Seed Germination Test Research Articles

Upcycling food waste using black soldier fly larvae: Effects of further composting on frass quality, fertilising effect and its global warming potential

Abstract Using black soldier fly (Hermetia illucens [L.], Diptera: Stratiomyidae) larvae (BSFL) to upcycle urban solid waste into a growing medium for vegetable cultivation is a potential solution to ease cities’ over-reliance on food imports and excessive waste generation. However, rapid composting by BSFL may be insufficient to remove phytotoxins from the waste and further composting may be necessary. Through a growth experiment on pak choi (Brassica rapa), this study evaluated the optimum performance of BSFL frass at three composting stages (freshly produced, composted with forced aeration and naturally composted in larval rearing chambers) in biochar-based substrate cultivation. Plants cultivated in the composted BSFL frass treatments grew larger than those in fresh frass, with 10% naturally composted BSFL frass (v/v) producing the most biomass among all treatments. A seed germination test suggested the presence of phytotoxins in the fresh frass and frass Fourier-transform infrared spectroscopy (FTIR) analysis showed that the fresh frass potentially had the highest phenol concentration. In terms of greenhouse gas emission, a life cycle analysis showed that all three types of frass had a lower global warming potential compared to incineration, with the fresh frass having the lowest emission, the frass composted using forced aeration having the second lowest and the naturally composted frass, the highest emission. Therefore, further composting of BSFL frass with forced aeration would be the most feasible method considering both its compost quality and environmental impact.

Study of the Nutritional Increase in Organic Composts Obtained by Aerobic Biostabilization in the Management of Food Wastes

Composting is a sustainable alternative regarding an environmentally appropriate management of the organic fraction contained in the municipal solid wastes. To minimize nitrogen losses during the biostabilization process, due to ammonia volatilization, the present study aimed to evaluate the composting technique combined with the possible precipitation of struvite (MgNH4PO4.6H2O). A mixture containing food wastes was subjected to different experimental composting conditions with synthetic chemicals of magnesium and phosphorus—0.020 mol kg-1 (EXPI) and 1.8 mol kg-1 (EXPII), in addition to the control treatment (CONT). Experiments were carried out in closed systems, under forced aeration, over a period time of 56 days. In general, the addition of synthetic chemicals provided a nutritional increase in the organic composts obtained at the end of the experimental period in both conditions (EXPI and EXPII) compared to the treatment CONT. It was observed a total nitrogen conservation of about 21% and 122% in samples of composts obtained under the conditions EXPI and EXPII, respectively. Germination tests of lettuce seeds (Lactuca sativa) were also carried out to evaluate the agricultural applicability of the composts obtained in comparison with a commercial substrate (COM). A germination index with an average value of 87% was reached with the use of 100% of the compost obtained under the condition of greater conservation of total nitrogen (EXPII). Finally, the strategy considered for the conservation of nutrients in organic composts showed technical feasibility, indicating the formation of struvite and/or its analogues in the products obtained.

Maize seed germination inhibition test for pregnancy diagnosis in Zebu cows

Pregnancy diagnosis is an important part of good management and helps to maximizereproductive performance. Over time, different methods for detection of pregnancy in cows and other female domestic animals have been developed which include observation, physical examination, chemical tests and electronic instruments. Seed germination inhibition technique was carried out to detect pregnancy in Zebu cows. The urine samples collected from four pregnant cows, four non pregnant cows, four bulls and water (control) were subjected to seed germination test using maize seeds. Urine was collected between 5 and 7 am. Pregnant cows were confirmed by rectal palpation. The pH of the urine samples was determined before and after dilution and consequently, the urea concentration was also analyzed in the laboratory. The urine was diluted at the ratio of 1:4 with distilled water. Control test was also carried out with the addition of water only to the maize seeds. In each sterile Petri dish fifteen maize seeds were taken on the filter paper and 15mL of diluted urine was added. The seed germination inhibition percentages were observed after five days while shoot length growth inhibition was also observed after five days. Germination inhibition percentage of pregnant cows (64.16%) was significantly (P<0.05) higher compared to nonpregnant cows (34.18%), bull urine and water control. Shoot length of seeds germinated with distilled water had the highest value (4.38cm), seeds germinated with bull urine and non pregnant cow urine showed similarities while seeds germinated with pregnant cow urine had the least value (1.37cm) across the observations for shoot length growth inhibition. The result on pH showed clear differences in the pH of urine from pregnant (8.11- 8.25), non pregnant cows (6.05-7.04) and bull urine (6.35-7.34). The pH of the urine samples for nonpregnant cow and bull urine samples were similar to that of the control. Urea concentration of pregnant cow urine (11.06 mg/dL) was higher than that observed in bull urine 4.56 mg/dL and non pregnant cow urine 1.39 mg/dL. The study was able to validate that at 60% and above inhibition there is an indication of pregnancy while inhibition less than 60% shows the cow is non pregnant. Increased mean germination inhibition percentage and reduced shoot length in pregnant cow urine were indicative of pregnancy state.

Elucidation and Identification of an Antifungal Compound from Pseudomonas aeruginosa DA3.1 Isolated from Soil in Vietnam

Background: Fusarium sp. and Rhizoctonia sp. fungi have been always threats to short-term crops. In Vietnam, corn and soybean suffer serious losses annually. Therefore, it is necessary to utilize an environmentally friendly antifungal compound that is highly effective against phytopathogenic fungi. Pseudomonas sp. is a popular soil bacterial strain and well known for its high antifungal activity. Objectives: This study was carried out to evaluate and assess the antifungal activity of a local bacterial strain namely DA3.1 that was later identified as Pseudomonas aeruginosa. This would be strong scientific evidence to develop an environmentally friendly biocide from a local microorganism strain for commercial use. Methods: The antifungal compound was purified from ethyl acetate extraction of deproteinized cell culture broth by a silica gel column (CH2Cl2/MeOH (0% - 10% MeOH)). The purity of the isolated compound was determined by HPLC, and its molecular structure was elucidated using spectroscopic experiments including one-dimensional (1D) (1H NMR, 13C NMR, DEPT) and two-dimensional (2D) (HMBC and HSQC) spectra. The activity of the purified compound against Fusarium sp. and Rhizoctonia sp. fungi was measured using the PDA-disk diffusion method, and its growth-promoting ability was evaluated using the seed germination test of corn and soybean. Results: The results showed that the antifungal compound produced by Pseudomonas aeruginosa DA3.1 had a retention factor (Rf) of 0.86 on thin layer chromatography (TLC). Based on the evidence of spectral data including proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), distortionless enhancement by polarization transfer (DEPT), heteronuclear multiple bond correlation (HMBC), and heteronuclear single quantum coherence (HSQC), the chemical structure was elucidated as phenazine-1-carboxylic. The purified compound showed inhibitory activity against F. oxysporum and R. solani and exhibited the ability of the germination of corn and soybean seeds. The results revealed the benefit of native P. aeruginosa DA3.1 and phenazine-1-carboxylic acid for use as a biocontrol agent, as well as a plant growth promoter. Conclusions: The antifungal compound isolated from local Pseudomonas DA3.1 was identified as phenazine-1-carboxylic acid that posed high antifungal activity and was a plant germination booster.

In situ aerobic composting eliminates the toxicity of Ageratina adenophora to maize and converts it into a plant- and soil-friendly organic fertilizer

Ageratina adenophora has invaded many subtropical and tropical countries and caused tremendous ecological and economic losses. This necessitates a new way to use the debris left after clearing this plant. Therefore, the allelochemicals in fresh and aerobically composted A. adenophora plants (FA and CA, respectively) were compared, and their allelopathy against maize was evaluated. The results showed that CA decreased the allelochemicals (6-hydroxy-5-isopropyl-3,8-dimethyl-4a,5,6,7,8,8a-hexahydronaphthalen-2(1H)-one and 4,7-dimethyl-1-(propan-2-ylidene)-1,4,4a,8a-tetrahydronaphthalene-2,6(1H, 7H)-dione) by over 95% compared to FA. In a seed germination test, CA aqueous solutions improved the seed germination and seedling growth, whereas FA solutions led to opposite results. Chemical fertilizers (CF) plus FA resulted in much lower plant biomass and nutrient uptake than CF in a greenhouse experiment. Compared with CF, CF+CA showed positive effects on maize, soil microbial biomass and diversity and enzyme activities in the field. However, the compositions of the predominant microbes were almost unaffected by the application of CA and CF+CA. These significant findings extended our knowledge regarding the elimination of A. adenophora toxicity against other plants and soil microbes through allelochemical degradation in the composting process. In situ aerobic composting provides a new, simple and economical method to convert A. adenophora into a plant- and soil-friendly organic fertilizer.

Urinary reproductive hormones influence seed germination within diluted urine of heifers: alternative pregnancy diagnostic method

Experimental non-invasive pregnancy diagnostic techniques, such as seed germination testing in diluted urine, may serve as an alternative to standardized pregnancy diagnostic methods, but scientific validation of these methods is required. This study aimed to use Czech Fleckvieh heifers to investigate the influence of urinary reproductive hormones (oestrone sulphate, 17β-oestradiol, and pregnanediol3-glucuronide) on the germination success of seeds placed within their diluted urine, and further to verify the reliability of seed germination test for pregnancy diagnosis in this species. Mung bean and wheat seeds were germinated in two urine-water dilutions (1:4 and 1:14) for three days, using urine samples obtained from either pregnant or non-pregnant heifers. Germinated seeds were counted daily, and the shoot lengths were measured three days after placement in the urine. Levels of urinary reproductive hormones were determined using competitive heterogeneous enzyme immunoassays (EIAs). Despite the dilution rate used, final results indicated that the urine from pregnant heifers inhibited germination and growth in mung beans only. On the contrary, wheat germination rate was higher within the urine from pregnant females on days 1 and 2, when using a 1:14 dilution rate. For both seed species, correlations between urinary hormone profiles and seed germination parameters were found, depending on the day of the experiment and the rate of dilution used. The shoot lengths of mung bean seeds were significantly (P < 0.05) and negatively correlated with the profiles of all hormones analysed from the urine samples. Thus, urinary reproductive hormones influence seed germination and growth rate of wheat and mung beans, indicating the potential for this technique to be used for pregnancy determination in heifers.

Display of lead-binding proteins on Escherichia coli surface for lead bioremediation.

Cell surface display of heavy metal-binding proteins has been used to enhance the adsorption capacity of heavy metals and the engineered microbial cells can be potentially used for the bioremediation of heavy metals. In this study, the proteins PbrR, PbrR691, and PbrD from the Cupriavidus metallidurans strain CH34 were displayed on the extracellular membrane of Escherichia coli BL21 cells, with the N-domain of ice-nucleation protein as the anchor protein to achieve specific adsorption of lead ions (Pb2+ ) and bioremediation of lead in the soil. The localization of fusion proteins was confirmed by western blot analysis. We investigated the effects of fusion pattern, expression level, heavy metal concentration, and the presence of other heavy metal ions on the adsorption of Pb2+ by these engineered bacteria, and the optimal linker peptide (flexible linker) and inducer concentration (0.5 mM) were obtained. The engineered bacteria showed specific selectivity and strong adsorption capacity for Pb2+ . The maximum Pb2+ adsorption capacity of strains displaying the three proteins (PbrR, PbrR691, and PbrD) were 942.1-, 754.3-, and 864.8-μmol/g cell dry weight, respectively, which was the highest reported to date. The engineered E. coli bacteria were also applied to Pb2+ -contaminated soil and the detoxification effects were observed via the seed germination test and the growth of Nicotiana benthamiana in comparison with the control BL21, which provides the proof-of-concept for in situ remediations of Pb2+ -contaminated water or soil.

Physicochemical comsposition of Kenaf (Hibiscus cannabinus L.) seed under different storage temperature

Kenaf is an annual plant grown for its fibre which basically depend on the seed viability, for its maximum growth and production. The seed viability and vigor in turn depend on storage condition. There is insufficient information on physicochemical composition of kenaf seed in relation to seed viability. The present study was performed to know the physicochemical composition of the kenaf seed at different storage temperature in other to improve upon rapid loss of seed viability in kenaf. Four varieties of kenaf seed were obtained from I.A.R. & T seed unit. The seeds were stored at 00C (Unviable seed), 2.20C (Lower temperature), 350C (Ambient temperature), 280C (Cold room temperature which serve as control) for period of 8 months. Seed germination test and weight was performed before and after the experiment. Proximate analysis (Crude protein, Moisture, Carbohydrate, Ash, Crude fibre, Crude fat) and Phytochemicals (Total phenolics, Steroid and Total Flavonoids were also determined). The result shows that there is significant difference in all the parameters studied, for all the storage temperatures as compared with the control (280C) among the varieties except from ifeken 100 where the was no significant difference in Crude fibre and Ash content for seed under ambient temperature as compared with the control. However, the level of tolerance to different storage temperature among the varieties following the order Ifeken 400 >Tianung 2 > Cuba 108>Ifeken 100.Keywords: Kenaf, Storage, Seed germination, Seed weight, Temparature, Seed viability, Proximate, Flavonoid, Phenolics.

Environmental impact of utilization of \u201cproduced water\u201d from oil and gas operations in turfgrass systems

This study attempted to use produced water (PW) to irrigate turfgrass species, Cynodon dactylon and Paspalum sp. Assessment on established grasses, heavy metal accumulation and germination tests for weeds and turf grass seeds were conducted to evaluate the impact of PW irrigation. C. dactylon depicted lower tolerance while Paspalum sp. showed better tolerance capacity towards PW. C. dactylon grown from seeds under greenhouse conditions were not able to tolerate more than 30% concentration of PW (4.5% salinity). In comparison to tap water irrigated turf grass, Paspalum sp. was found to accumulate higher concentrations of V and Pb in shoots and Cr, Ni and As in roots. The results of seed germination tests recommended that irrigation with PW is to be performed after turfgrass establishment. Germination tests also revealed that PW could encourage growth of the weed—Chloris virgata while it could discourage growth of Amaranthus viridis and Launaea mucronata. This study suggests that PW could be used for turfgrass as an alternative water resource but only after further research on the long-term scale.

Optimized production of single-use plastic-Eucalyptus wood char composite for application in soil

Co-pyrolysis of Eucalyptus wood (EW) and Single-use plastic (SUP) can be a sustainable and green technological option ensuring optimum resource recovery and plastic waste management in a circular economy. This study aims to optimize the variables of pyrolysis [temperature (300, 400, 500, 600 °C), residence time (90, 120, 150 min), and proportion of plastic (w/w - 0.25, 0.33)] for application of SUP - EW char composite in soil. Statistical analysis showed that all three process variables had significant influence on properties of the char. With temperature and residence time, the char became dense, carbonaceous, ash-rich, aromatic, and alkaline for both the proportions of SUP in the feed. Further characterization also revealed that the highest plant extractable concentrations of major nutrients, cation exchange capacity, and electrical conductivity of char composite were recorded with temperatures of 400–500 °C, residence time of 120 min, and 33% (w/w) of SUP. The surface morphology analysis revealed the char to have a porous structure with a coating of plastic at lower temperatures of 300 °C and an increase in microporosity at higher temperatures of 500, 600 °C. Significant positive correlations between radicle root growth and prominent plant growth parameters observed through seed germination test indicate the char’s potential applicability in soil. The optimized process parameters of char obtained through regression modeling for application in soil were 415.2 °C, 125.2 min, and 0.325 (w/w) proportion of SUP. The highest mean seed length of ≈17.5 cm observed at 400 °C, 120 min, and 0.33 (w/w) proportion of SUP was consistent with these optimized parameters. Soil incubation test further showed that amendment with optimized char composite significantly improved its properties with a 3.7-fold increase in soil fertility index at 5% rate of application. So, the application of optimized SUP - EW char composite could significantly improve the properties of soil while promoting greener sustainable development through ideal utilization of the so far mismanaged waste resources.

Storage Conditions Deteriorate Cotton and Wheat Seeds Quality: An Assessment of Farmers’ Awareness in Pakistan

Seed quality is accessed by appropriate seed germination, seed moisture contents, insect/pathogen infestations and seed vigor. Seed storage conditions are essential to protect from deterioration. In this study, knowledge and practices of wheat and cotton seeds storage were accessed among commercial seed growers (CSGs) and non-commercial seeds growers (NCSGs) in the Vehari District of Pakistan, while samples of stored wheat and cotton seeds were also collected to assess the quality of stored seeds. Stored seeds in the study area were contaminated by a variety of fungi, with infestation percentages reaching 13% for wheat and 20.7% for cotton in seeds from NCSGs, compared to 9% (wheat) and 9.5% (cotton) in seeds from CSGs. The majority of seed growers (75.0%) did not have any training on seed storage. The growers (60.9%) were unaware that seed should not be stored in closed polythene bags and most (62.2%) were not well aware about seed-borne crop diseases. Most growers did not maintain the temperature and humidity of storage rooms (82.7%) and did not calculate the seed rate before sowing after seed germination tests (87.2%). However, seed dressing with fungicides was implemented by most farmers (69.9%). Controlling the temperature of the seed storage was significantly influenced by growers’ age, while controlling the humidity of the seed storage was significantly influenced by growers’ farming experience. Seed dressing with fungicides was positively associated with the graduation level of growers, while checking seed maturity was positively associated with the higher education (Master’s level) of growers. There was a lack of active information centers in the study areas and a lack of agricultural information provision to farmers. Awareness regarding bad-quality seeds should be initiated to increase growers’ knowledge. Training programs for providing adequate knowledge to growers and skills in seed storage should be organized. Legislation regarding the seed business and seed storage protective measures should be enforced to minimize problems by a seed-borne inoculum and deterioration of seed quality.

Allelopathy of uncomposted and composted invasive aster (Ageratina adenophora) on ryegrass

In many areas invaded by Ageratina adenophora, the piles of A. adenophora residue need to be safely treated and economically utilized. To explore a new potential use for these residues, on-site aerobic composting, seed germination test and greenhouse experiment were conducted to compare the phytotoxic allelochemicals in uncomposted and composted A. adenophora plants (UA and CA, respectively) and their influence on ryegrass seed germination and seedling growth. The phytotoxicants 4,7-dimethyl-1-(propan-2-ylidene)-1,4,4a,8a-tetrahydronaphthalene-2,6(1H,7H)-dione (DTD) and 6-hydroxy-5-isopropyl-3,8-dimethyl-4a,5,6,7,8,8a-hexahydronaphthalen-2(1 H)-one (HHO) in UA decreased by 10.09 and 11.01 times in CA on average, respectively. Aqueous extracts of CA increased the seed germination rate, root dehydrogenase activity, leaf chlorophyll content and nitrate reductase activity; those of UA behaved oppositely. Compared with chemical fertilizers (CF), CF + CA promoted plant growth, increased plant nutrient uptake, and resulted in higher soil available nutrients, enzyme activity and microbial biodiversity, whereas CA alone had similar or better influences on plants and soils than CF. The predominant bacterial and fungal composition was the same in the soils supplied with CA and CF + CA. Therefore, on-site aerobic composting eliminated the phytotoxicity of CA and provided a new, simple and economical approach for the potential use of A. adenophora biomass as a plant- and soil-friendly organic fertilizer.

Feasibility of Vermicomposting of Spent Coffee Grounds and Silverskin from Coffee Industries: A Laboratory Study

In the coffee industry, several by-products are generated during the production and consumption of coffee and represent an important waste from an environmental viewpoint. For improving the knowledge about this issue, a laboratory vermicomposting study of coffee silverskin (CS) and spent coffee grounds (SCG) spiked with mature horse manure (HM) in different proportions and using earthworm Eisenia andrei was carried out. The 60-day study focused on biological parameters such as total biomass gain, growth rate, cocoon production, and mortality. This study also investigated whether the vermicompost obtained could be useful and lacked toxicity through a seed germination test using hybrid wheat seeds. Results showed a disparity depending on the type of residue and the mixture used. Best options were those treatments with a medium–low amount of residue; 25% for SCG and 25% or 50% for CS. In addition, lack of toxicity was confirmed in all treatments. In conclusion, it is possible to carry out a vermicomposting of SCG and CS with some specific features.

English

The seed germination test under lead (Pb) stress could be a quick test to understand plant tolerance to this heavy metal. The aim of this study was to compare the germination behavior of Raphanus sativus L. germinated in solution with different increasing concentration of lead, also to assess its accumulation and toxicity. The test was carried out in an incubator at 25 ± 1°C for 7 days and in a greenhouse for 11 weeks. Lead caused significant germination behavioral disturbances by changing the velocity coefficient and germination kinetics, with reducing the rate of early and final germination, however, the duration of germination was lengthened. Pb reduced the levels of the chlorophyll, delta-aminolevulinic acid dehydratase (ALAD) activity and growth. It increased lipid peroxidation and induced a significant accumulation of proline, positively correlated with Pb accumulation. Pb has a depressive effect on germination and causes disruptive disturbances of R..  sativus L. revealed by changes in non-enzymatic antioxidants, ALAD activity and growth. Radish has a capacity to accumulate Pb. The present results provide a model for detecting natural compounds able to improve seed germination of radish and counteract the harmful effects of lead.   Key words: Radish, concentration, rate, accumulation, proline, lipid peroxidation, chlorophyll.

Toxicity assessment of carmine and its interaction with calf thymus DNA

Carmine (CRM) is a colouring agent, extensively used in a variety of foods, beverages, cosmetics and pharmaceuticals. A battery of in vitro toxicity tests and chemical interaction studies of CRM with calf thymus DNA (ctDNA) have been conducted. Hemolysis assay clearly revealed the cytotoxic potential of CRM while Allium cepa and seed germination tests for phytotoxicity of CRM were also positive. DNA binding studies withplasmid nicking assay, clearly affirmed the genotoxic potential of CRM. The formation of CRM–ctDNA complex was suggested by UV-visible absorption and fluorescence spectra. The binding constant of CRM–ctDNA complex determined by ITC was found to be 1.72 x 106 M −1. It also revealed the negative ΔH and ΔS values, indicating the role of hydrogen bonds and Van der Waals interactions in the formation of CRM–ctDNA complex. A remarkable (43.4%) displacement of Hoechst as compared to acridine orange (100%) suggests probable disruption of groove which might be possible due to the large size of CRM. Intercalatory mode of CRM binding was further confirmed by significant increase in double helix melting temperature of ctDNA and changes it's in circular dichroism spectra. Molecular docking also supported the notion that DNA binding involved both modes i.e. intercalatory as well as groove binding; moreover, it is consistent with the binding energies determined from ITC. In a nutshell, CRM is significantly cytotoxic to human and plant systems with its remarkable genotoxic potential too, wherein it targets DNA as a partial intercalator and ultimately break its backbone. Communicated by Ramaswamy H. Sarma

Determinação da metodologia para o teste de germinação de sementes de Eucalyptus urophylla S. T. Blake (Myrtaceae)

Eucalyptus urophylla S. T. Blake é uma das principais espécies de eucaliptos cultivadas. Entretanto, não existem recomendações para o teste padrão de germinação de E. urophylla. Assim, o objetivo foi determinar a melhor metodologia para a condução do teste de germinação de sementes de E. urophylla. O experimento foi dividido em duas etapas. Na primeira, foram testados dois substratos (sobre papel mata-borrão e areia) e seis temperaturas (constantes de 15, 20, 25, 30, 35ºC e alternada de 20-30ºC, entre noite e dia, respectivamente) na condução do teste de germinação. Na segunda etapa, foi selecionado o substrato mais indicado no experimento anterior e testado em dois lotes, nas seis temperaturas citadas anteriormente. Foram avaliadas a germinação, primeira contagem, índice de velocidade e tempo médio de germinação. O experimento foi realizado em delineamento inteiramente casualizado com quatro repetições e os tratamentos foram dispostos em esquema fatorial de 2 x 6 para ambas as etapas. Na comparação da germinação entre os lotes, observou-se que o lote 1 apresentou menor desempenho do que o lote 2 nas condições de temperaturas extremas. O teste de germinação de sementes de E. urophylla deve ser realizado a 30 ou 35°C com semeadura sobre papel ou areia, e com contagem inicial e final aos quatro e 10 dias após a semeadura, respectivamente. Com base nesta pesquisa, mais testes podem ser realizados, para outros lotes e sementes de E. urophylla de outras procedências, para garantir a confirmação dos resultados.

Diesel-Contaminated Soil Washing by Mixed Nonionic Surfactant Emulsion and Seed Germination Test

Petroleum hydrocarbons are applied in various energy activities. If accidents happen, they may result in environmental contamination, especially in soil. Petroleum hydrocarbons have low evaporation rates and are adsorbed on the soil surface, making it necessary to treat contaminated soil before the pollutants spread to other areas. Soil washing with surfactant solution is a method used to treat petroleum hydrocarbon contamination. The process relies on surfactant properties which reduce surface tension and desorb diesel from soil particles prior to flushing out with water. The relationship between efficiency of diesel extraction from contaminated soil and factors of both single surfactants (Span20, Tween20, Tween80, Dehydol LS9) and mixed surfactants (Span20+Tween20, Span20+Tween80, Span20+Dehydol LS9) were investigated including hydrophile-lipophile balance (HLB) and interfacial tension (IFT) to select a suitable surfactant. Diesel was analyzed by GC-FID. Findings revealed that extraction efficiency significantly increased when the HLB of the surfactant increased in every solution pair (p = 0.05). Span20+Dehydol LS9 solution with HLB 12 showed the lowest IFT (17.767 ± 0.013 mN/m) and the highest diesel extraction efficiency (66.2%). The water washing process, repeated twice after washing with 1% (w/v) Span20+Dedydol LS9, resulted in less toxicity on germination and growth of tomato, rice, and green bean compared with diesel washing solution and fresh washing solution. Diesel-contaminated soil washing with mixed surfactant is an interesting alternative as an environmentally friendly soil treatment.

A phytotoxicity assessment of the efficiency 2,4-D degradation by different oxidative processes

Highly stable compounds such as dichlorophenoxyacetic acid (2,4-D), which are present in the commercial herbicide Tordon®, are difficult to degrade. Therefore, the objective of this work was to degrade 2,4-D present in Tordon® using different oxidative processes, such as anodic oxidation, Fenton reactions, electro-Fenton, photoelectro-oxidation and photoelectro-Fenton processes. An oxide electrode with the nominal composition Ti/Ru0.3Ti0.7O2 was prepared and inserted into an electrochemical cell containing 100 mL of 0.05 mol L−1 Na2SO4 (pH 3) and 100 mg L−1 of Tordon®. Electrolysis was performed applying a constant current of 50 mA cm−2 for 2 h. The concentration of Fenton's reagent was varied from 5 to 10 mg L−1 (Fe2+), and from 50 to 100 mg L−1 (H2O2). Chemical analyses of the total organic carbon (TOC) and the chemical oxygen demand (COD) were performed whilst high-performance liquid chromatography (HPLC) was used to monitor the degradation. A phytotoxicity assessment was performed using cucumber seeds as bioindicators. Germination tests were performed using cucumber seeds in the presence of the solutions collected after the application of the oxidative processes. Several analyses were carried out to determine the following: total protein content, the extent of lipid peroxidation, activity of superoxide dismutase, hydrogen peroxide content, catalase activity, and glutathione reductase activity. Oxidation of 2,4-D was observed in all of the oxidative processes, and significant results for the removal of TOC and COD were obtained. Anodic oxidation, and the Fenton and photoelectro-oxidation processes were the least efficient, affording 2,4-dichlorophenol, 2-chlorohydroquinone, and 2-chlorobenzoquinone as by-products. The electro-Fenton and photoelectro-Fenton processes were the most efficient, giving short-chain acids as the main by-products. The formation of these by-products directly affected the phytotoxicity results. The processes that formed short-chain by-products did not generate significant oxidative stress during seed growth, and therefore, seed germination tests were successful.

Interactive Effects of Ni, Cr, Co, Ca, and Mg in Seeds Germination Test: Implications for Plant Growth in Ultramafic Soils

Interactive Effects of Ni, Cr, Co, Ca, and Mg in Seeds Germination Test: Implications for Plant Growth in Ultramafic Soils

Potential PGPR Properties of Cellulolytic, Nitrogen-Fixing, Phosphate-Solubilizing Bacteria in Rehabilitated Tropical Forest Soil.

In the midst of the major soil degradation and erosion faced by tropical ecosystems, rehabilitated forests are being established to avoid the further deterioration of forest lands. In this context, cellulolytic, nitrogen-fixing (N-fixing), phosphate-solubilizing bacteria are very important functional groups in regulating the elemental cycle and plant nutrition, hence replenishing the nutrient content in forest soils. As is the case for other potential plant growth-promoting (PGP) rhizobacteria, these functional bacteria could have cross-functional abilities or beneficial traits that are essential for plants and can improve their growth. This study was conducted to isolate, identify, and characterize selected PGP properties of these three functional groups of bacteria from tropical rehabilitated forest soils at Universiti Putra Malaysia Bintulu Sarawak Campus, Malaysia. The bacteria were isolated based on their colonial growth on respective functional media, identified using both molecular and selected biochemical properties, and were assessed for their functional quantitative activities as well as PGP properties based on seed germination tests and indole-3-acetic acid (IAA) production. Out of the 15 identified bacterial isolates that exhibited beneficial phenotypic traits, a third belong to the genus Burkholderia and a fifth to Stenotrophomonas sp., with both genera consisting of members from two different functional groups. The results of the experiments confirm the multiple PGP traits of some selected bacterial isolates based on their respective high functional activities, root and shoot lengths, and seedling vigor improvements when bacterized on mung bean seeds, as well as significant IAA production. The results of this study suggest that these functional bacterial strains could potentially be included in bio-fertilizer formulations for crop growth on acid soils.