Soil Fungal Biomass Research Articles

Soil organic matter, nutrient distribution, fungal and microbial biomass and enzyme activities in a forest beech stand on the Apennines of southern Italy

The aim of this study was to analyse the amount and qualitative characteristics of organic matter (OM) in the litter horizon (considering leaf litter at different decomposition stages) and underlying soil to a 30-cm depth in a beech stand on the Apennines in southern Italy. Distribution of major nutrients as well as fungal and microbial biomass were also evaluated, in addition to beech leaf nutrient content monitor from full expansion to abscission in order to estimate annual nutrient input to soil from litterfall and nutrient retranslocation before abscission. OM was significantly higher in leaf litter. C/N ratio and the Na, Mn, Fe levels also decreased along the decomposition continuum, whereas N and S contents slowly decreased with soil depth. Generally, leaf nutrient content was also significantly lower in dead leaves, indicating efficient retranslocation to persistent organs. Fungal biomass was the highest in leaf layers, with no significant changes between spring and autumn samplings. Enzyme activities did not differ significantly along the decomposition continuum but marked decreases were found in the upper soil layer; these remained relatively constant, with the exception of laccase, at deeper soil depths. No seasonal effect on enzyme activities and OM content was found.

Effects of nitrogen and phosphorus addition on soil microbial community in a secondary tropical forest of China

Nutrient availability greatly regulates soil microbial processes and functions in tropical forests. However, few studies have explored the impacts of nitrogen (N) addition (100 kg P ha−1 year−1), phosphorus (P) addition (100 kg N ha−1 year−1), and N × P interaction on soil microbial biomass and microbial community composition in tropical forests. We established a field nutrient manipulation experiment in a secondary tropical forest of South China. Soil physicochemical properties and microbial community composition were measured. Analysis of phospholipid fatty acids (PLFAs) was used to determine soil microbial biomass and composition, and both were related to environmental factors by the redundancy analysis (RDA) and principal response curves (PRC). We demonstrated that N addition usually did not affect microbial biomass, which was increased by P addition over 3 years of fertilization. Nitrogen addition decreased soil bacterial biomass but did not affect soil fungal biomass after 3 years of fertilization. After P addition, soil fungal biomass increased faster than soil bacterial biomass, indicating a more sensitive response of soil fungi to P addition than bacteria. Phosphorus addition increased fungi/bacteria ratio (F/B) ratios after 3 years of fertilization. Both N and P additions had different effects on soil microbial community in this tropical forest and, thus, probably altered ecosystem functioning.

English

Today, Brazil is the second major soybean (Glycine max (L.) producer of the world; however, few studies on the effects of transgenesis in the soil microbiota are completed. This study aims at assessing the residual effect of a transgenic soybean with tolerance to the imidazolinone herbicide group on the soil microbiota. The parameters examined were: the soil basal respiration, microbial biomass carbon (MBC) of the soil, metabolic quotient, spores of arbuscular mycorrhizal fungi and total soil fungal and bacterial biomass using epifluorescence technique in areas with eight years of no-tillage cultivated with non-transgenic (BRS133) and transgenic (BRS245) soybeans, in Londrina and Ponta Grossa - PR, Brazil, in the 2011/2012 growing season. The experiment was conducted in a randomized block design and each treatment with six replications. Results showed a significant increase on the MBC in Londrina soils with the BRS245 soybean, and also a significant increase in the total bacterial biomass in the both Londrina and the Ponta Grossa soil with BRS245 soybean, in contrast to those cultivated with BRS133. The BRS245 transgenic soybean crop changed the soil microbiota mainly by increasing the bacterial biomass, which was estimated by the epifluorescence microscopy method. The epifluorescence technique can be used to estimate soil biomass by fungi and bacteria with success.   Key words: Epifluorescence microscopy method, Glycine max, soil bacterial and fungal biomass.

An optimized HPLC method for soil fungal biomass determination and its application to a detritus manipulation study

The goal of this research was to develop modified analytical method for the quantitative analysis of ergosterol, which is highly effective marker for fungal biomass. We suggest that our optimized method for the determination of ergosterol is an effective way to monitor changes in fungal biomass under different environmental conditions.

Soil fungal and bacterial biomass determined by epifluorescence microscopy and mycorrhizal spore density in different sugarcane managements

Crop productivity and sustainability have often been related to soil organic matter and soil microbial biomass, especially because of their role in soil nutrient cycling. This study aimed at measuring fungal and bacterial biomass by epifluorescence microscopy and arbuscular mycorrhizal fungal (AMF) spore density in sugarcane (Saccharum officinarum L.) fields under different managements. We collected soil samples of sugarcane fields managed with or without burning, with or without mechanized harvest, with or without application of vinasse and from nearby riparian native forest. The soil samples were collected at 10cm depth and storage at 4°C until analysis. Fungal biomass varied from 25 to 37µg C g-1 dry soil and bacterial from 178 to 263µg C g-1 dry soil. The average fungal/bacterial ratio of fields was 0.14. The AMF spore density varied from 9 to 13 spores g-1 dry soil. The different sugarcane managements did not affect AMF spore density. In general, there were no significant changes of microbial biomass with crop management and riparian forest. However, the sum of fungal and bacterial biomass measured by epifluorescence microscopy (i.e. 208-301µg C g-1 dry soil) was very close to values of total soil microbial biomass observed in other studies with traditional techniques (e.g. fumigation-extraction). Therefore, determination of fungal/bacterial ratios by epifluorescence microscopy, associated with other parameters, appears to be a promising methodology to understand microbial functionality and nutrient cycling under different soil and crop managements.

Patterns and drivers of soil microbial communities along a precipitation gradient on the Mongolian Plateau

Our understanding of the patterns and drivers of soil microbial communities at the regional scale remains inadequate although both have been extensively studied in plant communities. In this study, we examined the patterns and drivers of soil microbial communities using data from 24 arid and semi-arid ecosystem sites, covering a broad range of community types, soils, and climates on the Mongolian Plateau. Our findings demonstrated that, at the regional scale, the total soil microbial biomass, fungal biomass, bacterial biomass, and actinomycete biomass increased with mean annual precipitation, soil organic carbon (SOC), total soil nitrogen (TSN), C:N ratio, annual aboveground net primary productivity (ANPP), and root biomass. However, these values decreased with increasing soil pH and mean annual temperature and showed hump-shaped relationships with plant species richness (SR) and ANPP. Variations in soil microbial communities were associated with precipitation, plant community (SR, ANPP, and BB), and soil properties (SOC, TSN, and pH). At the local scale in a typical steppe, water addition by 30 % increased the total microbial biomass by 20 %, bacterial biomass by 16 %, and actinomycete biomass by 54 %. The increased microbial biomass, however, was still 25–41 % lower than that in the meadow steppe that received similar amount rainfall, indicating that, apart from the dominant effect of precipitation, plant community and soil properties could also regulate soil microbial communities. Our findings have important implications for understanding the impacts of climate change (e.g., precipitation) on soil microbial communities and linkages to ecosystem functioning in the Inner Mongolia grasslands and elsewhere.

Effects of addition of nitrogen on soil fungal and bacterial biomass and carbon utilisation efficiency in a city lawn soil

The aim of this study was to investigate the effects of nitrogen (N) addition on soil microbial (fungal and bacterial) biomass and carbon utilisation efficiency (CUE) in a city lawn soil. A field experiment was conducted with three N treatments (kg N ha–1 year–1): the control (0), low-N (100), and high-N (200). Soil biogeochemical properties including pH, C : N, CUE, microbial biomass C (MBC), fungal and bacterial biomass, microbial C uptake rates, and soil respiration (SR) rates were determined during a 500-day experiment. The low- and high-N treatments significantly decreased soil pH, MBC, and CUE. Available N and soil acidification caused a decline in soil MBC. Soil acidification was not beneficial for microbial biomass growth, especially for bacteria. The treatments with N changed soil biomass from bacterial-dominant to fungal-dominant. The results also showed that the CUE of bacterial-dominant soil was higher than that of fungal-dominant soil, which is contrary to previous studies. However, SR did not increase with decreased CUE under N treatments, because the addition of N limited soil microbial C uptake rates and significantly decreased soil microbial biomass. The CUE showed a negative correlation with soil temperature for the control treatment but not for the N treatments, which suggested that added N played a more important role in CUE than did soil temperature. Our results showed that addition of further N significantly alters soil biogeochemical properties, alters the ratio of bacteria to fungi, and decreases microbial carbon utilisation, which should provide important information for model-based prediction of soil C-cycling.

Species-dependent responses of soil microbial properties to fresh leaf inputs in a subtropical forest soil in South China

Aims Forest disturbance from extreme weather events due to climate change could increase the contribution of fresh green leaves to the litter layer of soil and subsequently alter the composition and activity of the soil microbial properties and soil carbon cycling. The objective of this study was to compare the effect of naturally fallen litter and fresh leaves on the soil microbial community composition and their activities. Methods Fresh leaves and normal fallen litter were collected from four tree species (Pinus elliottii, Schima superba, Acacia mangium, A. auricu- laeformis) in subtropical China and mixed with soil. Soil microbial community composition was determined using PLFAs, and its activ- ity was quantified by soil respiration. During a 12-month period, the decomposition rate of litter was measured bimonthly using a litterbag method. Soil microbial samples were collected after 6 and 12 months. Soil respiration was measured monthly. Important Findings We found that fresh leaves decomposed faster than their conspe- cific fallen litter. Although total microbial biomass and bacterial biomass were similar among treatments, soil fungal biomass was higher in fresh leaf than fallen litter treatments, resulting in greater values of the Fungal phospholipid fatty acids (PLFAs)/ Bacterial PLFAs ratio. Fungal PLFA values were greater for Schima superba than the other species. The effect of litter type on soil respiration was species-dependent. Specifically, fallen litter released 35% more CO2 than fresh leaves of the conifer P. elliottii. The opposite pattern was observed in the broadleaf species whose fresh leaf treatments emitted 17-32% more CO 2 than fallen litter. Given future predictions that global climate change will cause more disturbances to forests, these results indicate that conifer and broadleaf forests in subtropical China may respond differently to increased fresh litter inputs, with net soil microbial respiration decreasing in conifer forests and increasing in broadleaf forests.

Soil microbial properties under different vegetation types on Mountain Han

This study investigated the influence of broadleaf and conifer vegetation on soil microbial communities in a distinct vertical distribution belt in Northeast China. Soil samples were taken at 0-5, 5-10 and 10-20 cm depths from four vegetation types at different altitudes, which were characterized by poplar (Populus davidiana) (1250-1300 m), poplar (P. davidiana) mixed with birch (Betula platyphylla) (1370-1550 m), birch (B. platyphylla) (1550-1720 m), and larch (Larix principis-rupprechtii) (1840-1890 m). Microbial biomass and community structure were determined using the fumigation-extraction method and phospholipid fatty acid (PLFA) analysis, and soil fungal community level physiological profiles (CLPP) were characterized using Biolog FF Microplates. It was found that soil properties, especially soil organic carbon and water content, contributed significantly to the variations in soil microbes. With increasing soil depth, the soil microbial biomass, fungal biomass, and fungal catabolic ability diminished; however, the ratio of fungi to bacteria increased. The fungal ratio was higher under larch forests compared to that under poplar, birch, and their mixed forests, although the soil microbial biomass was lower. The direct contribution of vegetation types to the soil microbial community variation was 12%. If the indirect contribution through soil organic carbon was included, variations in the vegetation type had substantial influences on soil microbial composition and diversity.

Effects of disturbance scale on soil microbial communities in the Western Cascades of Oregon

To gain a better understanding of how rapidly microbial communities respond to different magnitudes of perturbation that mimic minor or catastrophic disturbances. Two montane sites in the western Cascade Mountains of Oregon with adjacent areas of forest and meadow vegetation were studied. A reciprocal transplant experiment evaluated both minor (soil cores remaining in the same vegetation type) or more severe disturbance (soil cores transferred to a different vegetation type). The biomass and composition of the bacterial and fungal communities were measured for 2 years following the establishment of the experiment. Minor disturbance (coring) had little impact on microbial biomass but transferring between vegetation type showed greater fungal biomass in soil incubated in the forest environment. The composition of bacterial communities was not influenced by coring but responded strongly to transfers between vegetation sites, changing to reflect their new environment after 2 years. Fungal community composition responded somewhat to coring, probably from disrupting mycorrhizal fungal hyphae, but more strongly to being transferred to a new environment. The response of the microbial community to major disturbance was rapid, showing shifts reflective of their new environment within 2 years, suggesting that microbial communities have the capacity to quickly adjust to catastrophic disturbances.

High Polyacrylamide Application Rates Do Not Affect Eubacterial Structural Diversity

Anionic polyacrylamide (PAM) is a linear, water-soluble anionic polymer that is widely used for erosion control and water quality protection. There has been an issue whether this formulation could possibly have negative effects on soil microbial diversity by altering microbial binding to soil particles or to one another and thus restricting their mobility and role in carbon and nutrient cycling. We conducted an 8-year study annually applying ultra-high rates of PAM to soil and then monitored impacts on soil bacterial diversity. In July and August, we measured active soil bacterial and fungal biomass and microbial diversity in soils receiving 0 (control), 2,691, and 5,382 kg active ingredient PAM ha−1. Active microbial biomass in soil was 19–33 % greater in the untreated control than soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1. Active bacterial biomass in soil was 21–31 % greater in the control treatment than in soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1 in August, but not July. Active fungal biomass in soils was 38–50 % greater in the control treatment than soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1 in July, but not August. Molecular methods were used to access the bacterial diversity, richness, and evenness in an agricultural soil that received 0 (control), 2,691, and 5,382 kg of active ingredient PAM ha−1. We found that although soil receiving these massive PAM application rates and prolonged exposure may reduce active bacterial and fungal biomass, PAM application did not substantially or consistently affect bacterial structural diversity, richness, or evenness in this agricultural soil.

Cross-Site Soil Microbial Communities under Tillage Regimes: Fungistasis and Microbial Biomarkers

The exploitation of soil ecosystem services by agricultural management strategies requires knowledge of microbial communities in different management regimes. Crop cover by no-till management protects the soil surface, reducing the risk of erosion and nutrient leaching, but might increase straw residue-borne and soilborne plant-pathogenic fungi. A cross-site study of soil microbial communities and Fusarium fungistasis was conducted on six long-term agricultural fields with no-till and moldboard-plowed treatments. Microbial communities were studied at the topsoil surface (0 to 5 cm) and bottom (10 to 20 cm) by general bacterial and actinobacterial terminal restriction fragment length polymorphism (T-RFLP) and phospholipid fatty acid (PLFA) analyses. Fusarium culmorum soil fungistasis describing soil receptivity to plant-pathogenic fungi was explored by using the surface layer method. Soil depth had a significant impact on general bacterial as well as actinobacterial communities and PLFA profiles in no-till treatment, with a clear spatial distinction of communities (P < 0.05), whereas the depth-related separation of microbial communities was not observed in plowed fields. The fungal biomass was higher in no-till surface soil than in plowed soil (P < 0.07). Soil total microbial biomass and fungal biomass correlated with fungistasis (P < 0.02 for the sum of PLFAs; P < 0.001 for PLFA 18:2ω6). Our cross-site study demonstrated that agricultural management strategies can have a major impact on soil microbial community structures, indicating that it is possible to influence the soil processes with management decisions. The interactions between plant-pathogenic fungi and soil microbial communities are multifaceted, and a high level of fungistasis could be linked to the high microbial biomass in soil but not to the specific management strategy.

Responses of the extracellular enzyme activities in hardwood forest to soil temperature and seasonality and the potential effects of climate change

The activities of extracellular enzymes that participate in the decomposition of litter and organic matter in forest soils depend on, among other factors, temperature and soil moisture content and also reflect the quality of litter, which changes dramatically after a short litterfall period. Here, we explored the effects of soil temperature and seasonality on the sizes of extracellular enzyme pools and activities in a temperate hardwood forest soil with dominant Quercus petraea (cambisol, mean annual temperature 9.3 °C). We hypothesized that the most significant variation of enzyme activity would occur in the litter, which faces greater variations in temperature, moisture content and chemical quality during the season, which decrease with soil depth. The site exhibited relatively large seasonal temperature differences and moderate changes in soil moisture content. Enzyme activity, microbial biomass, soil moisture content, temperature and pH were monitored for three years in the litter (L), organic horizon (O) and upper mineral horizon (Ah). Enzyme activity in vitro strongly increased with temperature until 20–25 °C, the highest temperatures recorded in situ. While no significant differences in the pools of most extracellular enzymes and in the content of microbial biomass were found among the seasons, enzyme activity typically increased during the warm period of the year, especially in the O and Ah horizons. Approximately 63%, 64%, and 69% of total annual activity was recorded during the warm period of the year in the L, O, and Ah horizons, respectively. Significant positive correlations were observed between soil moisture content and fungal biomass, but not bacterial biomass, indicating a decrease of the fungal/bacterial biomass ratio under dry conditions. The effect of moisture on enzyme activities was not significant except for endoxylanase in the litter. If soil temperature rises as predicted due to global climate change, enzyme activity is predicted to rise substantially in this ecosystem, especially in winter, when decomposition is not limited by drought and fresh litter that can decompose rapidly is present.

Bioindication potential of using molecular characterisation of the nematode community: Response to soil tillage

The utility of a high-throughput molecular characterisation (directed - terminal restriction fragment length polymorphism – dTRFLP) of soil nematode community structure was evaluated in a field trial of the effects of tillage intensity. Replicated plots were established in a field previously used for continuous, conventional tillage of spring barley (Hordeum vulgare) and cultivated by: zero tillage; minimum tillage; conventional tillage; deep tillage and conventional tillage with compaction. Nematodes were sampled in spring, summer and autumn for three years after treatment began. Total nematode abundance and Nematode Channel Ratio indicated changes due to the zero and minimum tillage, more nematodes and a greater proportion of fungal feeders, but effects were secondary to those of year and season. The effects of tillage were far easier to interpret when other bioindicators were also taken into account. Increases in soil carbon and fungal biomass in the upper layers of the zero and minimum tillage treatments, observed in parallel studies, corroborated the nematode data. The high-throughput molecular method proved to be well suited for multiple measurements of nematode community structure, although limitations in the resolution of nematode taxa could obscure changes in generic and species composition.

ISTA 14—Impact of antibiotics from pig slurry on soil microbial communities, including the basidiomycete Trametes versicolor

Livestock slurry containing antibiotics is a source of contamination of agricultural soils, with possible effects on soil function and micro-organisms. Extracellular oxido-reductases and hydrolases from the fungus T. versicolor and fungal growth were monitored in liquid cultures in the presence of tetracycline, lincomycine, sulfadiazine and ciprofloxacin for 10 days, in order to assess the suitability of these enzymes as biomarkers. Among the conditions of treatment, statistical analysis demonstrated an increase in manganese-dependent peroxidase after exposure to sulfadiazine at 1 mg/L when compared with the control. Acid phosphatase activity was decreased by lincomycine at 1 or 10 mg/L. Conversely, β-glucosidase activity increased in the presence of this antibiotic at 10 mg/L. In Terrestrial Model Ecosystems spiked with contaminated pig slurry, lincomycine at the concentration of 8 or 80 μg/kg dry soil, and ciprofloxacin at 250 ng/kg dry soil decreased the activity of soil dehydrogenase, when compared with a green slurry treatment, over 28-day incubations. Laccase activity was similarly decreased in the presence of the highest concentration of antibiotics. We determined bacterial and fungal biomasses using Q-PCR. Bacterial biomass was increased in the presence of lincomycine at 80 μg/kg whatever the time of exposure, and to a lesser extent in the presence of ciprofloxacin at 250 ng/kg, but only at day 28. In contrast, both antibiotics, whatever their concentrations, did not modify fungal biomass in soil. In conclusion, we were unable to demonstrate important effects of antibiotics at concentrations found in the agricultural environment.

Soil disturbance alters plant community composition and decreases mycorrhizal carbon allocation in a sandy grassland

We have studied how disturbance by ploughing and rotavation affects the carbon (C) flow to arbuscular mycorrhizal (AM) fungi in a dry, semi-natural grassland. AM fungal biomass was estimated using the indicator neutral lipid fatty acid (NLFA) 16:1ω5, and saprotrophic fungal biomass using NLFA 18:2ω6,9. We labeled vegetation plots with (13)CO(2) and studied the C flow to the signature fatty acids as well as uptake and allocation in plants. We found that AM fungal biomass in roots and soil decreased with disturbance, while saprotrophic fungal biomass in soil was not influenced by disturbance. Rotavation decreased the (13)C enrichment in NLFA 16:1ω5 in soil, but (13)C enrichment in the AM fungal indicator NLFA 16:1ω5 in roots or soil was not influenced by any other disturbance. In roots, (13)C enrichment was consistently higher in NLFA 16:1ω5 than in crude root material. Grasses (mainly Festuca brevipila) decreased as a result of disturbance, while non-mycorrhizal annual forbs increased. This decreases the potential for mycorrhizal C sequestration and may have been the main reason for the reduced mycorrhizal C allocation found in disturbed plots. Disturbance decreased the soil ammonium content but did not change the pH, nitrate or phosphate availability. The overall effect of disturbance on C allocation was that more of the C in AM fungal mycelium was directed to the external phase. Furthermore, the functional identity of the plants seemed to play a minor role in the C cycle as no differences were seen between different groups, although annuals contained less AM fungi than the other groups.

Tillage-induced changes in fungal and bacterial biomass associated with soil aggregates: A long-term field study in a subtropical rice soil in China

The composition and function of the soil microbial community can be strongly influenced by soil structure and tillage. Soil total microbial biomass C (MBC), microbial biomass N (MBN), and fungal and bacterial biomass associated with different soil aggregate-size fractions were measured for a long-term no-till subtropical rice soil ecosystem to determine how tillage shifts microbial community structure and to detect the spatial scale at which microorganisms are the most sensitive to disturbance. Surface soil (0–20cm) was fractionated into aggregate-sizes (>4.76mm, 4.76–2.0mm, 2.0–1.0mm, 1.0–0.25mm, 0.25–0.053mm, <0.053mm) under three tillage regimes. Soil MBC, MBN, fungal biomass and bacterial biomass were significantly higher under no tillage (NT) than conventional tillage (CT) and CT flooded paddy field (FPF) in whole soil (p<0.05). Microbial biomass C, N and fungal biomass were significantly higher under NT than CT and FPF for all aggregate sizes. No significant tillage effects on microbial biomass C:N ratio were observed, but analysis of soil aggregates revealed significant differences due to tillage. Microbial biomass C:N ratio averaged 8.8, 8.5, and 8.4 for CT, NT, and FPF, respectively, while the ratio was significantly higher under CT than NT for macroaggregates >1.0mm, indicating a tillage-induced N limitation in macroaggregates. The fungal:bacterial biomass ratio ranged from 0.5 to 4.5, and was highest in 4.76–2mm aggregates for all tillage regimes. Fungal:bacterial ratios were significantly higher for aggregate sizes >1.0mm (2.4) than for <1.0mm aggregates (0.7). Tillage effects on fungal over bacterial dominance were not significant for whole soil and most aggregate sizes. The NT regime increased microbial biomass, but this increase was proportional for both bacteria and fungi. The soil microbial biomass and community structure was likely controlled by particle size at the aggregate-scale (0.05–5.0mm), while tillage played a role in regulating the microbial community structure.

Impact of endochitinase-transformed white spruce on soil fungal communities under greenhouse conditions

Chitinase genes isolated from plants, bacteria or fungi have been widely used in genetic engineering to enhance the resistance of crops and trees to fungal pathogens. However, there are concerns about the possible effect of chitinase-transformed plants on nontarget fungi. This study aimed at evaluating the impact of endochitinase-transformed white spruce on soil fungal communities. Endochitinase-expressing white spruce and untransformed controls were transplanted in soils from two natural forests and grown for 8 months in a greenhouse. Soil fungal biomass and diversity, estimated through species richness and Shannon and Rao diversity indices, were not different between transgenic and control tree rhizospheres. The fungal phylogenetic community structure was the same in soil samples from control and transgenic white spruces after 8 months. Soil type and presence of seedlings had a much more significant impact on fungal community structure than the insertion and expression of the ech42 transgene within the white spruce genome. The results suggest that the insertion and constitutive expression of the ech42 gene in white spruce did not significantly affect soil fungal biomass, diversity and community structure.

Simulated mammal browsing and host gender effects on dual mycorrhizal Salix repens

We studied effects of simulated browsing and host plant gender on mycorrhizal status of dioecious Salix repens, forming both ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) symbioses. Owing to their lower biomass production, AM fungi may require less carbon from the host and have a competitive advantage over ECM fungi when carbon availability is reduced. Further, in dioecious plants, females have generally higher reproduction costs than males. Hence, herbivory may be especially detrimental to female plants and their ECM symbionts in favour of AM symbionts. Fifty percent shoot clipping increased the number of vegetative shoots but reduced the proportion of flowering shoots equally in male and female hosts. Despite clipping, ECM and AM colonization remained unchanged. However, slightly reduced soil fungal biomass was found in clipped patches of male S. repens. Our novel finding of AM spores occurring in the ECM fungal mantle of S. repens roots suggests that both mycorrhizal partners may coexist in the same root segment. Since no interaction between gender and clipping in fungal parameters was detected, we conclude that female and male S. repens are equally preferable hosts for fungal symbionts, even when carbohydrate availability has been decreased because of herbivory.

Changes in nutrient content, enzymatic activities and microbial properties of lateritic soil due to application of different vermicomposts: a comparative study of ergosterol and chitin to determine fungal biomass in soil

In this experiment, vermicomposts, prepared from five different waste materials, were applied to acid lateritic soil under field conditions and soil samples were collected after 90 days to study the effect of vermicomposts on different chemical and biochemical. Results suggest that vermicompost prepared from paddy straw is most effective to improve nutrient content, enzymatic activities and microbial properties of lateritic soil. Vermicompost application significantly (P ≤ 0.05) increased the concentration of organic C, mineralizable N, available P and exchangeable K in soil. Amylase, protease, urease and acid phosphatase activities were also significantly (P ≤ 0.05) higher in vermicompost treated soils compared with the control. Both basal and substrate-induced microbial respiration, microbial biomass C and N and fungal population in lateritic soil were increased due to vermicompost application. Ergosterol and chitin content were significantly (P ≤ 0.05) higher in vermicompost treated soils over the control. Application of vermicompost increased the proportion of fungal biomass in total soil microorganisms.