Growth Of Mycorrhizal Plants Research Articles

The performance of mycorrhizae, rhizobacteria, and earthworms to improve Bermuda grass (Cynodon dactylon) growth and Pb uptake in a Pb-contaminated soil.

The current study was conducted to determine the combined performance of soil micro- and macro-organisms to stimulate the growth and lead (Pb) uptake of Bermuda grass (Cynodon dactylon (L.) Persi.) in a soil polluted with Pb-mining activities. Plants were inoculated with a mixture of arbuscular mycorrhizal (AM) fungal species, plant growth-promoting rhizobacteria (PGPR) species, and epigeic earthworms (Eisenia fetida) either alone or in combination. Results demonstrated antagonistic interactions between AM fungi and PGPR or between AM fungi and earthworms on the growth of mycorrhizal plants by increasing the availability of both phosphorus (P) and Pb in the soil solution and the subsequent reduction of mycorrhizal root colonization following inoculation of PGPR or earthworms. Plant biomass was negatively correlated with soil-available Pb, but positively with the percentage of root colonization by AM fungi. Additionally, mycorrhizal root colonization was negatively correlated with soil-available P and Pb concentrations. The triple inoculation of AM fungi with PGPR and epigeic earthworms as a bioaugmentation tool could result in a synergistic interaction effect on plant Pb bioaccumulation and uptake, enhancing the efficiency of phytoremediation and eco-restoration of Pb-polluted sites. In conclusion, the use of Bermuda grass in association with functionally dissimilar soil organisms demonstrated a high effectiveness for Pb in situ phytoremediation, specifically Pb phytostabilization, to reduce Pb mobilization in the environment.

Arbuscular mycorrhizal inoculation in Citrus volkameriana Tan & Pasq

Objective. We evaluated the effect of arbuscular mycorrhizal inoculation in Citrusvolkameriana Tan & Pasq plants with the application of Glomus spp Zac- 19 (G.claroides, G. diaphanum and G. albidum) to assess growth under greenhouseconditions without fertilizer application.Methodology. The evaluated treatments were inoculation with 2,4,6,8, and 10 g ofinoculum, plus a control without inoculation in an experimental design of completerandomized blocks with three replications. Variables were plant height, stem diameter,number of leaves, foliar area, dry weight, and mycorrhizal colonization.Results. A statistically significant response (p?0.01) to inoculation wasobserved, registering higher growth of mycorrhizal plants. The inoculation wasconsidered appropriate for all the levels evaluated. The outstanding treatment was 10 gof inoculum that produced plants with 110.16 cm in height for the last sampling; 38.56leaves per plant; 1.13 cm stem diameter; 35.95 g dry weight of root; 76.88 g dry weightof the aerial part of the plant; 225.03 cm 2 of leaf area per plant and 88.87% ofmycorrhizal colonization.Conclusions. The application of 10 g per plant to the roots of Citrus volkameriana fromthe Glomus Zac-19 arbuscular mycorrhizal consortium promoted the production of morevigorous plants for grafting, without the application of chemical fertilizer.

Effect of Glomus fasciculatum On Nutrient Uptake and Growth of a Medicinal Plant, Coleus forskohlii

Aims: Coleus forskohlii Briq. (syn. Coleus barbatus Benth.) belonging to the family Lamiaceae is a well known plant throughout the country and known as ‘pashanbhedi’ in Sanskrit and ‘pathatchur’ in Hindi is one of the most potential medicinal plants of the future, as its pharmacoproperties have been discovered only recently. Its tuberous roots are found to be rich source of forskolin which is being used as a remedy for hypertension, glaucoma, asthma, congestive heart failures and certain types of cancers and also being use as vegetables. In addition, forskolin is reported to have used in the preparation of medicines for controlling body weight, preventing hair greying and restoring normal colour of grey hairs. Its foliage is also employed in treating intestinal disorders and used as a condiment since a long time. Keeping the above views in mind, the present investigation was undertaken to study the influence of an arbuscular mycorrhizal (AM) fungus, G. fasciculatum on phosphorus uptake and growth of Coleus forskohlii.
 Study Design: Various tests or experiments were done in this study. Total leaf tissue phosphorus content was determined following the Microkjeldhal method of Jackson (1973) and chlorophyll estimation was done following the method of Mahadevan and Sridhar (1982) .Root colonization of C. forskohlii by G. fasciculatum was observed by the ‘Rapid clearing and staining technique’ (Phillips & Hayman, 1970). Forskolin content in C. forskohlii tubers was estimated by High performance liquid chromatography (HPLC).
 Place and Duration of Study: Sample: The experiment was carried out in the Department of Botany, Burdwan University. A soil culture of Glomus fasciculatum was propagated as endomycorrhizal species in Zea mays as suitable host in pot culture using sterile sand and soil (pH 5.6; organic carbon 0.6%, P content 45 ppm) in 1:1 ratio. 400 gm of rhizosphere soil with AM-inoculated root fragments of Zea mays was introduced in the dry, loamy, fine-textured soil (pH 5.8; organic carbon 0.6%, P content 45 ppm, total nitrogen 0.03%) of pot culture (2.0 kg of soil per pot) at a depth of 2 inches below the Coleus cutting (12-16 cm long comprising 3-4 pairs of leaves) being planted, between June 2011 and July 2012.
 Results: Responses of an arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum on phosphorus uptake by the plant at different developmental phases have been studied. The result indicates that symbiotic association of mycorrhizal fungus amounts to greater uptake of phosphorus and increased chlorophyll content in AM treated plants than in non mycorrhizal plants which gradually happened to be maintained throughout their developmental stages. Different growth parameters like plant height, root length, no. of roots, no. of leaves, no. of branches, fresh weight of shoot, roots, tubers and forskolin content were significantly higher in AM treated plants than in respective controls.
 Conclusion: The better growth of mycorrhizal plants was attributed to improved nutrient uptake, especially phosphorus. The result suggested that G. fasciculatum is one of the most potentially effective bio-fertilizer of Coleus forskohlii.

Foliar Application of Chitosan Increases Tomato Growth and Influences Mycorrhization and Expression of Endochitinase-Encoding Genes.

Nowadays, applying bio-organic fertilizer (e.g., chitosan, Ch) or integrating beneficial microorganisms (e.g., arbuscular mycorrhizal fungi, AMF) are among the successful strategies to promote plant growth. Here, the effect of two application modes of Ch (foliar spray or root treatment) and Ch-derived nanoparticles (NPs) on tomato plants colonized with the AMF Rhizophagus irregularis were analyzed, thereby focusing on plant biomass, flowering and mycorrhization. An increase of shoot biomass and flower number was observed in arbuscular mycorrhizal (AM) plants sprayed with Ch. The interaction with AMF, however, was reduced as shown by decreased mycorrhization rates and AM-specific gene expression. To get insights into Ch effect on mycorrhization, levels of sugars, jasmonates, abscisic acid, and the expression of two chitinase-encoding genes were determined in mycorrhizal roots. Ch had no effect on sugar and phytohormone levels, but the reduced mycorrhization was correlated with down- and upregulated expression of Chi3 and Chi9, respectively. In contrast, application of NPs to leaves and Ch applied to the soil did not show any effect, neither on mycorrhization rate nor on growth of mycorrhizal plants. Concluding, Ch application to leaves enhanced plant growth and flowering and reduced interaction with AMF, whereas root treatment did not affect these parameters.

Differential growth response of Curculigo orchioides to native arbuscular mycorrhizal fungal (AMF) communities varying in number and fungal components

The study reports diversity of arbuscular mycorrhizal fungal (AMF) species in the rhizosphere of an endangered anticancerous herb – Curculigo orchioides Gaertn. in its natural habitat. A total of 18 species of AMF, belonging to three genera ( Acaulospora, Glomus and Gigaspora) were recorded, with Glomus microcarpum being the most abundant species type. The AMF species composition across the study sites appeared to be influenced by soil pH rather than soil P and vegetation. Acaulospora laevis spores were restricted to sites where the soil pH was acidic. The effectiveness of these native AMF species on growth performance of C. orchioides plants was compared under experimental conditions. In general, the mycorrhizal plants were superior in most of the evaluated parameters, but the extent to which the growth of mycorrhizal plants was influenced varied with the inocula used. The plants inoculated with mixed consortia containing maximum AMF species richness exhibited improved growth in comparison to consortia containing lower AMF diversity and monospecies cultures. The variable plant responses observed with any two consortia having same species richness in the present study could be due to variable component AMF species and their relative abundance. These results emphasize the need to protect the below-ground diversity of AMF and recommend their usage for restoration practices.

Effects of Bifenthrin on Mycorrhizal Colonization and Growth of Corn

The insecticide bifenthrin is a synthetic pyrethroid required by regulation for the production of nursery crops to suppress the red imported fire ant (Solenopsis invicta) in Orange and Riverside counties in California. We conducted a greenhouse experiment to analyze the effects of different rates of bifenthrin on the growth and mycorrhizal colonization of ‘Silver Queen’ corn (Zea mays) inoculated with VAM 80®, a mycorrhizal inoculum with spores, hyphae, and root pieces colonized by Glomus spp., used to inoculate California native plants in containers. Corn was used because it is the standard indicator plant used for mycorrhizal inoculum potential assays and it is a good host for arbuscular mycorrhizal fungi propagation. The application of bifenthrin had no detrimental effects on mycorrhizal colonization of corn. There were no significant differences in the root length colonized by arbuscules, vesicles, or in the total percentage of mycorrhizal colonization obtained in the plants grown with the different bifenthrin rates 6 weeks after transplanting. However, there were significant interactions on the effects of bifenthrin and mycorrhizal colonization on plant growth. The addition of 12, 15, and 25 ppm of bifenthrin reduced corn biomass of nonmycorrhizal plants, but had no effect on the growth of mycorrhizal plants. There were no significant differences between the mycorrhizal and nonmycorrhizal plants grown with 0, 10, and 12 ppm of bifenthrin. In contrast, inoculation with VAM 80® increased the shoot dry weight of plants grown with 15 and 25 ppm of bifenthrin. This study showed that mycorrhizal colonization can be helpful to overcome some of the negative effects of bifenthrin on the growth of corn.

Effects of Bifenthrin on Mycorrhizal Colonization and Growth of Corn

The insecticide bifenthrin is a synthetic pyrethroid required by regulation for the production of nursery crops to suppress the red imported fire ant (Solenopsis invicta) in Orange and Riverside counties in California. We conducted a greenhouse experiment to analyze the effects of different rates of bifenthrin on the growth and mycorrhizal colonization of ‘Silver Queen’ corn (Zea mays) inoculated with VAM 80®, a mycorrhizal inoculum with spores, hyphae, and root pieces colonized by Glomus spp., used to inoculate California native plants in containers. Corn was used because it is the standard indicator plant used for mycorrhizal inoculum potential assays and it is a good host for arbuscular mycorrhizal fungi propagation. The application of bifenthrin had no detrimental effects on mycorrhizal colonization of corn. There were no significant differences in the root length colonized by arbuscules, vesicles, or in the total percentage of mycorrhizal colonization obtained in the plants grown with the different bifenthrin rates 6 weeks after transplanting. However, there were significant interactions on the effects of bifenthrin and mycorrhizal colonization on plant growth. The addition of 12, 15, and 25 ppm of bifenthrin reduced corn biomass of nonmycorrhizal plants, but had no effect on the growth of mycorrhizal plants. There were no significant differences between the mycorrhizal and nonmycorrhizal plants grown with 0, 10, and 12 ppm of bifenthrin. In contrast, inoculation with VAM 80® increased the shoot dry weight of plants grown with 15 and 25 ppm of bifenthrin. This study showed that mycorrhizal colonization can be helpful to overcome some of the negative effects of bifenthrin on the growth of corn.

Uptake and metabolism of nitrate in mycorrhizal plants as affected by water availability and N concentration in soil

SummaryWe compare the effect of arbuscular mycorrhizal (AM) colonization and PO4−3 fertilization on nitrate assimilation, plant growth and proline content in lettuce plants growing under well‐watered (−0.04 MPa) or drought (−0.17 MPa) conditions. We also tested how AM‐colonization and PO4−3 fertilization influenced N uptake (15N) and the percentage of N derived from the fertilizer (% NdfF) by plants under a concentration gradient of N in soil. Growth of mycorrhizal plants was comparable with that of P‐fertilized plants only under well‐watered conditions. Shoot nitrogen content, proline and nitrate reductase activity were greater in AM than in P‐fertilized plants under drought. The addition of 100 μg g−1 P to the soil did not replace the AM effect under drought. Under well‐watered conditions, AM plants showed similar (at 3 mmol N), greater (at 6 mmol N) or lesser (at 9 mmol N) %NdfF than P‐fertilized plants. Comparing a control (without AM inoculation) to AM plants, differences in % NdfF ranged from 138% (3 mmol N) to 22.6% (6 mmol N) whereas no differences were found at 9 mmol N. In comparison with P fertilization, mycorrhizal effects on %NdfF were only evident at the lowest N levels, which indicated a regulatory mechanism for N uptake in AM plants affected by N availability in the soil. At the highest N level, P‐fertilized plants showed the greatest %NdfF. In conclusion, AM symbiosis is important for N acquisition and N fertilizer utilization but this beneficial mycorrhizal effect on N nutrition is reduced under large quantities of N fertilizer.

Improvement of Micronutrient Uptake of Valuable Broadleaves in Interaction With Glomus mosseae

Excessive exploitation by humans has in the last century depleted valuable broadleaf trees in Italian forests, and reforestation is desirable. The present work evaluated the impact of a vescicular-arbuscular mycorrhizal (VAM) fungus on growth and on micronutrient accumulation by the plant-hosts. Four species of trees, Prunus avium L., Fraxinus excelsior L., Acer pseudoplatanus L., and Juglans nigra L. were inoculated with Glomus mosseae Nicol. & Gerd., a VAM fungus (Zygomycetes, Glomales) , and grown in a greenhouse. VAM infection and root colonization, tree growth, and micronutrient accumulation were evaluated after 2 years of growth. An enhanced growth of mycorrhizal plants was characterized by a general improvement, varying from species to species, of the micronutrient concentration in stems and roots. Therefore, VAM infection of the plants studied could have improved transplanting stress and the slow growth typical of these species. Several researchers have reported beneficial effects on trees from ectomycorrhizal fungi, but literature on VAM symbiosis of tree species is limited. This work contributes to our understanding of the effects of VAM symbiosis on the accumulation of certain micronutrients in valuable woody tree species.

Response of Sauropus androgynus to soil phosphorus concentration and mycorrhizal colonization

Abstract Thirty three‐day‐old seedlings of nonmycorrhizal Sauropus androgynus were transplanted into pots containing a subsurface Oxisol uninoculated or inoculated with Glomus aggregation at three target soil solution phosphorus (P) concentrations. While no evidence of vesicular‐arbuscular mycorrhizal fungal (VAMF) colonization was noticed in the uninoculated soil, sauropus roots were colonized to the extent of 54%, 60% and 38% in the inoculated soil if target soil P concentrations were 0.014, 0.02 and 0.2 mg/L. VAMF colonization led to significant increases in tissue P and shoot dry matter accumulation at the first two soil P concentrations but not at the highest concentration. Root dry matter yield of mycorrhizal sauropus was greater than that of nonmycorrhizal sauropus at all soil P concentrations tested. Although mycorrhizal inoculation effects at soil P concentrations of 0.014 and 0.02 mg/L were comparable, growth of mycorrhizal plants was greater at the latter P concentration than at the former. Gro...

Effects of nitrogen source on growth, nutrition, photosynthetic rate and nitrogen metabolism of mycorrhizal and phosphorus‐fertilized plants of Lactuca sativa L.

summaryPlants of Lactuca sativa L. cv. Romana were inoculated with two vesicular‐arbuscular (VA) mycorrhizal fungi, Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe and Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. & Trappe, or provided with phosphorus. These three treatments plus a control were supplemented with 3.0 mM nitrogen as nitrate or ammonium in 1 of 5 NO3−/NH4+ ratios. Leaf and root weights, N, P, K, Ca and Mg absorption, as well as the percentage of root length colonized, were evaluated. Physiological parameters such as leaf area, photosynthetic rate, glutamine synthetase (EC 6.3.1.2) and nitrate reductase (EC 1.6.6.1) activity and leaf proline accumulation were also determined. Mycorrhizal lettuce and P‐fertilized plants derived significantly more benefit from N fertilization regardless of the N‐source than did controls. Ammonium was a better N‐source for non‐mycorrhizal plants and nitrate for mycorrhizal plants. P‐fertilized lettuce reached maximum growth when N was supplied as 50% NO3−/ 50% NH4+ so that mycorrhizal status particularly affected the plant response to the form of N provided. Growth of mycorrhizal plants was comparable to non‐mycorrhizal P‐fertilized plants when N was provided as 100% NH4+ or 25 % NO3−/75 % NH4+. When N applications were as 50% NO3−7 50% NH4+ or 75% NO3−/25% NH4+, growth of P‐fertilized plants was greater than mycorrhizal ones. Lettuce colonized by G. mosseae grew fastest when fed nitrate only. Separation of NO3− and NH4+assimilation into shoot and root compartments may account for the differential effects of such ions into symbiotic and non‐symbiotic plants. Uptake or metabolism of nitrogenous forms was particularly affected in G. mosseae‐colonized plants, independent of P nutrition. P fertilization increased activities of nitrate reductase (NR) by 29 % and glutamine synthetase (GS) by 24% compared with activities in control plants. In the case of G. fasciculatum‐colonized plants, NR and GS were increased 54% and 117 %, respectively, over control activities. In general, concentration of minerals, except Ca, were increased in mycorrhizal and P‐fertilized plants compared with controls. Assimilation of CO2 and accumulation of proline were increased in G. fasciculatum‐colonized lettuce under all N regimes.

EFFICACY OF ENDOMYCORRHIZAL‐FUNGUS ISOLATES AND INOCULUM QUANTITIES REQUIRED FOR GROWTH RESPONSE*

SummaryIsolates of Glomus macroncarpum Tul. & Tul. grown in soil cultures from single spores were tested at known numbers of propagules ml−1 soil for their efficacy in promoting growth of bell pepper (Capsicum annuum L.) seedlings. The soil cultures, propagated under similar growth conditions, had from 0.02 to 25 propagules ml−1 as measured by the most probable number technique. Seven cultures with similar levels of inoculum density (a median of 7 propagules ml−1) were used undiluted, and at 10−1 and at 10−2 dilutions to test efficacy of the isolates. Also, cultures with originally dissimilar propagule levels (0.02 to 15 ml−1) were diluted to uniform inoculum density levels and tested for efficacy.Large intra‐species variation in efficacy occurred in isolates collected from different soils and in those isolated from the same soil. Differences in the growth enhancement ability of isolates were evident from four weeks after seeding until harvest. The best isolates were superior at all inoculum levels tested but the ranking of isolates differed with the inoculum density.A significant positive correlation was found between initial G. macrocarpum propagules ml−1 soil and all plant height and weight parameters measured. Growth of mycorrhizal plants was significantly greater than that of non‐mycorrhizal plants when more than 0.5 propagule ml−1 was present. With more than 5 ml−1, 70% of the isolates were effective. A minimum level of 1 propagule ml−1 is suggested for infestation of pepper seed beds; greater benefits can be expected from higher levels up to at least 10 to 15 propagules ml−1.

Vesicular arbuscular mycorrhizal mediation of grass response to acidic and heavy metal depositions

The perennial bunchgrassEhrharta calycina was grown with and without V.A.M. fungal infection (Glomus fasciculatum) in a sandy loam exposed to a range of acidic and heavy metal depositions. Heavy metals (Cu, Ni, Pb, Zn, Fe, and Co) were applied in simulated rain (pH 3.0, 4.0, and 5.6) at deposition rates approximating those observed to result from smelter efluents. Metal concentrations in the roots and shoots of mycorrhizal plants were greater than those of non-mycorrhizal plants. Mycorrhizal enhancement of plant metal uptake increased with greater acidity and higher heavy metal content of treatment. The growth of mycorrhizal plants was reduced compared to non-mycorrhizal plants when metal depostion was combined with simulated acid rain. We propose that mycorrhizal enhancement of heavy metal uptake caused reduced growth in plants exposed to acidic and heavy metal depositions.