Effect Of Soil Microorganisms Research Articles

Rhizosphere Microbe Affects Soil Available Nitrogen and Its Implication for the Ecological Adaptability and Rapid Growth of Dendrocalamus sinicus, the Strongest Bamboo in the World.

The interaction between soil microbes and plants has a significant effect on soil microbial structure and function, as well as plant adaptability. However, the effect of soil micro-organisms on ecological adaption and rapid growth of woody bamboos remains unclear. Here, 16S rRNA and ITS rRNA genes of rhizosphere micro-organisms were sequenced, and the soil properties of three different types of Dendrocalamus sinicus were determined at the dormancy and germination stages of rhizome buds. The result showed that each type of D. sinicus preferred to absorb ammonia nitrogen (NH4+-N) rather than nitrate nitrogen (NO3--N) and required more NH4+-N at germination or rapid growth period than during the dormancy period. In total, nitrogen fixation capacity of soil bacteria in the straight type was significantly higher than that in the introduced straight type, while the ureolysis capacity had an opposite trend. Saprophytic fungi were the dominant fungal functional taxa in habitat soils of both straight and introduced straight type. Our findings are of great significance in understanding how soil microbes affect growth and adaptation of woody bamboos, but also for soil management of bamboo forests in red soil.

Endophytic infection increases the belowground over-yielding effects of the host grass community mainly by increasing the complementary effects.

Increases in plant species diversity may increase the community diversity effect and produce community over-yielding. Epichloë endophytes, as symbiotic microorganisms, are also capable of regulating plant communities, but their effects on community diversity effects are often overlooked. In this experiment, we investigated the effects of endophytes on the diversity effects of host plant community biomass by constructing artificial communities with 1-species monocultures and 2- and 4-species mixtures of endophyte-infected (E+) and endophyte-free (E-) Achnatherum sibiricum and three common plants in its native habitat, which were potted in live and sterilized soil. The results showed that endophyte infection significantly increased the belowground biomass and abundance of Cleistogenes squarrosa, marginally significantly increased the abundance of Stipa grandis and significantly increased the community diversity (evenness) of the 4-species mixtures. Endophyte infection also significantly increased the over-yielding effects on belowground biomass of the 4-species mixtures in the live soil, and the increase in diversity effects on belowground biomass was mainly due to the endophyte significantly increasing the complementary effects on belowground biomass. The effects of soil microorganisms on the diversity effects on belowground biomass of the 4-species mixtures were mainly derived from their influences on the complementary effects. The effects of endophytes and soil microorganisms on the diversity effects on belowground biomass of the 4-species communities were independent, and both contributed similarly to the complementary effects on belowground biomass. The finding that endophyte infection promotes belowground over-yielding in live soil at higher levels of species diversity suggests that endophytes may be one of the factors contributing to the positive relationship between species diversity and productivity and explains the stable co-existence of endophyte-infected Achnatherum sibiricum with a variety of plants in the Inner Mongolian grasslands.

Interactions Between Phenolic Acids and Microorganisms in Rhizospheric Soil From Continuous Cropping of Panax notoginseng.

Large-scale intensive cultivation has made continuous cropping soil sickness more serious for Panax notoginseng in Yunnan. Autotoxic substances can promote the occurrence of continuous cropping soil sickness. Phenolic acids exert a strong autotoxic effect on P. notoginseng. Based on UPLC-MS/MS, the levels of six phenolic acids with the strongest autotoxicity of P. notoginseng rhizospheric soil were tested. Based on Illumina MiSeq high-throughput sequencing technology, the variation in the microbial diversity in the rhizospheric soil was used as an index to explore the interactions between phenolic acids and the soil microorganisms of the P. notoginseng rhizosphere. (1) Continuous P. notoginseng cropping significantly changed the microbial community structure. Continuous cropping increased bacterial Chao1 index and Shannon index and decreased fungal Shannon index. After P. notoginseng disease, bacterial Shannon index reduced and fungal Chao1 index decreased. (2) Phenolic acid significantly changed the bacterial community structure. VA significantly reduced the bacterial Shannon index. Exogenous p-HA, FA, SA, and VA significantly increased the fungal Chao1 index and p-HA showed the most significant effect. Para-HA affected bacterial specificity, and VA affected fungal specificity. (3) VA was positively correlated with most fungi and bacteria. Para-HA was positively correlated with Lelliottia and Flavobacterium. Para-HA was also positively correlated with plant pathogens (Fusarium and Ilyonectria). Para-HA and VA were able to promote the growth of primary pathogenic bacteria. Thus, p-HA and VA are the main phenolic acid-autotoxin substances in P. notoginseng under continuous cropping. (4) A correlation analysis of soil environmental factors associated with fungal and bacterial communities showed that AK, TN, OM, and HN were most strongly correlated with soil microorganisms. (5) The microorganisms in the rhizosphere of 3-year-old soil planted with P. notoginseng exhibited obvious effects on the degradation of the four phenolic acids. The effect of soil microorganisms on phenolic acids was first-order kinetic degradation with a high degradation rate and a half-life of less than 4.5 h. The results showed that phenolic acids could promote the growth of pathogenic bacteria. And the interaction between rhizospheric soil microorganisms and phenolic acids was the main cause of the disturbance of P. notoginseng rhizosphere microflora.

Arbuscular Mycorrhizal Fungi Are an Influential Factor in Improving the Phytoremediation of Arsenic, Cadmium, Lead, and Chromium.

The increasing expansion of mines, factories, and agricultural lands has caused many changes and pollution in soils and water of several parts of the world. In recent years, metal(loid)s are one of the most dangerous environmental pollutants, which directly and indirectly enters the food cycle of humans and animals, resulting in irreparable damage to their health and even causing their death. One of the most important missions of ecologists and environmental scientists is to find suitable solutions to reduce metal(loid)s pollution and prevent their spread and penetration in soil and groundwater. In recent years, phytoremediation was considered a cheap and effective solution to reducing metal(loid)s pollution in soil and water. Additionally, the effect of soil microorganisms on increasing phytoremediation was given special attention; therefore, this study attempted to investigate the role of arbuscular mycorrhizal fungus in the phytoremediation system and in reducing contamination by some metal(loid)s in order to put a straightforward path in front of other researchers.

Rhizosphere enzyme activities and microorganisms drive the transformation of organic and inorganic carbon in saline\u2013alkali soil region

Western Jilin Province is one of the world's three major saline–alkali land distribution areas, and is also an important area of global climate change and carbon cycle research. Rhizosphere soil microorganisms and enzymes are the most active components in soil, which are closely related to soil carbon cycle and can reflect soil organic carbon (SOC) dynamics sensitively. Soil inorganic carbon (SIC) is the main existing form of soil carbon pool in arid saline–alkali land, and its quantity distribution affects the pattern of soil carbon accumulation and storage. Previous studies mostly focus on SOC, and pay little attention to SIC. Illumina Miseq high-throughput sequencing technology was used to reveal the changes of community structure in three maize fields (M1, M2 and M3) and three rice fields (R1, R2 and R3), which were affected by different levels of salinization during soil development. It is a new research topic of soil carbon cycle in saline–alkali soil region to investigate the effects of soil microorganisms and soil enzymes on the transformation of SOC and SIC in the rhizosphere. The results showed that the root—soil—microorganism interaction was changed by saline–alkali stress. The activities of catalase, invertase, amylase and β-glucosidase decreased with increasing salinity. At the phylum level, most bacterial abundance decreases with increasing salinity. However, the relative abundance of Proteobacteria and Firmicutes in maize field and Firmicutes, Proteobacteria and Nitrospirae in rice field increased sharply under saline–alkali stress. The results of redundancy analysis showed that the differences of rhizosphere soil between the three maize and three rice fields were mainly affected by ESP, pH and soil salt content. In saline–alkali soil region, β-glucosidase activity and amylase were significantly positively correlated with SOC content in maize fields, while catalase and β-glucosidase were significantly positively correlated with SOC content in rice fields. Actinobacteria, Bacteroidetes and Verrucomicrobia had significant positive effects on SOC content of maize and rice fields. Proteobacteria, Gemmatimonadetes and Nitrospirae were positively correlated with SIC content. These enzymes and microorganisms are beneficial to soil carbon sequestration in saline–alkali soils.

Effect of soil microorganisms and labile C availability on soil respiration in response to litter inputs in forest ecosystems: A meta-analysis.

Litter inputs can influence soil respiration directly through labile C availability and, indirectly, through the activity of soil microorganisms and modifications in soil microclimate; however, their relative contributions and the magnitude of any effect remain poorly understood. We synthesized 66 recently published papers on forest ecosystems using a meta‐analysis approach to investigate the effect of litter inputs on soil respiration and the underlying mechanisms involved. Our results showed that litter inputs had a strong positive impact on soil respiration, labile C availability, and the abundance of soil microorganisms, with less of an impact related to soil moisture and temperature. Overall, soil respiration was increased by 36% and 55%, respectively, in response to natural and doubled litter inputs. The increase in soil respiration induced by litter inputs showed a tendency for coniferous forests (50.7%)> broad‐leaved forests (41.3%)> mixed forests (31.9%). This stimulation effect also depended on stand age with 30‐ to 100‐year‐old forests (53.3%) and ≥100‐year‐old forests (50.2%) both 1.5 times larger than ≤30‐year‐old forests (34.5%). Soil microbial biomass carbon and soil dissolved organic carbon increased by 21.0%‐33.6% and 60.3%‐87.7%, respectively, in response to natural and doubled litter inputs, while soil respiration increased linearly with corresponding increases in soil microbial biomass carbon and soil dissolved organic carbon. Natural and doubled litter inputs increased the total phospholipid fatty acid (PLFA) content by 6.6% and 19.7%, respectively, but decreased the fungal/bacterial PLFA ratio by 26.9% and 18.7%, respectively. Soil respiration also increased linearly with increases in total PLFA and decreased linearly with decreases in the fungal/bacterial PLFA ratio. The contribution of litter inputs to an increase in soil respiration showed a trend of total PLFA > fungal/bacterial PLFA ratio > soil dissolved organic carbon > soil microbial biomass carbon. Therefore, in addition to forest type and stand age, labile C availability and soil microorganisms are also important factors that influence soil respiration in response to litter inputs, with soil microorganisms being more important than labile C availability.

Effects of salinity on the soil microbial community and soil fertility

Saline area is an important reserve resource of arable land, however, the effects of soil microorganisms on the soil fertility in saline coastal ecosystems remain poorly understood. The salinity effects on soil microorganisms, nutrient availabilities and their relationships were studied in soils along a salinity gradient. A total of 80 soil samples were collected from 16 sites at four salinity levels (non-saline soil, salt content<1 g kg−1; low salinity soil, salt content=1−2 g kg−1; middle salinity soil, salt content=2−4 g kg−1; high salinity soil, salt content>4 g kg−1). The results showed that the salinity increased soil pH and exchangeable Na percent, but decreased soil organic matter, soil exchangeable K, and soil microbial biomass. Both the abundance and community composition of soil bacteria and fungi were significantly different between the non-saline and the saline soils. The predominant genera of soil bacteria (Planctomyces and Archangium, positive for carbon fixation) and fungi (Hydropisphaera, efficient in lignin degradation) changed with the increasing soil salinity and the decreasing soil organic matter. In summary, soil salinity changed the abundances of soil bacterial, fungal, and arbuscular mycorrhizal communities and, subsequently, affected their function in saline coastal ecosystems.

Effect of soil microorganisms on arsenite oxidation in paddy soils under oxic conditions

The contribution of abiotic and biotic processes to the oxidation of arsenite [As(III)] when anaerobic paddy soils were shifted to oxic conditions was investigated. Soil slurries were first incubated under reducing conditions to allow indigenous arsenic (As) to be dissolved into the liquid phase as As(III), and were then switched to oxic incubation conditions with shaking. One day after switching to oxic incubation, As(III) almost disappeared from the liquid phase without any increase of arsenate [As(V)], suggesting that dissolved As(III) was co-precipitated or adsorbed on the soil solid phase. X-ray adsorption near-edge structure (XANES) analysis revealed that the predominant species of As in the solid phase before the oxic incubation was As(III), ranging from 74 to 85% of total As. After 1 d of the oxic incubation, the proportion of As(III) decreased to 46–47%. This oxidation step was an abiotic process and 28–38% of As(III) was oxidized per day on average. However, the abiotic oxidation ceased within 24 h probably due to passivation of reactive sites on the mineral surface. Afterward, a second slow oxidation step (2.5–2.8% per day on average) became predominant. Interestingly, this step was microbiologically mediated, since it did not occur in sterilized soil slurries. Determination of putative arsenite oxidase gene (aioA) sequences suggested that arsenite-oxidizing bacteria are actually present in our soil slurries. Our results suggest that microbial As(III) oxidation accounts for more than 30% of total As(III) oxidation, and thus it is an important process especially after abiotic oxidation ceases.

Effects of Inoculation of PAH-degrading Bacteria and Arbuscular Mycorrhizal Fungi on Responses of Ryegrass to Phenanthrene and Pyrene

In order to investigate the effects of soil microorganisms on biochemical and physiological response of plants to PAHs, PAH-degrading bacteria (Acinetobacter sp.) and/or arbuscular mycorrhizal fungus (Glomus mosseae) were inoculated with ryegrass (Lolium multiflorum) under four different concentrations of phenanthrene and pyrene (0, 50 + 50, 100 + 100, 200 + 200 mg kg–1) in soils. Acinetobacter sp. played limited roles on the growth of ryegrass, chlorophyll content, water soluble carbohydrate content, malondialdehyde (MDA) content, activities of superoxide dismutase (SOD) and peroxidase (POD) in shoot. By contrast, G. mosseae significantly (P < 0.01) increased ryegrass growth, partially by improving the photosynthetic activity through increasing the chlorophyll content in shoot. G. mosseae also significantly decreased MDA content in shoot. However, G. mosseae significantly increased SOD activity in shoot, which seemed to be resulted from significantly higher pyrene concentrations in shoot. The present study suggested that AM fungi could reduce the damage of cell membranes caused by free radicals, which may be one of the mechanisms involved in mycorrhizal alleviation of plant stress under PAHs. The present study indicated that the dual inoculation was superior to single inoculation in remediating PAHs contaminated soils. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.

Response of Giant Ragweed (Ambrosia trifida), Horseweed (Conyza canadensis), and Common Lambsquarters (Chenopodium album) Biotypes to Glyphosate in the Presence and Absence of Soil Microorganisms

In previous research conducted on nonweed species, the efficacy of glyphosate was shown to be greater in unsterile soils compared to sterile soils and soil microorganisms were found to play an important role in glyphosate efficacy. Conducting greenhouse studies in microbe-free soil may therefore produce unreliable data, leading to erroneous conclusions. The objective of this study was to determine the effect of soil microorganisms on the response of glyphosate-resistant and -susceptible biotypes of three problematic weeds of the midwestern United States: giant ragweed, horseweed, and common lambsquarters. A greenhouse dose–response study was conducted on each of the three weed species grown in sterile and unsterile field soil, and the dry weight response of roots and shoots was measured. The three weed species responded differently to glyphosate when grown in the sterile and unsterile soil; that is, in the presence and absence of soil microbes. Soil microbes influenced the response of the susceptible and resistant giant ragweed biotypes and the susceptible common lambsquarters, but not the tolerant common lambsquarters or either horseweed biotype. The different responses of the three species to glyphosate in the presence and absence of soil microbes demonstrates that rhizosphere interactions are fundamental to the mode of action of glyphosate. These findings suggest that the range of tolerance to glyphosate observed in weeds and the evolution of resistance in weed biotypes may also be influenced by rhizosphere interactions. The soil media used in dose–response screenings to identify susceptible and resistant weed biotypes is very important. Unsterile field soil should be incorporated into growth media when conducting dose–response screenings to avoid false-positive results. In addition, researchers performing glyphosate dose–response assays should be aware of these findings.

Effect of soil microorganisms on the sorption of zinc and lead compounds by goethite

AbstractThe objectives of this study were (1) to determine the effect of microorganisms during in‐vitro incubation on the amount of Zn and Pb from solution retained on goethite precipitated as coatings on a sand matrix and (2) to evaluate accumulation of heavy metals in the biomass of soil microorganisms in the fresh soil samples using an extractive approach. A mixture of colonies of cultivated microorganisms extracted from a Haplic Luvisol (Russia) and an Antropi‐urbic Regosol (Germany) were used to prepare the cell and the microbial‐debris suspensions. The concentrations of Zn and Pb in the studied solutions supplied with microbial suspensions and/or goethite coated sand were 0.1 mM (130.8 and 414 mg kg–1 of sand, respectively). Exchangeable forms of metals were determined by extraction with 10 mL of 1.0 M KNO3. Nonexchangeable forms of Zn and Pb were recovered using 40 mL of 0.3 M NH2OH‐HCl in 1 M HNO3. Concentrations of Pb increased in the solutions and decreased on the surface of the Fe‐mineral due to living microorganisms. In comparison to incubation of heavy‐metal solutions with goethite only, the absolute concentrations of nonexchangeable forms of metal were reduced by microbial suspension to a greater extent than those of the exchangeable forms, whereas the relative content of both fractions decreased by a factor of almost two. Sorption of Pb by goethite was inversely correlated with the concentration of organic C in the solution. Microorganisms clearly influenced the Zn sorption by goethite at concentrations of Corg &gt; 400 mg L–1. The amount of Zn retained was decreased primarily due to decreasing Zn portions in the exchangeable fraction. Microbial debris prepared by autoclaving reduced the Pb sorption by goethite similar to the results for living cells. Living microorganisms accumulated more Zn than did microbial debris. The data of this paper show that a direct determination of heavy‐metal accumulation in soil microorganisms by extraction with 2.0 M KCl as well as by extraction with 1 M CH3COONH4 at the natural pH of the soils after chloroform fumigation of fresh soils samples with different concentrations of organic C was not possible.

Effect of soil microorganisms on viability of sclerotia of Ciborinia camelliae, the causal agent of camellia flower blight

Two isolates each of Trichoderma virens and Coniothyrium minitans, four of T. longipile, and one each of T. tomentosum and Clonostachys rosea, all known to be sclerotial parasites of Sclerotinia sclerotiorum, were tested for their antagonism to sclerotia of the closely related pathogen, Ciborinia camelliae. Treatment of sclerotia in sterile sand or potting‐mix assays with isolate suspensions of 106 or 107 spores/ml had little effect on the viability of sclerotia, 12–37 weeks after treatment. In a field trial, spore suspensions of T. virens LU556, C. rosea LU155, and C. minitans LU1 12, sprayed in July, August, and September, at a total of 0.8–2.9 × 1011 spores/m2 onto soil naturally infested with over 600 sclerotia/m2, had no effect on apothecial production or on sclerotial numbers recovered at the end of the trial, 8 weeks after the last mycoparasite application. Parasitism of sclerotia by C. minitans, C. rosea, and T. virens was not observed under scanning electron microscopy examination. Thus, the test isolates were not considered effective parasites of C. camelliae sclerotia. Subsequently, 376 microorganisms isolated from C. camelliae sclerotia baits that had been buried in soil, and 30 microorganisms from decaying C. camelliae sclerotia, were screened in vitro for their ability to parasitise healthy sclerotia of the pathogen. The most effective antagonists were T. virens LU569 and T. viride LU570, which reduced numbers of viable C. camelliae sclerotia after 14 weeks by 53% and 43%, respectively. These isolates warrant further evaluation under field conditions where one can potentially manipulate the soil environment by the addition of soil conditioners to enhance their efficacy in situ.

Change in the Properties of High-Strength Fibres under the Effect of Soil Microorganisms

The resistance of high-strength para-aramid and polyethylene terephthalate fibres to soil microorganisms was investigated. It was found that the curve of the fibre strength versus the duration of exposure to soil microflora is monotonically diminishing. The elongation at break of the fibres also changes monotonically, with the exception of Kevlar. The change in the strength and elongation at break as a function of the duration of exposure in the soil is approximated by exponential equations can be used to predict the change in these indexes. The values of the coefficients in the equation are found. A comparison of the features of the change in the mechanical characteristics with the features of the molecular and supramolecular structure allows assessing the role of both the plasticizing effect of water and microbiological degradation. The increase in the deformation characteristics with a simultaneous decrease in the strength of para-aramid fibres, especially SVM, can probably be attributed to the effect of plasticization and the lability of their structure under the effect of moisture.

Mycorrhizosphere interactions to improve plant fitness and soil quality.

Arbuscular mycoruhizal fungi are key components of soil microbiota and obviously interact with other microorganisms in the rhizosphere, i.e. the zone of influence of plant roots on microbial populations and other soil constituents. Mycorrhiza formation changes several aspects of plant physiology and some nutritional and physical properties of the rhizospheric soil. These effects modify the colonization patterns of the root or mycovrhizas (mycorrhizosphere) by soil microorganisms. The rhizosphere of mycorrhizal plants, in practice a mycorrhizosphere, harbors a great array of microbial activities responsible for several key ecosystem processes. This paper summarizes the main conceptual principles and accepted statements on the microbial interactions between mycorrhizal fungi and other members of rhizosphere microbiota and discusses current developments and future trends concerning the following topics: (i) effect of soil microorganisms on mycorrhiza formation; (ii) mycorrhizosphere establishment; (iii) interactions involved in nutrient cycling and plant growth; (iv) interactions involved in the biological control of plant pathogens; and (v) interactions to improve soil quality. The main conclusion is that microbial interactions in the rhizosphere of mycorrhizal plants improve plant fitness and soil quality, critical issues for a sustainable agricultural development and ecosystem functioning.

Effect of indigenous arbuscular mycorrhizal endophytes on the development of six wild plants colonizing a semi-arid area in south-east Spain.

The effect of arbuscular mycorrhizal fungi (AMF) an six plant species that frequently grow in areas of Mediterranean climate in south-east Spain was studied. In semi-arid soils, the most abundant AMF was Glomus aggregation Schenck and Smith, followed by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe. The vascular plant species studied were Dittrichia viscosa (L.) W. Greuter (Asteraceae); Dactylis glomerata L., Piptatherum miliaceum (L.) Cosson, and Slipa tenacissima L. (Poaceae); Retama sphaerocarpa (L.) Boiss., and Ulex parviflorus Pourret (Fabaceae). Legumes were studied with single and dual symbiosis (Rhizobium and AMF). In a greenhouse experiment, inoculated plants developed better than noninoculared controls, as shown by dry weight and tissue N and P content. Plants inoculated with G. aggregation grew better than plants inoculated with G. mosseae. For this reason G. aggregatum was chosen for a field experiment, in which this AM fungus increased shoot dry mass, shoot length, and percent survival after transplantation. The effects of soil microorganisms on development, survival and fertility of native plants, their influence on the effects of the erosion, and their importance in plant repopulation programmes are discussed.

The Rhizobium strain-dependent efficiency of the plant infection dilution frequency technique, as encountered for pigeon pea

Soil samples were inoculated with different levels (101 to 107 cells g-1 soil) of A7 and RM7 (a streptomycin-resistant mutant of A7) strains of pigeon pea Rhizobium. The populations of applied rhizobia in soil were immediately investigated with the plant infection dilution frequency technique (PIT). The results showed that PIT failed to detect the population up to the level of 4.1×103 cells of A7 strain g-1 soil, whereas it started to detect the RM7 population when applied at 3.4×103 cells g-1 soil. Keeping the skips negative, the PIT detected 5.8×101 and 1.0×103 cells out of the applied 4.1×105 and 4.1×107 cells of A7 g-1 soil, respectively, whereas 1.7×101, 1.0×103 and 5.8×104 cells of RM7 were detectable out of the applied 3.4×103, 3.4×105 and 3.4×107 cells g-1 soil, respectively. These results indicate that the method counts the population of the RM7 strain more efficiently than that of the A7 strain when equal numbers of cells of these strains are added to the soil. This variation in efficiency was ascribed to the variable antagonistic effect of soil microorganisms on the Rhizobium.

Effects of soil microorganisms on mycorrhizal contribution to growth of big bluestem grass in non-sterile soil

Plant dry weight and mycorrhizal root colonization of big bluestem ( Andropogon gerardii Vitman) inoculated with Glomus etunicatum Becker and Gerd. were suppressed if non-sterile prairie soil sievings or filtrate were added to pasteurized soil. Addition of prairie soil microorganisms, isolated onto peptone yeast extract, King's B, or starch casein agar media, to pasteurized soil also reduced dry weight and mycorrhizal root colonization of big bluestem inoculated with G. etunicatum. In contrast, addition of non-sterile soil sievings or filtrate or organisms isolated onto potato dextrose or pseudomonas isolation agar to pasteurized soil improved growth of non-mycorrhizal big bluestem. These effects of soil micro-organisms on plant growth were further quantified by comparing 32P uptake by fungicide treated and untreated mycorrhizal plants and by non-mycorrhizal plants in pasteurized and non-sterile soil. Mycorrhizal plants grown in pasteurized soil absorbed ≅10 times more 32P than mycorrhizal plants grown in non-sterile soil. Application of propiconazole (Tilt) or fenarimol (Rubigan), fungicides which inhibit 32P uptake by mycorrhizas, resulted in approx. 40- and 5-fold reductions in 32P uptake in pasteurized and non-sterile soil, respectively. Thus, more 32P is absorbed in pasteurized than in non-sterile soil, probably because soil microorganisms limit mycorrhizal activity in non-sterile soil. Assessments of mycorrhizal contribution to plant growth conducted in sterilized soils may significantly overestimate the effects of VAM fungi because other soil microorganisms are not considered.

Effect of soil micro-organisms on spore germination and growth of the vesicular-arbuscular mycorrhizal fungus Glomus mosseae

Germination rate of surface-sterilized chlamydospores of the vesicular-arbuscular (VA) mycorrhizal endophyte Glomus mosseae was significantly hastened by the presence of freeliving fungi in a time-course experiment on water-agar. The fungi also stimulated hyphal growth, while vegetative spores formed only on the mycelium arising from resting spores grown in the presence of such free-living micro-organisms. The time of appearance of vegetative spores was related to the time when the free-living fungi were added. The interest in soil biology and ecology of these microbe-microbe relationships involving VA fungi is discussed.

Effects of soil microorganisms on the release of bound carbon-14 residues from soils previously treated with [14C]parathion

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of soil microorganisms on the release of bound carbon-14 residues from soils previously treated with [14C]parathionKenneth D. Racke and E. Paul LichtensteinCite this: J. Agric. Food Chem. 1985, 33, 5, 938–943Publication Date (Print):September 1, 1985Publication History Published online1 May 2002Published inissue 1 September 1985https://doi.org/10.1021/jf00065a041RIGHTS & PERMISSIONSArticle Views82Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (846 KB) Get e-Alerts Get e-Alerts

Effect of soil micro-organisms on formation of vesicular-arbuscular mycorrhizas

Common soil micro-organisms facilitate mycorrhizal formation by Glomus mosseae and Medicago sativa. The effect can be accounted for, at least in part, by an improvement of the independent hyphal growth at the pre-infection stages.