Arbuscular Mycorrhizal Spore Numbers Research Articles

Effect of arbuscular mycorrhizal fungi inoculation on revegetation at Nukui Dam site, Japan

The establishment of the surviving arbuscular mycorrhizal (AM) fungi, Gigaspora margarita Becker & Hall, inoculated in revegetation at the Nukui Dam was studied. The population of AM fungi and AM colonization of three plant species Japanese hill cherry (Prunus jamasakura Sieb. ex Koidz, yamazakura-inoculated plant), eulalia (Miscanthus sinensis Anderss, susuki), and mugwort (Artemisia vulgaris Pampan, yomogi) were investigated to compare inoculated and non-inoculated treatments. The AM colonisation was enhanced in inoculated plots although natural or accidental AM fungi were involved in non-inoculated plots and successfully colonised. Coverage of soil surface was more than 80% and even reached nearly 100% in summer regardless of the soil amendment type.The number of spores and the percentage of colonisation of investigated plant roots, as well as the density of typical AM structures such as arbuscules, auxiliary cells, vesicles, and coiling hyphae by AM fungi in inoculated plots were higher than those in non-inoculated ones. Some spores were Gigaspora andGlomus-inoculated species and were relatively rich in inoculated plots of Yamazakura. There was a significant increase in the number of AM spores in inoculated treatments at a 5% confidence level (ANOVA, p<0.05) in Susuki and Yamazakura. Much more spores of Gigaspora sp.occurred in the rhizosphere soil of Yamazakura and Susuki plants in inoculated plots than in non-inoculated plots (2.33 and 3.73 times, respectively).The colonisation intensity and spore number in the rhizosphere were positively correlated. Therefore, inoculation at an early establishment should be important for the successive development of AM-plant symbiosis formation.

Fertilization integrated with microbial inoculants improves bell pepper production

ABSTRACT Increased use of fertilizers under intensive agriculture has the possibility of environmental contamination. The use of microbial inoculants may be effective in sustaining crop productivity, soil health, and supplementing chemical fertilizers. The investigation evaluated responses of arbuscular mycorrhizal (AM) fungi, Glomus mosseae (G) and Acaulospora laevis (A) and the bacterium Pseudomonas fluorescens (Pf) on bell pepper (Capsicum annuum L.) when provided superphosphate at F1 = 60 kg ha−1 (0.45 g/pot), F2 = 120 kg ha−1 (0.90 g/pot), or F3 = 240 kg ha−1 (1.80 g/pot). Plant growth, nutrient content, and yield 120 days after transplanting (DAT) were determined. Plants responded best to F1 followed by F2, while F3 produced inhibitory effects. The highest AM colonization and spore numbers were with G + A+ Pf, resulting in an increase in chlorophyll content, root phosphatase activity, shoot fresh weight, early fruit formation, number of fruit/plant, fruit size, weight, and early ripening. Inoculation with G. mosseae alone increased leaf area, photosynthesis, plant height, root freshness and dry weight. The G+ Pf commonly produced highest shoot fresh weight and fruit nutrient content. The effectiveness of these inoculants on bell pepper growth and yield was highest; 60 and 120 kg ha−1 P-fertilizer level when amended with G + A+ Pf. Use of AM or micro-inoculants may reduce fertilizer input and enhance nutrient utilization efficiency, which positively affected qualitative characteristics, nutrient uptake, and resistance to suboptimal conditions, but has few or little effect on quantitative characteristics. More work is needed to determine optimum rates of the materials tested to produce marketable size fruit.

Soil properties and climate affect arbuscular mycorrhizal fungi and soil microbial communities in Mediterranean rainfed cereal cropping systems

Soil microorganisms are generally considered sensitive indicators of soil health and fertility. Understanding the role of environmental factors in driving soil microorganisms’ distributions is vital for sustainable crop production, particularly in vulnerable agricultural systems. This study aims to investigate the effect of environmental factors on the variation of soil microbial biomass and arbuscular mycorrhizal (AM) fungi in Mediterranean rainfed cereal systems. To do so, plant roots and soil were sampled from three cereal crops: Avena sativa L., Hordeum vulgare L. and Triticum turgidum L. growing in 24 rainfed sites from three different bioclimatic zones (sub-humid, superior semi-arid and middle semi-arid) in northern Tunisia. Soil microbial phospholipid fatty acids (PLFA) fingerprints, percentage of root length colonized by AM fungi as well as AM fungal spore density were then assessed. The redundancy analysis (RDA) revealed that soil organic matter (SOM), temperature, altitude and soil sand content accounted for 22.7 % of the variation of the microbial PLFA profiles used to estimate both soil microbial biomass and their distribution across different microbial groups. These environmental factors were the most important drivers affecting bacterial PLFAs. However, no significant relationships were observed between fungal PLFAs and environmental factors. Mycorrhizal colonization differed significantly among the different host species and regions. The RDA results indicated that environmental factors, in particular mean annual precipitation (MAP), pH, available phosphorus (P) and carbon/ nitrogen ratio (C/N) explained 44.8 % of AM fungal root colonization and spore number variation. Mycorrhizal colonization was positively correlated with pH but negatively with P, C/N and MAP. Concerning AM fungal spore number, it was positively linked to P and MAP. In contrast, it was inversely related to soil pH. Highlighting the main edaphic and climatic factors disturbing soil microorganisms, especially AM fungi, helps to better understand how environmental change will influence soil microbial communities in Mediterranean rainfed cereal systems.

EKSPLORASI MIKORIZA ARBUSKULA INDIGENOUS PADA RHIZOSFER VEGETASI LAHAN PASCATAMBANG BATUBARA

Different types of vegetation have the potential to affect a type of spore, the number of spores, and the level of colonization in the roots. This study aims to determine the diversity of genus and the number of arbuscular mycorrhizal spores as well as the level of colonization in the vegetation of Bull Grass (Paspalum conjugatum Berg), Kemunting (Rhodomyrtus tomentosa), and Kirinyuh (Chromolaena odorata L) on post-coal mining land in Margomulyo Village, Kutai Kartanegara, Kalimantan. East. The research was conducted from February to October 2020. Sampling was carried out by purposive sampling based on the land cover area of the Bull grass, Kemunting, and Kirinyuh vegetation with four replications. Laboratory analysis was conducted in Biology Laboratory, Department of Soil Science, Faculty of Agriculture, Brawijaya University and chemical analysis of soil at the Laboratory of Soil, Faculty of Agriculture, University of Muhammadiyah Malang. The results showed that the genus Glomus was found from each of these vegetations with the number of spores in the Bull grass, Kemunting, and Kirinyuh vegetation, respectively 196 spores, 122 spores, and 100 spores per 100 g of soil, and the level of colonization in these vegetations respectively 83.33%, 63.33%, and 51.50%.

KERAGAMAN JENIS DAN POPULASI MIKORIZA ARBUSKULA DALAM BERBAGAI KELOMPOK UMUR PINUS TUMPANGSARI KOPI DI UB FOREST

Differences in tree age and cropping systems may influence the microbial diversity, including fungal species and population. The purpose of this study was to determine the diversity, of species and population of arbuscular mycorrhiza spores and the relationship between the number of arbuscular mycorrhiza spores and the soil chemical properties in different pine age group and coffee as an intercropping system at sloped areas. The study was conducted from April to July 2017. The study used a survey method with 5 age groups (KU) and three replications. The study was divided into 3 stages: 1). collection of soil and root samples, as well as measuring plot characteristics (i.e. basal area, canopy cover, standing litter mass); 2). Measurement of Mycorrhizal in the laboratory (spore extraction, spore identification, root colony percentage analysis); 3). Soil Chemical Analysis (pH, total P, available P). All data was tabulated, and tested using ANOVA with Randomized Block Design. If there is a significantly different, a further LSD test is performed with a level of 5%. Correlation and regression tests were performed to determine the relationship between parameters. The results showed that there were significant differences in the parameters of canopy density, number of genus spores of Acaulospora 100 g-1 soil, Soil pH, and total P in the soil. However, the study was unable to detect significant differences in, other parameters, such as root infection, number population of Glomus and Gigaspore, available P, etc.. The correlation test showed that the increase in the age group of the coffee intercropping system did not correlate with the number of arbuscular mycorrhizae in each plot observed. The number of Arbuscular Mycorrhizal Spores in each age group of intercropping pine did not correlate with the soil's chemical properties (pH, P-Total, P-Available).

Isolation and characterization of Arbuscular Mycorrhizal (AM) fungi from the rhizospheric soil of some medicinal plants

The present investigation was carried out to estimate the colony forming units of indigenous fungi and to study the diversity and Arbuscular mycorrhizal (AM) of some medicinal plants. The study was also aimed to estimate and isolate the Arbuscular mycorrhizal (AM) spore population from the rhizospheric soil of some important medicinal plants from the Botanical garden of College campus. All the selected medicinal plants i.e., Mentha sp. Ocimum sanctum, Bryophyllum sp. Adhatoda vasica, and Andrographis paniculata showed a very good diversity of rhizospheric soil fungi. The highest number of Colony forming unit (c.f.u) was estimated in Mentha sp (162/10-1) followed by Bryophyllum sp. (156/10-1), Andrographis paniculata (91/10-1), Adhatoda vasica (72/10-1) and Ocimum sanctum (68/10-1). Arbuscular mycorrhizal (AM) spore population was also estimated in all the medicinal plants. The higest number of AM spores was estimated in Andrographis paniculata (121/50gm-1) followed by Ocimum sanctum (112/50gm-1), Adhatoda vasica (94/50gm-1), Bryophyllum sp.(89/50gm-1) and Mentha sp (75/ 50gm-1). The rhizospheric soil fungal diversity including mycorrhizal fungi (Glomus sp.) also was found to be beneficial for increasing the photosynthetic activity and uptake of phosphorus in medicinal plants. Thus, the use of AM inoculum can increase the yield of medicinal plants along with their secondary metabolites to utilize on a sustainable basis as a traditional and herbal medicine for the human welfare.

Phosphorus acquisition by three wheat cultivars contrasting in aluminium tolerance growing in an aluminium-rich volcanic soil

Phosphorus (P) deficiency and aluminium (Al) phytotoxicity are major limitations for crop yield in acid soils. To ameliorate such limitations, agricultural management includes application of lime and P fertilisers, and the use of Al-tolerant plant genotypes. The mechanisms of Al tolerance and P efficiency may be closely related through strategies that decrease the toxicity of the Al3+ ion and increase P availability in soils. However, the effects of soils with high Al saturation on P acquisition by wheat have been little studied under field conditions. The aim of this work was to study Al–P interactions on wheat genotypes of contrasting Al tolerance when grown under field conditions in a volcanic soil with high Al saturation (32%) and low pH (5.0). A field-plot experiment was performed with winter wheat genotypes, two Al-tolerant (TCRB14 and TINB14) and one Al-sensitive (STKI14), with application of 0, 44 and 88 kg P ha–1. At the end of tillering and after physiological maturity (90 and 210 days after sowing), plants were harvested and yield and P and Al concentrations in shoots and roots were measured. Soil acid phosphatase, root arbuscular mycorrhizal (AM) colonisation, AM spore number and soil glomalin were determined. Shoot and root production and P uptake were higher in Al-tolerant genotypes than the sensitive genotype. In addition, root AM colonisation and soil acid phosphatase activity were also higher in tolerant genotypes. By contrast, Al concentration in shoots and roots was higher in the sensitive genotype with a concomitant decrease in P concentration. Grain yield of Al-tolerant genotypes was higher than of the Al-sensitive genotype with and without P fertiliser. Overall, the Al-tolerant genotypes were more effective at P acquisition from soil as well as from P fertiliser added, suggesting that plant traits such as Al tolerance, P efficiency, and AM colonisation potential co-operate in overcoming adverse acid soil conditions.

Arbuscular mycorrhizal and dark septate endophyte fungal associations in Asparagus

We studied the arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in five species of pot-grown Asparagus (A. aethiopicus, A. densiflorus, A. setaceus, A. racemosus, and A. umbellatus). Root colonization by AM and DSE fungi and AM spore numbers in the soil were assessed. AM fungal diversity indices like species richness, Shannon-Weiner index, Simpson's index, evenness, and Jaccard's index were determined. Relationships among the fungal and soil variables were also examined. All the species of Asparagus examined were colonized by both AM and DSE fungi, and these associations have been reported for the first time in four species. Root colonization by both the fungi varied significantly among Asparagus species and was related to each other and soil factors. The AM colonization patterns reported in four Asparagus species for the first time were characterized by either intermediate or Arum-Paris type. The AM fungal community was dominated by members belonging to the Glomerales and was significantly influenced by Asparagus species and soil factors. We conclude that Asparagus species could support a diverse AM fungal community even under pot conditions; however, certain AM fungal species are sensitive to changes in soil factors and host species.

Habitational abiotic environmental factors alter Arbuscular mycorrhizal composition, species richness and diversity index in Abroma augusta L. (Malvaceae) rhizosphere

The scarce occurrence along with over-exploitation of Abroma augusta vis-a-vis its usage by practitioners of traditional medicinal system has augmented its importance among researchers and conservation biologists. The present study was an attempt to examine the alterations induced by abiotic environmental (i.e. climatic, biotic and physiographic) factors related to the plant habitat on the Arbuscular Mycorrhizal (AM) fungal partners of the target plant. Rhizospheric soils collected from 24 study sites of eight natural locations under six habitats from the Brahmaputra valley, Assam, India were assessed for AM populations. Through this study, a total of 22 AM fungal species under three genera (i.e. Glomus, Gigaspora and Acaulospora) were isolated. Riverine habitat augments AM spore density (155±1.19) while fallows are characterized by maximum colonization by hyphae (80±0.45) and arbuscules (10±0.18). It is evident that increase in soil temperature and electrical conductivity, exhibited declining effect on the percent root colonization, AM spore numbers per 50 g of soil as well as AM ecological indices. The association between rhizospheric fungal biota including endomycorrhizae and abiotic soil properties can be exclusively advocated for a broader utilization as an ecological indicator for the conservation of target plant species which is discussed in this research paper.

Fly ash mycorrhizoremediation through Paspalum scrobiculatum L., inoculated with Rhizophagus fasciculatus

Fly ash is the residue produced during the combustion of coal, and its disposal is a major environmental concern worldwide. However, fly ash can ameliorate soils by improving their physical, chemical, and biological properties. Hence, we conducted a study to understand the mycorrhizoremediation of different levels of fly ash (2%, 4%, and 6%) by using kodo millet (Paspalum scrobiculatum L.) inoculated with arbuscular mycorrhizal (AM) fungus Rhizophagus fasciculatus under greenhouse conditions. Fly ash amendment at a low level (2%) significantly enhanced AM colonization, spore number, plant growth, nutrient uptake, nutrient-use efficiencies and grain yield of kodo millet. Nevertheless, inoculation of soils amended with 2% fly ash with the AM fungus further enhanced the AM fungal, plant growth, nutrient uptake and yield parameters. Arbuscular mycorrhizal colonization decreased with increasing concentrations of fly ash amendment; however, such decrease was not linear. Our results also revealed a significantly higher plant growth, root/shoot ratios and nutrient contents in kodo millet shoots raised on 2% fly ash amendment and inoculated with the AM fungus at both harvests. Both fly ash amendment and AM fungus inoculation also significantly influenced the number of grains produced as well as the grain weight. Arbuscular mycorrhizal inoculation and fly ash amendment affected K, Ca, Mg, Na use efficiencies. Plant growth and nutrient parameters were strongly related to the extent of AM fungal colonization in the roots. These observations suggest that the inoculation of AM fungi along with low levels of fly ash amendment could be effectively used for the reclamation of low fertile or marginal soils and in turn fly ash could aid in crop production.

Arbuscular Mycorrhizal and Dark Septate Endophyte Fungal Associations in South Indian Aquatic and Wetland Macrophytes

Investigations on the prevalence of arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal symbioses are limited for plants growing in tropical aquatic and wetland habitats compared to those growing on terrestrial moist or dry habitats. Therefore, we assessed the incidence of AM and DSE symbiosis in 8 hydrophytes and 50 wetland plants from four sites in south India. Of the 58 plant species examined, we found AM and DSE fungal symbiosis in 21 and five species, respectively. We reported for the first time AM and DSE fungal symbiosis in seven and five species, respectively. Intermediate-type AM morphology was common, and AM morphology is reported for the first time in 16 plant species. Both AM and DSE fungal colonization varied significantly across plant species and sites. Intact and identifiable AM fungal spores occurred in root zones of nine plant species, but AM fungal species richness was low. Though no clear relationship between AM and DSE fungal colonization was recognized, a significant negative correlation between AM colonization and spore numbers was established. Our study suggests that the occurrence of AM and DSE fungal symbiosis in plants growing in hydrophytic and wetland habitats is not as common as in terrestrial habitats.

Consortium Effect of Arbuscular Mycorrhizal Fungi and Pseudomonas fluorescens with Various Levels of Superphosphate on Growth Improvement of Cotton (G. arboreum L.)

A pot experiment was conducted to see the impact of arbuscular mycorrhizal (AM) fungi, i.e., Funneliformis mosseae and Acaulospora laevis to cotton (Gossypium arboreum L.) with phosphate-solubilizing bacteria Pseudomonas fluorescens in the presence of different doses of superphosphate, i.e., 750 mg/3 kg soil (half of the recommended dose), 1500 mg/3 kg soil (recommended dose), 3000 mg/3 kg soil (double than the recommended dose) with five replicates resulted in effective plant height, shoot and root biomass, root length, leaf area, root colonization, AM spore number, stomatal conductance, chlorophyll content, shoot and root P content, fiber yield, and acidic and alkaline phosphatase activity. All growth parameters like plant height, fresh and dry shoot weight, fresh and dry root weight, root length, leaf area, AM spore number, percent mycorrhizal root colonization, total chlorophyll content, stomatal conductance, acidic and alkaline phosphatase activity, shoot and root phosphorus content, fiber yield were highest in combination F. mosseae + P. fluorescens of lower concentration. Higher dose of superphosphate markedly reduced or decreased all the growth parameters. So, vigorous growth and maximum yield of cotton can be achieved by inoculation of plant with AM fungi (F. mosseae), P. fluorescens along with half of the recommended dose of superphosphate/lower concentration.

Impact of Arbuscular Mycorrhizal Fungi with Trichoderma viride and Pseudomonas fluorescens on Growth Enhancement of Genetically Modified Bt Cotton (Bacillus thuringiensis)

The present investigation was undertaken to find out efficient strains of Arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae and Acaulospora laevis) alone or in combinations with Pseudomonas fluorescens and Trichoderma viride on growth parameters of Bt cotton (Bacillus thuringiensis) var. NCS-108 (SUNNY). All inoculated seedlings showed significant biomass production than control seedlings. Triple inoculation of A. laevis + T. viride + P. fluorescens showed maximum increment in plant height, fresh and dry root weight, root length, total chlorophyll content, shoot phosphorus content, root phosphorus content, both acidic, and alkaline phosphatase activity, whereas fresh and dry shoot weight, leaf area, AM spore number, and stomatal conductance were found maximum in the combination F. mosseae + A. laevis + T. viride. Maximum fiber yield was found in the combination of F. mosseae + A. laevis + T. viride + P. fluorescens. These results indicate that triple inoculation of A. laevis + T. viride + P. fluorescens followed by the combination F. mosseae + A. laevis + T. viride showed significant response for inoculating Bt cotton in order to get significant growth and field with maximum yield.

AM fungi ameliorates growth, yield and nutrient uptake in Cicer arietinum L. Under salt stress

A pot experiment was performed to see the effect of two indigenous arbuscular mycorrhizal (AM) fungi Glomus mosseae and Acaulospora laevis, alone and in combination on growth, biomass and mineral nutrition of Cicer arietinum under different salinity levels imposed by 4, 8, and 12 dS/m EC solution (sodium chloride, calcium chloride and sodium sulphate). All AM inoculated plants showed significant increment in growth, biomass, mineral nutrition and yield over control. The extent of bioinoculants response on plant growth as well as root colonization decreases with the increase in the level of salinity. Among all the growth parameters plant height (26.4 ± 1.14 cm), root length (13.4 ± 1.67 cm), total chlorophyll (2.33 ± 0.02 mg/100 mg f. wt), root colonization (41.6 ± 2.70%) and AM spore number (63.8 ± 1.78 per 10 gm soil) were recorded highest in dual combination (G. mosseae and A. laevis) at 4 dS/m while fresh shoot (6.80 ± 0.67 gm) and dry shoot weight (0.96 ± 0.18 gm) was found maximum in G. mosseae at the same concentration of salinity. Greater Phosphorus (P) acquisition and yield was observed at 4 dS/m with dual combination (G. mosseae and A. laevis) that possibly be responsible to protect plants from salt stress. Although Nitrogen (N), Potassium (K) and Sodium (Na) contents also declined with increasing salinity. Overall results showed that mycorrhizal colonization improves host plant mineral concentration and thereby increases the growth, yield and nutrient uptake of C. arietinum ameliorating the harmful effect at salinity stress.

Screening and selection of efficient host and sugarcane bagasse as substrate for mass multiplication of Funneliformis mosseae

This investigation reports a novel and low-cost method of inoculum production of arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae (sensu Glomus mosseae), using an organic medium. The experiment is a 3 × 3 × 4 factorial design employing three hosts, maize (Zea mays L.), lemon grass (Cymbopogon nardus (L.) Rendle) and palmarosa (Cymbopogan martini (Roxb.) Wats.), three forms of sugarcane bagasse substrate (fresh, dry and compost) and four different concentrations of each substrate (without substrate, 25, 50 and 100 g pot− 1). Mass multiplication of F. mosseae was measured in terms of AM spore number and per cent root colonization. The plant growth was monitored in terms of plant height, above-ground fresh and dry weights and root fresh and dry weights. All three grasses tested varied in their tendency to be colonized by F. mosseae and in spore formation. Maize was found to be the most appropriate host followed by lemon grass and palmarosa. In the case of maize, a positive relationship was observed between spore number and root colonization rate and compost bagasse with highest concentration, 100 g, resulted in the greatest multiplication of F. mosseae. Maize with 100 g compost bagasse, lemon grass with 25 g of dry and 50 g of compost bagasse and palmarosa with 100 g compost and fresh bagasse showed greatest increase in plant growth.

Multifaceted potential of bioinoculants on red bell pepper (F1 hybrid, Indam Mamatha) production

The present investigation was undertaken to determine the comparative efficacy of two arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae and Acaulospora laevis) with Trichoderma viride and Pseudomonas fluorescens on growth and yield of red bell pepper. The results indicate that F. mosseae colonized the plant roots better as compared to A. laevis and promoted maximum increment in AM spore number, root colonization, leaf area, acid phosphatase activity, early fruit formation along with maximum increase in fruit nitrogen, and protein content. Whereas F. mosseae+P. fluorescens promoted maximum increase in plant height, shoot weight, mycorrhizal dependency, chlorophyll a, alkaline phosphatase activity, and fruit phosphorus content. Regarding root length, root weight, leaf photosynthesis, chlorophyll b, number of fruits per plant and their fresh weight, it was found best in F. mosseae+A. laevis+P. fluorescens. Therefore, soil inoculation with suitable bioinoculant should be used at nursery stage for better yield.

Infection intensity, spore density and inoculum potential of arbuscular mycorrhizal fungi decrease during secondary succession in tropical Brazilian ecosystems

Abstract:Little is known about the relationship involving arbuscular mycorrhizal (AM) fungi and functional groups of plants that characterize different phases of tropical succession. We appraised the AM infection intensity of root cortex and spore density in the soil in sites over tropical successional gradients (grassland, secondary forest and mature forest) for several years in Araucaria, Atlantic and Pantanal ecosystems in Brazil. The intensity of AM infection decreased with advancing successional stages in all ecosystems and it was around 60–80% in early stages of succession, 37–56% in secondary forests and 19–29% in mature forests. Similarly, the AM spore number also decreased with advancing succession and was the highest in early stages (73–123 g−1), intermediate in secondary forests (32–54 g−1) and lowest in the mature forests (10–23 g−1). To verify whether such reductions influenced the potential of AM inoculum in soil, seedlings of Heliocarpus popayanensis (Malvaceae) were grown as test plants in soils obtained from five grasslands, five young secondary forests, and five mature forests in the Atlantic ecosystem. The soil inocula from the grasslands and secondary forests were 7.6 and 5.7 times more effective in stimulating seedling growth than inocula from the mature forests, respectively. Our results show that plant species in grasslands and young secondary forests stimulate the multiplication of AM fungi, leading to a higher potential of the AM inoculum. In later-successional stages, plant investment in AM fungi decreases and the potential of the AM inoculum is also reduced.

Synergy between Glomus fasciculatum and a beneficial Pseudomonas in reducing root diseases and improving yield and forskolin content in Coleus forskohlii Briq. under organic field conditions

Root rot and wilt, caused by a complex involving Fusarium chlamydosporum (Frag. and Cif.) and Ralstonia solanacearum (Smith), are serious diseases affecting the cultivation of Coleus forskohlii, a crop with economic potential as a source of the medicinal compound forskolin. The present 2-year field experiments were conducted with two bioinoculants (a native Pseudomonas monteilii strain and the exotic arbuscular mycorrhizal (AM) fungus Glomus fasciculatum) alone and in combination under organic field conditions in order to evaluate their potential in controlling root rot and wilt. Combined inoculation of P. monteilii with G. fasciculatum significantly increased plant height, plant spread, and number of branches; reduced disease incidence; and increased tuber dry mass of C. forskohlii, compared to vermicompost controls not receiving any bioinoculants. Increase in tuber yields was accompanied by an increase in plant N, P, and K uptake. Co-inoculation of P. monteilii with G. fasciculatum significantly improved the percent AM root colonization and spore numbers retrieved from soil. This suggests P. monteilii to be a mycorrhiza helper bacterium which could be useful in organic agriculture. The forskolin content of tubers was significantly increased by the inoculation treatments of P. monteilii, G. fasciculatum, and P. monteilii + G. fasciculatum.

Reintroduction of a native Glomus to a tropical Ultisol promoted grain yield in maize after fallow and restored the density of arbuscular mycorrhizal fungal spores

AbstractMaize (Zea mays L.) is an important crop in central Thailand where fallow is widely practiced and farmers are interested in crop rotation and beneficial soil biota. A pot experiment using a Typic Paleustult (topsoil + subsoil) from the National Corn and Sorghum Research Centre, Nakhonratchasima Province, Thailand was undertaken over three successive crops to evaluate effects of agronomic practices on populations of arbuscular mycorrhizal (AM) fungi and to determine whether reintroduction of a local Glomus was beneficial to maintain maize yield. The three crops and their treatments were: (1) preceding crop: maize grown in all pots; (2) subexperiment 1: agronomic practices [maize, fallow ± soil disturbance, fallow with solarization, non–AM host (cabbage)]; and (3) subexperiment 2: maize ± Glomus sp. 3 at three rates of P fertilization (0, 33, 92 kg P ha–1). The AM‐fungal community was established under the preceding crop. In subexperiment 1, the three fallow treatments decreased (30%–40%) the total AM spore number in the topsoil whereas there was no change under maize or cabbage. Glomus, the dominant genus, showed sensitivity to fallow. In subexperiment 2, inoculation with Glomus sp. 3 enhanced total AM spore number and root colonization when applied following the three fallow treatments. Furthermore, inoculation promoted grain yield; at nil P following fallow ± soil disturbance, at 33 kg P ha–1 following fallow without soil disturbance, and following solarization. Two treatments, maize following maize and maize following cabbage, did not respond to inoculation with Glomus sp. 3. Overall, the results suggest that reintroduction of Glomus sp. 3, a local AM fungus in this soil, may overcome negative effects of fallow and promote effectiveness of P fertilizer. Further work is needed to evaluate the benefits of other indigenous AM species that persist under modern fertilization practices.

Response of Strawberry plant (Fragaria ananassa Duch.) to inoculation with arbuscular mycorrhizal fungi and Trichoderma viride

The present paper represents the positive role of Arbuscular Mycorrhizal (AM) fungi as biofertilizers in strawberry. Experiments were carried out to assess the effectiveness of Trichoderma viride and AM fungi (Glomus mosseae and Acaulospora laevis) alone or in combination, on the growth and biomass production of strawberry. After 120 days, dual inoculation of A. laevis + T. viride showed maximum increase in plant height (30.5±0.3), fresh shoot weight (10.16±0.20), dry shoot weight (2.82±0.02), fresh root weight (6.70±0.10), total chlorophyll (0.841±0.05) and phosphorus content in root (1.13±0.02) as compared to control. However root colonization and AM spore number were maximum in G. mosseae + A. lavies (90.76±1.32) and in G. mosseae (211.16±2.56) respectively as compared to uninoculated plants. Triple inoculation of G. mosseae + A. laevis + T. viride (12.33± 057) was effective in increasing the leaf area.