spiked soil.This study was conducted to investigate the effect of different levels of soil Cd (0 and 10 mg kg-1) on its concentration in the roots and shoots of four cultivars (Sirvan, Rakhshan, Talaei, and Parsi) of spring bread wheat and five cultivars (Behrang, Hana, Aran, Shabrang, and Sana) of spring durum wheat.The experiment was set up in a completely randomized factorial design with three replications as a pot experiment in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad.After harvesting, to determine the soil total concentration of Cd was used Aqua Regia method.The amount of cadmium in plant organs was also measured by the wet digestion method (nitric acid and hydrogen peroxide).The translocation and biological accumulation factor were calculated for cultivars of both species.Based on the results, the application of different levels of soil Cd had statistically significant increasing effect on the concentration of this element in roots and shoots of the study wheat cultivars (P<0.01).The Cd concentration in root was estimated more than shoot Cd levels in both wheat species.Among bread wheat cultivars, the most and lowest shoot Cd content was observed in Sirvan and Rakhshan, respectively.On the other hand, in Rakhshan and Talaei were calculated the most and lowest root Cd content, respectively.According to the Cd levels in aerial organs, translocation, and biological accumulation factor, Sirvan had high ability to accumulate cadmium and Rakhshan was more efficient in absorbing cadmium than other cultivars and stored and transported the least amount of this element.Furthermore, according to the information obtained, among durum wheat cultivars, Sana tended to have the lowest Cd concentration of shoot and Behrang tended to have the highest content.In contrast, the highest and lowest amount of Cd in root was related to Sana and Hana, respectively.According to translocation and biological accumulation factor, Sana had less ability to accumulate Cd rather than durum cultivars and Behrang had the highest amount of translocation factors and absorption of this element. Parsi from bread species and Shabrang from durum species had the highest dry weight of shoot in both Cd0 (Control sample) and Cd10 (10 mg kg-1) treatments.In general, bread wheat accumulated a higher amount of Cd in root and shoot than durum wheat.In general, the concentration of Cd in the shoots and roots of both bread and durum wheat species, as well as different their cultivars, was influenced by Cd-spiked soil.Transfer of cadmium from soil and root to aerial organs was an effective factor in the accumulation of this element in plants.According to the results, each wheat cultivar had different abilities to absorb and translocate Cd.Moreover, for the identification of permissible exposure limits of Cd in soil and wheat, some standards should be considered.

 Organic fertilizer tea is a treated solution of organic fertilizers that contains a variety of organic compounds, nutrients and a wide range of microorganisms and their metabolites. In recent years production and use of organic tea as a liquid biological fertilizer or biological pesticides is expanding towards sustainable agriculture. There are many benefits to using tea compost, including providing the nutrients for plant which can reduce the use of chemical fertilizers. A variety of organic compounds can be used to make tea. In the preparation of aerobic organic tea, except for the type of organic matter, preparation conditions such as particle size, temperature, aeration time and fertilizer to water ratio can affect the chemical and biological properties of the produced tea (Shaban et al., 2015). In this regard, the present study was conducted to investigate the effect of aeration time and fertilizer to water ratio on some chemical properties of cow manure and vermicompost tea.

 An experiment was conducted based on completely randomized design with factorial arrangement and three replications. The treatments included aeration time (0, 24, 48 and 72 hours), fertilizer to water ratio (1:10, 1:25 and 1:50) and type of organic fertilizer (vermicompost and cow manure). The part passed through a 2 mm sieve and the rest on a 0.5 mm sieve of air-dried cow manure and vermicompost were used to determination of some chemical properties of organic fertilizers and making tea. After preparing the ratios with distilled water, an air pump was used for aeration. Changes in acidity (pH), electrical conductivity, dissolved organic carbon, mineral forms of nitrogen, dissolved phosphorus and potassium in organic fertilizers tea (cow manure and vermicompost) were evaluated.

 The characteristics of the studied organic fertilizers showed that the total amount of nitrogen, phosphorus and potassium in vermicompost was higher than cow manure. According to the results of analysis of variance, among the main effects, the effect of organic matter type on soluble organic carbon, nitrate and the effect of ratio on nitrate were not significant. The interaction of organic matter type and time on electrical conductivity and the interaction effect of organic matter type and ratio on dissolved organic carbon was not significant. The effect of two-factor interactions on nitrate was not significant. Among the three-factor interactions, the effect of organic matter type, time and ratio on electrical conductivity, acidity (pH), organic carbon and nitrate was not significant. The results showed that aeration decreased the pH and increased the electrical conductivity in both cow manure and vermicompost tea. Despite the higher total amount of nitrogen, phosphorus and potassium in vermicompost, cow manure tea contained higher amounts of soluble ammonium, phosphorus and potassiumcompared to vermicompost tea. The chemical structure of organic matter and the distribution of element in different organic and inorganic fractions can be effective on the dissolution of the mineral part and the biological decomposition of organic part. Changes in the ratio and aeration time had no significant effect on the amount of ammonium and soluble phosphorus in vermicompost tea. In cow manure tea the highest percentage of increase in soluble phosphorus and potassium was obtained by increasing the aeration time up to 72 hours compared to the zero time (without aeration) in a ratio of 1:50. In general, organic carbon decreased as a result of aeration, and only at a ratio of 1:10, this reduction was not significant at 48 and 72 hours. The only factor affecting the amount of nitrate was the aeration time and compared to zero time the amount of nitrate decreased at 24 and 48 hours and increased at 72 hours.

 The results showed that the effect of aeration time and fertilizer to water ratio on nutrient concentrations in teas made from cow manure and vermicompost was different. Despite the higher total concentration of nutrients in vermicompost, the vermicompost tea contained lower amounts of nutrients compared to cow manure tea. In other words, the total amount of nutrients in organic fertilizer cannot determine their amount in the produced tea.

Improper use of ammonium fertilizer could cause this type of pollutant to enter the aquatic ecosystem and enriches water resources. In this research, ammonium adsorption by green synthesized iron oxide nanoparticles with Eucalyptus globulus (EL-Fe NPs) as innovative, inexpensive, and eco-friendly method, was investigated. Characterization of nanoparticles was determined by transmission electron microscopy (TEM), X-Ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The effect of time (0-120), pH (3-11), and KCl salt as ionic strengths on ammonium adsorption by EL-Fe NPS was investigated. Also, kinetics models were fitted with ammonium adsorption data. The results showed iron oxide nanoparticles encapsulated by polyphenols from Eucalyptus globulus extract and have an irregular nanoparticulate structure with a size range between 50-100 nanometers. Ammonium adsorption by EL-Fe NPS was equilibrated at pH≈3.7 after 30 min and 11/86% ammonium was removed from 10 mg/L of initial concentration. Based on the results, this reaction is affected by pH and ionic strength (KCl). By increasing pH, Ammonium removal increased and at pH=7.8 maximum amount of pollutant (76.9%) was removed. Moreover, ionic strength had a contrary effect on ammonium adsorption. In the ionic strengths 0, 0.001, 0.01, and 0.1 ammonium adsorption 76.9, 64.2, 28.2, and 5% was decreased, respectively. These results depict ammonium and potassium compete for adsorption sites of EL-Fe NPs. The pseudo-second-order kinetic model provided a good description for ammonium adsorption (r2=0.998). Considering the effect of increasing the ionic strength in reducing the absorption rate and also the dependence of ammonium absorption on pH, it is expected that the reaction between ammonium and EL-Feb NPs is most likely through electrostatics. In general, it seems that Ammonium adsorption by EL-Fe NPs is influenced by solution chemistry.

Integrating nature into the buildings through green roofs and walls is considered a sustainable strategy in current city development. However, studies on organic waste growing media that allow appropriate plant establishment in these systems are insignificant and yet challenging. This study aimed to evaluate the stability of the Frankenia thymifolia cover plant in four combinations of growing media (30% cocopeat + 65% perlite + 5% vermicompost, 30% leaf litter + 65% perlite + 5% vermicompost, 30% mushroom compost + 65% perlite + 5% vermicompost, and the typical soil used in the green spaces as the control) in the external green wall conditions. The study was a split-plot arrangement in a randomized complete block design with three replications. The main factor was the different seasons in four levels, and the second was the growing media in four levels. Also, at the end of the study, the characteristics of the substrates were tested as a randomized complete block design experiment with three replications. The morpho-physiological traits of the Frankenia plant and the physicochemical characteristics under different growing media were significantly different (p≤0.01). The results showed that leaf surface features, leaf water content, chlorophyll a, b and total, carotenoid, and all the root-related traits were higher in the plants grown in the organic matter growing medium than those grown in the typical soil. Also, better physicochemical attributes (lower bulk density, porosity, less ash, more air volume, and more acidity) were observed in organic growing medium in comparison with the typical soil. The results of this research confirmed the favorable effect of using washed mushroom compost along with perlite and vermicompost instead of the common imported green wall substrates. It also suggests using the Frankenia in climates similar to Mashhad year-round in the external green wall systems.

Boron (B) has a dual effect on living systems, so that the concentration range within which B is changed from a nutrient to a pollutant is rather narrow. Although B plays essential roles in all living organisms, its long-term excessive uptake has adverse effects on either human beings or plants and animals. Furthermore, part of the B that can be used as fertilizer is highly soluble and easily leached into the soil profile leadsing to some problems such as decrease of fertilizer efficiency. Therefore, to improve agricultural productivity through its gradual uptake by plants, the increase of B adsorption in the soil solution is necessary. Many adsorbents have been used for the adsorption of B from aqueous solutions; however, layered double hydroxides (LDHs) have been considered as one of the most effective adsorbents as well as slow releaser fertilizers of inorganic anions such as nitrate, phosphate, etc. The formula of LDHs are typically denoted as [M1-x 2+M x 3+ (OH)2]x+ (An-) x/n .m(H2O), where M2+ and M3+ are divalent and trivalent cations, respectively, the significance of x is the molar ratio of M3+/(M3++ M2+) and An- is the intercalated anion. Although LDH materials are commonly prepared by combining two divalent and trivalent metals, more metals can be introduced in the brucite layer to achieve a large variety of composition and higher adsorption capacity. Stability of LDHs in soil can be affected by numerous factors (e.g. low molecular weight organic acids (LMWOAs)) leading to release of structural cations in addition to interlayer anion. However, there are scarce investigations that have evaluated the potential of ternary LDHs (e.g. Zn–Mn–Al LDH) in desorption of B (as interlayer anion) and release of Zn and Mn (as structural anions) in a simulated soil solution. Therefore, the objectives of this study were, i) to compare the desorption of B capacity of binary LDH (Zn–Al LDH) and ternary LDH (Zn–Mn–Al LDH) in the simulated soil solution, and ii) to investigate the effect of three different electrolytes (potassium nitrate, oxalic acid, and citric acid) on the release of Zn and Mn from synthesized LDHs.
 A modified urea hydrolysis method was employed to synthesize Zn–Al and Mn-substituted Zn–Al LDHs with Zn(+Mn)/Al molar ratio of 2. Herein the contents of Mn with respect to Zn corresponded to 2% and 10% molar ratio. Accordingly, the synthesized materials denoted as Zn–Al, Zn–Mn1 and Zn–Mn2 for the samples without Mn, with 2 and 10 mol% Mn with respect to Zn content. For investigation of B desorption at a concentration of 10 mM, 15 mL from equilibrium solutions were substituted with 15 mL of 0.03 M KNO3 and shaken for 240 min. Substitution was repeated four times and A modified urea hydrolysis method was employed to synthesize Zn–Al and Mn-substituted Zn–Al LDHs with Zn (+Mn)/Al molar ratio of 2. Herein the contents of Mn with respect to Zn corresponded to 2% and 10% molar ratio. Accordingly, the synthesized materials denoted as Zn–Al, Zn–Mn1 and Zn–Mn2 for the samples without Mn, with 2 and 10 mol% Mn with respect to Zn content. For investiigatigatingon of B desorption at a concentration of 10 mM, 15 mL from equilibrium solutions were substituted with 15 mL of 0.03 M KNO3 and shaken for 240 min. Substitution was repeated four times and B concentrations in extracts were measured by Azomethine-H method. Furthermore, the supernatant Zn and Mn concentrations were determined by GF-AAS (PG 900). This process was repeated for 1.25 mM oxalic acid and 1.25 mM citric acid to study the effect of these compounds on B desorption as well as release of Zn and Mn. B concentrations in extracts were measured by Azomethine-H method. Furthermore, the supernatant Zn and Mn concentrations were determined by GF-AAS (PG 900). This process was repeated for 1.25 mM oxalic acid and 1.25 mM citric acid to study the effect of these compounds on B desorption as well as release of Zn and Mn.
The adsorption and desorption isotherm were carried out to describe the distribution of B between the liquid and adsorbent. The isotherm data of synthesized LDHs were matched with Freundlich model. The values of 1/n in this model were found between 0 and 1 for all LDHs indicating favorable sorption of B on these compounds. The highest adsorption was observed for ternary LDHs (particularly Zn–Mn2) due to their higher specific surface area and also due to the ion exchange mechanism in combination with surface adsorption. However, the results showed that the percentages of B desorption by potassium nitrate, oxalic acid and citric acid were lower for Zn–Mn1 (19.4, 29.1 and 38.2%, respectively) and Zn–Mn2 (18.6, 28.2 and 35.9 %, respectively) than Zn–Al (30.8, 41.2 and 46.2%, respectively). This observation suggests that the type of LDH, B adsorption mechanism and background electrolyte can affect the amount of B desorption. Furthermore, after 4 successive desorption cycles, the concentration of Zn and Mn increased in the supernatants (particularly in organic acid electrolytes) suggesting dissolution mechanism possibility happened for the studied LDHs. Among the background electrolytes, citric acid was the most effective compound in releasing Zn and Mn, followed by oxalic acid and potassium nitrate. A reason for this such observations could be that with respect to chemical structure, citric acid by three carboxyl groups can form more chelate rings compared to oxalic acid, which contain two carboxyl groups. Therefore, it seems that B containing Zn–Mn–Al LDH may have potential to be used as a slow release fertilizer in soils to supply three essential elements, including B, Zn and Mn simultaneously. However, further studies are required to support such a hypothesis.

Boron deficiency is an important disorder that can affect plant growth in calcareous soils. Various plants have different mechanisms of uptake. To investigate the different strategies of plants in increasing the efficiency of boron uptake, a factorial experiment was conducted in a completely randomized design with three replications in the greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The experiment was conducted with three levels of boron (B0, B1.5, and B3 kg/ha) in the form of boric acid and three plant species (spinach, lettuce, and leaf beet). The results revealed that addition of boron enhanced shoot dry matter content in all plants. Lettuce shoot biomass was increased by 32% at B3, indicating that lettuce had a greater growth response to boron levels. Differences in boron concentrations in spinach (61.8 mg kg-1) and leaf beets (71.4 mg kg-1) compared to lettuce (31 mg kg-1) at the B0 level showed the importance of root characteristics and other factors affecting boron solubility and uptake efficiency such as root exudates. The concentration and uptake of boron in spinach were more affected by boron levels compared to lettuce and leaf beet. In spinach, the shoot and root boron concentration increased by 44% and 30%, respectively, and uptake in shoot and root also increased by 53% and 37%, respectively, at B3, compared to the control. Generally, different efficiencies of these plants in boron uptake were due to the high boron influx into spinach and leaf beet and low influx into lettuce.

Heavy metals pollution is one of the major environmental concerns in the world, as these metals are a threat to humans, animals, and plants due to their toxicity. Clay minerals which are a major component of the soil, play an important role in the absorption of various contaminants in soil and water. Bentonite (B) and its modified forms have a much higher capacity to adsorb toxic metals than other clays. This experiment was accomplished in a completely randomized design in a factorial arrangement with three replications. The experimental treatments consisted: time (5, 10, 20, 30, 60, 120, 240 min), B and nanobentonite (NB) adsorbents (2 g l-1) and humic acid concentrations (0, 100 and 500 mg l-1). The results showed that humic acid increased Cd adsorption by B and NB in different times. The highest amount of Cd adsorption by B adsorbent was 4370 mg kg-1 recorded in 500 m l-1 humic acid treatment and the lowest amount of adsorption was observed in the absence of humic acid 1134 mg.kg-1 by bentonite adsorbent. Semi second-order kinetic model was significantly fitted to Cd adsorption by B and NB in all of the humic acid concentrations (R2 for all three levels of humic acid in bentonite adsorbent and treatment of 100 mg.l-1 humic acid in nano bentonite adsorbent was 0.99,  for treatment of zero and 500 mg l-1 humic acid was 0.97 and 1.00, respectively). The results of current study showed that humic acid could markedly promote the Cd adsorption by adsorbents, which had a greater effect on the adsorption of B than NB.

The use of silicon has been considered as an effective strategy in reduce of cd uptake and affecting the oxidative damage caused by cd toxicity. The aim of this study was to investigate the effect of the presence silicon (0.1 mM/L) and different levels of cadmium (0.10, 50 μmol/L) in wheat plants under hydroponic conditions. The results showed that increasing the concentration of cd increased the concentration of malondialdehyde (MDA) significantly and reduced MDA compared to plants treated only with cd. The results also showed that cd stress caused significant decrease in superoxide dismotase (SOD), polyphenoloxidase. (POD), and Catalase (CAT) activity in wheat leaves and roots. The results showed that the use of silicon significantly increased the activity of SOD, POD, APX enzymes in both leaves and roots, while it had no effect on CAT activity in leaves, but significantly increased catalase in roots. The results demonstrated that the use of silicon in cd stress conditions improves the damage caused by oxidative stress in the plant.

Currently, the idea of ​​integrating nature and buildings through green roofs and green walls has been considered as a sustainable strategy in cities. However, studies on the substrates which allow the plants to fully establish in these systems are still lacking. It is also a challenge to find the substrates which provide the plants with proper growth, nutrition, and environmental sustainability. This study aimed to evaluate the performance of Frankenia thymifolia in four types of growing media (30% cocopit + 65% perlite + 5% vermicompost, 30% soil + 65% perlite + 5% vermicompost, 30% mushroom compost + 65% perlite + 5% vermicompost and common soil used in the green spaces as the control) in growing conditions of the external green walls. The experiment was conducted as a split-plot in a randomized complete block design with three replications. The main factor was different seasons of the year in four levels and the second factor was the substrates in four levels. The effect of different substrates on thermo-dynamic factors of the substrates and on morphological, qualitative, and water use efficiency characteristics of the plants were significant at the 5% probability level. The results showed that the temperature and humidity of the substrates containing organic compounds were higher than those of the soil. Also, plant height, number of nodes, percentage of coverage, and water use efficiency of the plants were higher in the growing medium containing mushroom compost. Having a high water use efficiency and keeping its qualitative characteristics to an acceptable level in the summer and spring, Frankenia was found to be a suitable species in these seasons. However, due to the cold-induced deleterious effects in winter on these characteristics, it was not a suitable plant species for external green wall systems in climatic conditions of the winter season of Mashhad. Based on this studychr('39')s results, we suggest adding washed mushroom compost to the usual green wall substrate. Frankenia can also be considered a suitable plant for external green walls in spring, summer, and autumn in similar weather conditions to Mashhad.

Boron is one of the micronutrient elements needed by plants. High concentrations of this element in agricultural waters, especially in arid and semi-arid regions, cause toxicity in plants grown in these areas. various methods have been proposed to reduce the concentration of boron in water and soil that surface adsorption is one of the most important. in recent years, the use of layered double hydroxides (LDHs) or hydrotalcite (HT)-like, compounds as anionic adsorbents from aqueous solutions has been taken into special consideration. One of the most important reasons for the use of attractions is affordability. Now, if, in addition to high adsorption efficiency, they can be reused, can be used on a large scale. Therefore, in view of these points, in addition to measuring the adsorption capacity of LDH types, the desorption quality was also evaluated, because it plays a significant role in its reusability.

in this research, two types of layered double hydroxides (LDHs) with different kinds of metal ions (Mg-Al and Mg-Fe) were prepared by co-precipitation method in nanometer dimensions, and their adsorption features were evaluated in vitro to remove boron from aqueous solution. The Hydrotalcite-like features were determined by chemical analysis, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and Energy-dispersive X-ray spectroscopy (EDS). The affinity of these materials for adsorption of different species of boron in solution was studied as a function of pH, contact time, LDHs quantity and B concentration (Langmuir and Freundlich adsorption isotherms).

Boron removal was independent of the solutions' initial and final pH because of the high buffering capacity of the LDHs. the highest amount of boron was adsorbed on Mg-Al-LDH and Zn-Al-LDH, at the first 10 and 20 minutes, respectively. It was found that 80 min is enough time for the equilibrium state to be reached in boron adsorption for two types of LDHs. Boron adsorption capacity increasing the adsorbent quantity (0.5-5 gr/lit) and application of 5 gr/lit of Mg-Al-LDH and Zn-Al-LDH absorbed 52% and 60% of the initial boron amount, respectively. The adsorption isotherms, described by the Langmuir model, are of L-Type isotherm, suggesting that B(OH)4- is adsorbed preferentially on HT-like materials. Zn-Al-LDH with the maximum adsorption capacity of 3 mg/gr had a higher adsorption capacity for boron than Mg-Al-LDH (with the highest adsorption of 2.48 mg/gr). On the other hand, the desorption of boron from Zn-Al-LDH by 200 mg sodium nitrate solution per lit, was higher than that of Mg-Al-LDH.

After the treatment of a solution containing 2 mg of boron per liter using 0.5 gr of both adsorbents, the final boron concentration reduces to below the recommended limit by WHO for drinking water (0.5 mgL-1). Both types of LDH are highly capable of removing the boron element from contaminated solutions; but with the aim of reusing the adsorbent and, consequently, its "cost-effectiveness", Zn-Al-LDH nano-adsorbent could be more proper to use than Mg-Al-LDH nano-adsorbent, due to higher adsorption and desorption.

Lead as a heavy metal and permanent chemical contaminant threat the health of environment and alive creatures through different artificial and natural sources. In order to investigate the effect of methyl jasmonate and lead stress on growth characteristics, the adsorption and accumulation of lead and hazardous index in basil, a pot factorial experiment was carried out based on completely randomized design in research greenhouse of Ferdowsi University of Mashhad. The treatments consisted of three levels of lead nitrate (0, 200 and 400 mg/kg soil), and methyl jasmonate spraying in three concentrations (0, 0.5 and 1 mM). The mean comparison of data represented the reduction in all the studied morphological traits and increasing the amount of lead in the leave and root of the plant and hazardous index with increasing lead stress levels and spraying with methyl jasmonate could partly improve some of these traits. So that spraying with 1 mM methyl jasmonate cause to increase 6.01% inflorescence length and cause to decrease lead amount of the eave 96.56, 79.31 and 99.20%, respectively and hazardous index, however, at o.5 mM methyl jasmonate cause to increase the number of branches and aerial fresh weight, 27.66 and 9.84%, respectively. Therefore, it seems that application of methyl jasmnate on stress conditions could improve partly the traits and so in some cases 1 mM methyl jasmonate concentration cause to decrease some morphological traits. Therefore, application of o.5 mM methyl jasmonate on lead stress is recommendable.

Sugarcane cultivation has been revived in Khuzestan province of Iran since the 1960s and  due to good results, gradually began to grow from north to south of this region. Currently, sugarcane is cultivated in more than 100,000 hectares of the province's land and almost 25% of the country’s demand for sugar is produced in this region. Regarding the very low rainfall and water resources reduction of the country in recent years, the optimal use of irrigation water is very important. Sugarcane fields in Iran due to irrigation problems such as distribution and consumption management, and the lack of continuous and uniform water supply, have high water use per hectare. In other words, the irrigation water use of farms is twice to three times of the real water need of sugarcane. Irrigation water use efficiency or WUE, which can be calculated from the ratio of plant dry matter to water consumption per hectare (Anyia and Herzog, 2004), is a very important criterion that can be of use in evaluating and improving irrigation operations and optimal water consumption. The water use efficiency of sugarcane depends on various factors such as climate, soil characteristics, irrigation management, cane cultivar and plant growth stage.Irrigation water quality, climate change, weeds and soil characteristics (high pH and low organic matter, for example) are the main factors that affect production of sugarcane in Iran. Therefore, the yield of the sugarcane is also far from the potential yield. Sugarcane fields of Khuzestan province are mainly rich in lime percentage and poor in organic matter and phosphorus. Soil pH in this region of the country is also about 8-8.5 and uptake of some elements such as phosphorus, by plants and phosphorus fertilizer efficiency in these soils (alkaline and calcareous soils) are expected to be low (Wang and Wang, 1995). The optimum use of phosphorus fertilizer and water irrigation are essential for the quantitative and qualitative function of sugarcane plants. Due to the very low mobility of phosphorus in soil, its uptake by plants such as sugarcane is affected by the number of soil and plant factors (especially plant root characteristics). Changes in these factors can lead to reduction or increase of P uptake by the crop.Because of the role of organic compounds in improvement of mobility and phosphorus uptake, the use of organic maters has been considered in several researches. Organic compounds can play a direct and indirect role in plant factors and in phosphorous uptake improvement, yield increase and finally water use efficiency improvement.

According to the population growth and increasing production of urban waste, environmental hazards of these wastes are on of the most important challenges in most cities that the safest way to prevent them from accumulating is to add them to the agriculture lands. This case is especially considered in countries with dry climates because of lacking organic matter in soils. Due to the high consumption of vegetables in the country and the use of sewage sludge as soil fertilizer, the risk of soil pollution for the peresence of heavy metals in soil and plant may threaten human and creature health. Consequently, studies need to be conducted to evaluate the effect of different levels of sewage sludge on of zinc (Zn), cupper (Cu), cadmium (Cd) and lead (Pb) concentration in root and shoot of radish (Raphanus sativus) and and basil (Ocimum basilicum) vegetables.

This study aims to investigate the effect of domestic sewage sludge on concentration of zinc (Zn), cupper (Cu), cadmium (Cd) and lead (Pb) in radish (Raphanus sativus) and and basil (Ocimum basilicum) vegetables. A pot experiment in greenhouse was conducted at Ferdowsi University of Mashhad, Faculty of Agriculture, in 2018. The experiment was performed in a completely randomized design with three replications. Sewage sludge was consumed at five levels (0, 10, 20, 40, 80 t ha-1) during plant growth. Available form of heavy metals in soil samples was extracted by DTPA 0.005 M solution. total concentration of heavy metals in sewage sludge and soil measured by Aqua regia method and concentration of plant metals measured by dry digestion method.

The results indicated that the use of the sewage sludge in different treatments levels had significant impact (p < 0.05) on the concentration on of these heavy metals in the two plants studied. increase of sewage sludge enhanced metals concentration in shoot and root rather than control plant. particularly for Zn, in root and shoot in both plants. Increase in concentration metals in the two plants were followed Zn> Cu> Pb> Cd in both roots and shoots, The metals uptake in radish was drastically higher than basil. the value of all the metals at 10 t sludge per ha were lower than permissible concentration and at 80 t per ha were higher than permissible concentratoin for all of them.

in general, application of different levels of sewage sludge in soil caused changes in soil chemical properties including decrease of soil pH, increase of electrical conductivity, and soil organic carbon. Also, in the treatment of last level of sewage sludge, two plants were toxic and in the lowest level of treatment of sewge sludge, no toxicity and damage were observed in the plants. However, continuously application of the sludge at 10 t per ha did not plluted the plants, should be recommended cautiously As the results of the study indicate, application of the lowest level of sewage sludge should also be performed with constant precision and monitoring.

Soil contamination is one of the most important pollutants in the environment. Lead (Pb) is one of the heavy metals and important pollutant in arid ecosystem. The use of plants to remove contaminated soil or Phytoremediation is an economical method. Todays due to increasing the pullution of soil sources and resultant problems, identification the resistant plant species against soil pollution is essential. Effeciency of Vetiver and Brassica to Pb uptake has not studied and compared, therefore, this study was carried out in order to compare the Phytoremediation capacity of Pb by two plants i.e. Vetiveria zizanioides and Brassica oleraceae, and to indentify the better specie for this purpose.

A completely randomized design with factorial arrangement in greenhouse conditions was carried out. Treatments included two types of plants (Vetiveria zizanioides and Brassica oleraceae) and three rates of Pb contamination in soil (50, 250 and 500 mg / kg prepared from lead nitrate) in three replicates. After measuring the amount of Pb in soil by DTPA, the concentration of Pb in root and shoot of plants, Translocation factor (translocation from roots to shoots) and Bio-accumulation factor (translocation from soil to roots) were measured, too. Data analysis was performed using JMP software and comparison of means by LSD method.

The results of analysis of variance showed that the effect of plant type, soil contamination rates and their interaction on accumulation content of lead in root and soil were Significant at p < 0.01, while the effect of soil contamination rate on the shoots of plant was Significant at p < 0.05. The highest accumulation contents of lead in roots and shoots were found in Vetiver plant containing 250 mg / kg of soil pollution rate treatment. Also, the highest amount of Pb accumulation in soil was related to Brassica containing 500 mg/kg of soil treatment. Vetiver in root and shoots accumulated Pb 3.5 and 2.1 times more than Brassica, respectively. In addition, the accumulation content of Pb in the roots of Vetiver was 4 times higher than its shoots, while the concentration of Pb in roots of Brassica was 1.5 times greater than its shoots. Translocation factor in both plant was less than 1, while bio-accumulation factor of Vetiver was greater than that of Brassica in all Pollution rates.

Despite the ability of both plants to accumulate lead in their roots and shoots, Vetiver had the better performance in lead uptake from soil and reduced lead amount in soil, so its application is recommended for Phytoremediation purposes.

The present study was designed to investigate the effect of Nano hydroxyapatite (nHAP) on some soil bioindicators and availability of cadmium in a polluted calcareous soil. This research was carried out in a factorial arrangement based on completely randomized design with three replications. Treatments included two levels of Cd (0 and 40 mg kg-1 soil), two levels of nHAP (0 and 1%) and two incubation times (14 and 28 days). The cadmium chloride solution was uniformly sprayed on the soil surface and equilibrated for a month, then nHAP was added to the soil at 0 and 1 w/w %. The activity of urease, dehydrogenase, and alkaline phosphatase enzymes, basal respiration and bioavilable Cd were measured after 14 and 28 days. Bioavilable Cd was extracted by DTPA. The results showed that the addition of nHAP in the Cd contaminated soil decreased bioavailable Cd by 2.3%, increased the activity of urease enzyme by 98% while had no effect on the activity of phosphatase, dehydrogenase and basal respiration. Investigation of changes of bioindicators in 14 and 28 days incubation in Cd contaminated soil showed that the activity of urease and dehydrogenase enzyme had a declining trend but the activity of phosphatase enzyme and basal respiration did not significantly change. It was also found that bioavailable Cd decreased with incubation time by 10.7%. In general, it may be concluded that nHAP influenced biological index in the calcareous soil differently, but it caused reduction effect on bioavailable cadmium in soil, although this reduction was not considerable.

Acenaphthene, a natural component of crude oil, is a carcinogenic compound and persistent to degradation. Bioremediation, which involves the use of living microorganisms for degradation and mineralization of contaminants, used to remove persistent contaminants such as Acenaphthene. Complete degradation of hydrocarbons is the result of different species activity that is known as a bacterial consortium. On the other hand, the low solubility of oil pollutants is a limiting factor in bioremediation. So, recently biosurfactant-producing bacterial consortia have been considered in the bioremediation to increase the bioavailability of oil contaminants. In the present study, Asenaphthene degrading bacteria were isolated by enriching the oil-contaminated soil and then, the biosurfactant-producing bacteria were screened based on the surface tension of the medium containing the isolates. After bacterial identification, degradation of Acenaphthene by isolates, consortium, and extracted biosurfactants from isolates, were investigated in the aqueous medium and soil. The results showed that both AP3 and BM1 could decompose Acenaphthene and produce biosurfactants. The AP3, BM1, and their consortium degraded 72.2%, 54%, and 100% of pollutants in the aqueous medium, respectively. The effect of biosurfactant extracted from AP3 on the degradation of Acenaphthene was more than the BM1 biosurfactant. Percentage of Acenaphthene degradation in soil by AP3 and consortium was 64.7% and 75.7% respectively, and the use of AP3 biosurfactant with the consortium led to complete degradation. 16S rRNA gene sequences of isolates showed that AP3 100% was compatible with Bacillus velezensis CR-502 (T) and BM1 99.5% was compatible with Pseudomonas putida ATCC 12633. Therefore, the use of a consortium and biosurfactants improve the biodegradation of Acenaphthene compared to inoculation of individual isolates.

Microbial biofilms are one of the most important microorganism’s forms of life in the environment. The aim of this study was to use native Pseudomonas aeruginosa in biofilm form to clean up phenanthrene.

Among 63 Pseudomonas isolates from Iranian soil, bacterial isolate with high potency in biofilm formation and crude oil degradation was selected and genetically identified. The effect of inorganic (raw pumice, processed pumice and perlite) and organic (biochar and sugarcanes bagasse) carriers on biofilm formation was investigated. Biofilm structure was studied by scanning electron microscopy. Also, the effects of two growth form (biofilm, planktonic) on biochar carrier on laccase production and phenanthrene degradation in liquid media was investigated.

Purified Pseudomonas isolates were screened based on biofilm formation and crude oil degradation. B59 (Pseudomonas aeruginosa) with 56.62% showed the highest percentage of crude oil degradation. Highest and lowest CFU belonged to biochar and processed pumice with 8.8 and 2.9 respectively. Laccase activity was measured in biofilm form and planktonic form 39.8 and 33.1 Um-1 respectively. Biofilm form of Pseudomonas aeruginosa led to 97.17% phenanthrene degradation where planktonic form reached 91.37%.

Results showed that biofilm form of Pseudomonas aeruginosa compared to planktonic form by significant increase in CFU and laccase activity result in more phenanthrene degradation in liquid media.

Today, the use of biochar in the sustainable management of soil fertility, has been drawing the attention of the scientists as a multi-purpose and environmentally friendly strategic idea. There are several scientific reports implying the outstanding positive effect of biochar on soil fertility and plant growth. On the contrary, some inconsistent reports have mentioned negative or no effect of biochar. Therefore, it is necessary to investigate the effect of any biochar on the soil and plant before any widespread use of any kind. In the present study, the effect of three different biochar and their raw materials on potassium availability and corn growth was studied.

The study was carried out as a two-part-experiment, including laboratory and greenhouse parts. In both parts of the study, treatments included the control (soil without any biochar or its feedstock), Municipal Waste Compost (MWC), Biochar of Municipal Waste Compost (BMWC), Sewage Sludge (SS), Biochar of Sewage Sludge (BSS), Cow Manure (CM), and Biochar of Cow Manure (BCW). In each study, application rates of treatments to the soil, were 1% w/w. In the laboratory part, the effects of the treatments on available-K and parameters of Quantity/Intensity (Q/I) ratio of potassium were investigated. Also the effects of the treatments on plant growth, K-concentration and K-content of corn were investigated in the greenhouse part.

The CM and its biochar, highly increased the available-K by highly increasing the potassium-Q/I parameters compared to the control. While the SS and its biochar lightly increased the available-K by lightly increasing the potassium-Q/I parameters. The CMW and its biochar, intermediately increased the available-K by intermediately increasing the potassium-Q/I parameters compared to the control. Treatments could improve could improve the growth, k-concentration and k-content of corn compared to the control, excepting of MWC in the case of the plant growth, and SS and BSS in the case of k-concentration. Totally, the descending order of treatments in terms of increasing K-availability was as the follows: 1-BCM, 2- CM, 3-BMWC, 4-MWC, 5-SS and BSS, 6-control. The descending order of treatments in improving plant growth conditions and increasing dry weight of the plant was as the follows: 1-CM, 2-BSS and SS, 3- BMWC, 4- BCM, 5- Control and MWC.

Considering the superiority of BMWC to MWC, in terms of affecting on K- availability and plant dry weight, BMWC can be preferred to MWC. Considering the superiority of BCM to CM in terms of the effect on K-availability, K- concentration and content of plant compared to the control, meanwhile its decreasing effect on plant growth compared to CM, it seems that some considerations such as salinity and nutritional balance must be carefully considered and managed in the case of BCM application. Despite the similarity of BSS and SS in terms of increasing plant growth, BSS application can be preferred to SS because of the more value of PBCK, and consequently, the more continuously K-supply.

Due to limitations of laboratory tools and difficulty in interpreting the results obtained from complex porous media such as soil, artificial porous media such as glass beads, pure sand and quartz and riverbed sand are oftenly used to investigate the transfer of nanoparticles in porous media. In this study, the effect of different flow rates on transfer of titanium dioxide nanoparticles was investigated in the undisturbed soil columns. The flow rate equal to 100, 90, 70 and 50% of the saturated hydraulic conductivity were applied on the soil columns by the peristaltic pump (BT100-1F). By measuring the breakthrough curves for each column, the parameters explaining the transfer of nanoparticles based on a one-site sorption model, one-kinetic site sorption model, and a two-kinetic site sorption model were determined. The results indicate by increasing the flow rate, the reltive concentration of TiO2 nanoparticles (C/Co) in the soil column increases from 3% to 28%. Among the three studied models, the two-kinetic site sorption model which consider the physical straining mechanism based on the particle size and porosity of the porous medium, the function of saturation of the porous media particles with nanoparticles and the physical straining function considering changes of this mechanism with distance, shows the best fit (R2>%90) for estimation of the nanoparticles transfer in the soil column.

Soil enzymes are considered as a measure of soil biological status. Phosphatase enzymes (alkaline and acid) are very important because of their role in converting organic to inorganic phosphorus and improving plant nutrition. Various factors such as organic compounds and phosphate fertilizers affect the activity of these enzymes. In this study, the effect of humic acid and phosphorous (P) fertilizers onsoil rhizosphere phosphatase enzymes, active carbon and P uptake by sugarcane was investigated, conducting a greenhouse pot experiment in south west of Iran. The experiment was performed as a factorial based on complete randomized design, in three levels of P application as triple super phosphate (0, 50% and 100 % of recommended phosphorus application, 250 kg.ha-1, in the region), four humic acid treatments (three immersion levels of setts in 0, 0.3 and 0.5% solution of humic acid as well as application of 30 mg humic acid per kg soil treatment) and two harvesting time (45 and 90 days after planting). The results showed that in non-fertilized treatment, the use of humic acid (especially in the form of cuttings immersion) increased P uptake by about twice at the first harvest and by 30% at the second harvest compared to the control treatment. Improvement of P uptake in the soil with deficit P was due to changes in activated carbon in the rhizosphere and also the impact on density and activity of microorganisms and the activity of enzymes such as phosphatase, which increases the availability of P in the vicinity of the plant root. By increasing the phosphorus application, the activity of the alkaline phodphatase enzyme decreased and reached to the minimum measured value dry soil (17% Less than the control).

Sugarcane cultivation has been revived in Khuzestan province of Iran since the 1960s and due to good results, it gradually began to grow from north to south of this region. Currently, sugarcane is cultivated in more than 100,000 hectares of the provinceand almost 25% of the country needs for sugar arebeing produced in this region. Sugarcane fields of Khuzestan province are mainly rich in lime percentage and poor in organic matter and phosphorus. Soil pH in this region of the country also is about 8-8.5 and phosphorus uptake by plants and phosphorus fertilizer efficiency in these soils (alkaline and calcareous soils) are expected to be low. The optimum use of phosphorus fertilizer and proper phosphorus uptake is essential for the quantitative and qualitative function of sugarcane plants. Due to the very low mobility of phosphorus in the soil, its uptake by plants such as sugar cane is affected by number of soil and plant factors (especially plant root characteristics). Changes in these factors can lead to a reduction or increase of P uptake by the crop.

Because of the role of organic compounds in the improvement of mobility and phosphorus uptake, the use of organic material has been considered in many types of research. Organic compounds can play a direct and indirect role in plant factors and in phosphorous uptake improvement. In this regard, a greenhouse pot experiment was conducted in 2016-2017 at Farabi Agro Industry Co, 35 km south of Ahvaz, Iran (48º 36' E, 30º 59' N). This research carried out by using three levels of humic acid (immersion of settes in three concentrations of 0, 0.3 and 0.5% of humic acid) as well as three levels of phosphorus fertilizer (triple super phosphate) 0, 50 % and 100% of the recommended amount in the region (250 kg/ha) in two different harvesting periods (45 and 90 days after planting). The experiment set up as a factorial, based on complete randomized design with three replicates. In this experiment, the effects of different levels of phosphorous fertilizers and humic acid on aerial part (shoot height, shoot dry weight), underground part (root length, root dry weight and root hair length), and also root CEC of sugar cane plant in two harvest times were studied. Finally, uptake and influx of phosphorus in different treatments were investigated.

As the results show, although the range of the changes was different, the use of humic acid could improve almost all of these factors. Shoot height, shoot dry weight in humic acid treatments showed a significant increase in both harvests compared to non-used humic acid treatments and also in phosphorus fertilizer treatments as the fertilizer levels rose. These results show that humic acid can increase the uptake of phosphorus from the soil reservoir (treatments without phosphorus fertilizer) and source of soil and phosphorus fertilizer (phosphorus fertilizer treatments). The underground plant parts have also shown similar results. Root length and root dry weights have also been shown positive results in humic acid treatments. Therefore, an increase in phosphorus uptake in non-use phosphorous fertilizer treatments or phosphorous fertilizer treatments, along with humic acid, relative to non-humic acid treatments could be explained. The humic acid application seems to increase the uptake capacity of phosphorus from soil and fertilizer sources by increasing root length and root dry weight. In addition, the use of humic acid in alkaline soil can increase the solubility of phosphorus in water and therefore the phosphorus uptake by the roots of the plant could be increased. Based on the results, using humic acid due to improved phosphorus fertilizer use efficiency, phosphorous uptake by plant is expected to be increased and hence the fertilizer use would be reduced. Phosphorus influx results had not the same direction with uptake and application of phosphorus fertilizer. P influx results showed an inverse relationship with root length. In other words, phosphorus uptake was more dependent on the root growth.

This study showed that it is possible to use humic acid in the practical form during the cultivating of sugarcane setts, but it seems that further research is needed to examine other important points such as the use of humic acid during plant growth season and other its application forms, such as spraying or application in irrigation water.

Reducing iron solubility in calcareous soils causes iron chlorosis symptoms in the plant. In order to investigate the response of M. scutellata to direct and indirect iron deficiency, a factorial experiment was conducted in a completely randomized design with three replications. The experimental factors included three levels of lime (0, 4 and 8%) and five levels of Fe (0, 5 and 10 mg Fe Kg soil-1 as soil application and 0 and 2.1 µM Fe as foliar spray). Zero Fe concentrations in soil and foliar Fe fertilization was considered as control-S and control-F treatment, respectively. The results showed that the amendment of 8% CaCO3 in control treatments caused typical Fe deficiency symptoms, including decreases in chlorophyll, total and extractable leaf Fe concentration, protein, leaf relative water content, membrane stability index and increases in leaf total phenolic and flavonoid concentration when compared to 0% lime. The soil and foliar Fe fertilisation led to the improvement of Fe chlorosis, increases in chlorophyll, Fe, protein, and decreases in concentration of phenolic compounds in three levels of lime. The foliar Fe fertilization in three levels of lime increased total and extractable leaf Fe content, compared to two soil Fe treatments, but foliar Fe fertilization (in 4 and 8% of lime) yielded progressively lower leaf phenolic compounds. The highest leaf chl concentration in 8% lime was observed in 10 mg Fe Kg soil-1 and foliar Fe fertilization. The presented data indicate that the use of foliar application of Fe (Fe- EDDHA) is potent to reduce the effects of lime induced chlorosis in plants in calcareous soils.

Environmental contamination by crude oil and its various processing products is becoming a common phenomenon which severely damages soil and groundwater resources. Among the constituents of oil waste, polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because of their toxic, mutagenic and/or carcinogenic effects. Bioremediation involves the use of living microorganisms, bacteria or fungi, for detoxification of soil and water organic pollutants by biodegradation, biotransformation, and/or mineralization. Collaboration between different microbes under co-culture conditions such as co-metabolism or antagonism makes the system to perform better than a single microorganism. Total petroleum degradation is a result of a microbial consortium action, which is composed of different species with specific biochemical roles. On the other hand, the majority of components of petroleum products has low solubility in water and tends to bind to soil particles reducing their availability to  microorganisms for degradation. This has been well described as a major limitation to the bioremediation of hydrocarbon contamination. The surfactants can be employed to enhance hydrocarbon biodegradation by mobilization, solubilization, or emulsification. Some microorganisms synthesize a wide range of surface-active compounds, generally called biosurfactants, which increases the bioavailability of these compounds. The application of these microbial surfactants in the remediation of hydrocarbons aims to increase their bioavailability or mobilize and remove the contaminants by pseudo-solubilization and emulsification in a treatment process. This work aimed to investigate the impact of the biosurfactant producing consortium on the benzo(a)pyrene biodegradation.

Four gasoline contaminated soils were enriched in Bushnell-Hass mineral medium with Benzo(a)pyrene (200 mg/l) for three months at 30°C. After this time, to obtain Benzo(a)pyrene-degrading isolates, 0.1 ml of soil suspensions were plated on BH agar plates containing pollutant. Three colonies with different morphological distinct properties were purified on LB agar plates. The screening of the most potent surfactant strain was assayed quantitatively using measurement of surface tension by the Du Nouy ring method. For increasing the production of biosurfactant, medium conditions including pH (6, 7, 8), temperature (25, 30, 35) and carbon source (glucose, sucrose and ribose) were optimized with fractional factorial based on Taguchi. The capability of the isolates and consortium in hydrocarbon biodegradation was investigated in liquid medium of Bushnell-Hass with 150 ppm of Benzo(a)pyrene, during 14 days. Treatments included inoculation of isolates AP3 and BM1 and their consortium in presence and absence of extracted isolates biosurfactants and control (no isolate and biosurfactant). Based on the results of Benzo(a)pyrene degradation in the liquid medium, AP3 isolate, consortium and biosurfactant extracted from AP3 were selected for soil experiment. Four sets of biodegradation experiments were carried out with soil contaminated by 150 ppm of benzo(a)pyrene for 45 days, as follows: set 1: soil + AP3 isolate; set 2: soil + consortium; set 3: soil + consortium + AP3 biosurfactant and set 4: blank (soil). The residual concentrations of contaminant were extracted on days 15, 30 and 45 by dichloromethane solvent and analyzed using GC-FID.

The results revealed that strains AP3 and BM1 showed a significant potential to produce surface-active agents in the presence of Benzo(a)pyrene as substrate, reducing the surface tension to 43 and 46 mN/m, respectively. Taguchi experimental design method was applied in order to optimize the biosurfactant production by isolates. Results of experiments indicated that the optimum biosurfactant production conditions were found to be temperature of 35º C and  pH of 7, and glucose as water soluble carbon source. The produced biosurfactant reduced surface tension to 31/52 mN/m and 30/81 mN/m for BM1 and AP3, respectively. Biodegradation experiments of Benzo(a)pyrene in liquid cultures showed that the overall biodegradation efficiency of the individual isolates after 14 days was lower than consortium. Bacterial consortium enhanced degradation of contaminant to 87.3% (with addition of biosurfactant) compared to 27.6% of removal in presence of BM1 isolate. However, there was no statistically significant change in the degradation rates of contaminant in consortium with addition of AP3 and BM1 surfactant and surfactant free (87.3, 85.6 and 86.8%, respectively). The degradation of Benzo(a)pyrene was significantly enhanced in presence of AP3 biosurfactant at individual BM1 treatments (28.3 and 44.5 to 74.8%). Maximum degradation of Benzo(a)pyrene in contaminated soil was found (100%) in set 3: soil + consortium + AP3 biosurfactant. Based on GC-MS analyses, it degraded around 100% of penzo(a)pyrene, used as the sole carbon and energy source, at an initial concentration of 150 mg L-1, after 45 days of incubation, while alone consortium and isolate were able to remove 86% and 68% of hydrocarbon, respectively. Overall, these results provide evidence that consortium and AP3 biosurfactant could be potential candidates for further bioremediation.

The results revealed that the hydrocarbon removal efficiency of the consortium was higher than single species, and the final removal efficiency for the consortium could be reached in a considerably shorter time. The results suggest that biosurfactant-assisted bioremediation may be a promising practical bioremediation strategy for aged PAH-contaminated soils. It is evident from the results that the consortium alone and its producer species are both capable of promoting biodegradation to a large extent.