Effect Of Vesicular-arbuscular Mycorrhizal Fungi Research Articles

Causal Agents of Root Rot and the Effect of Vesicular-Arbuscular Mycorrhizal Fungi in Seedlings of Rhodiola rosea in Alberta, Canada

Causal Agents of Root Rot and the Effect of Vesicular-Arbuscular Mycorrhizal Fungi in Seedlings of Rhodiola rosea in Alberta, Canada

Alberta and Saskatchewan Joint Regional Meeting, 2008

Alberta and Saskatchewan Joint Regional Meeting, 2008

Nature Farming with Vesicular-Arbuscular Mycorrhizae in Bangladesh

Summary Systematic research on the effect of vesicular-arbuscular mycorrhizal fungi with different agricultural crops, sand dune plants and plantation crops has been carried out in Bangladesh for last few years. Large numbers of VA-mycorrhizal fungi have been detected in different soil types for identification and inoculum production and for use in nurseries and the field as an alternative to chemical fertilizers and pesticides and to progress towards nature farming. The VAM fungi not only absorb and translocate immobile nutrients like phosphorus, zinc and copper (especially phosphorus) through external hyphae, but also play important roles in inter- and intra-specific transfer of carbon, phosphorus, and nitrogen from plant to plant. VAM fungi may also protect plants from certain root-infecting pathogens, improve plant-water relations, enhance the establishment and growth of micro-propagated plants, and increase plant tolerance to salinity. VAM fungi can improve the ecological and environmental conditions of the country and its agriculture by reducing the farmer's dependence and expenditure on chemical fertilizers and pesticides. Effective mycorrhizal inoculum can be introduced directly to the field or indirectly through the production of VAM-infected seedlings from nurseries. The gap of knowledge on the occurrence of VAM fungi in association with different agricultural and forest crops is still immense in Bangladesh. This article has been prepared to draw attention of agricultural scientists, plant physiologist, forest managers, policy-makers and different government and non-government officials towards nature farming systems utilizing VAM and possibility of utilizing VAM in production system.

Mycorrhizae, biocides, and biocontrol. 1. Herbicide-mycorrhiza interactions in soybean and cocklebur treated with bentazon

Interactions between herbicides and vesicular-arbuscular mycorrhizal (VAM) fungi are little-known but may differentially affect the development of tolerant and susceptible plants. We conducted this greenhouse study to determine if VAM fungi modify the effects of the herbicide bentazon (3-isopropyl-1H-2,1,3-benzothidiazin-(4)3H-one 2,2-dioxide) on soybean ( Glycine max (L.) Men.) and common cocklebur ( Xanthium strumarium L.). The experiment was designed as an eight-treatment, 2 × 2 × 2 factorial. Individual potted soybean or cocklebur plants were grown in a high (28 mg kg −1) P-content soil. The plants were colonized by VAM fungi (a mixture of Glomus etunicatum Becker and Gerdemann, Glomus leptotichum Schenck and Smith, and Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe) and sprayed with bentazon. Alternatively, they were exposed only to VAM fungi or to the herbicide, or to neither of these factors. The effects of VAM fungi on plant dry mass were small, but larger in cocklebur than in soybean, especially for the herbicide-treated plants. Root/shoot ratios in cocklebur were larger and shoot dry matter content smaller than those in soybean. The VAM effect in the herbicide-treated plants was greater than in the nontreated ones for both parameters. Colonized root length in cocklebur was drastically reduced by the herbicide (43%), as were leaf dry weight and N, P, and K concentrations. Changes were small, and generally not significant in soybean. Gradual necrosis of treated cocklebur shoots was related to an accelerated loss of shoot dry matter, especially in VAM plants. The data suggest that changes in source-sink relations following herbicide treatment favor enhanced export of shoot dry matter to the roots in susceptible relative to tolerant plants. This biomass may be preferentially available for export from susceptible-plant roots to the soil system through the VAM mycelium.

Iron acquisition by mycorrhizal maize grown on alkaline soil

Abstract Vesicular‐arbuscular mycorrhizal fungi (VAMF) are known to improve the mineral nutritional status of plants. Since information on effects of VAMF on plant iron (Fe) nutrition is limited, an Fe deficient‐susceptible maize (Zea mays L., ysi/ysi) was grown on alkaline Quinlan (Typic Ustochrept, pH 8.0) and Ulysses (Aridic Haplustoll, pH 7.8) soils with Glomus VAMF isolates G. etunicatum WV579A (Ge), G. diaphanum WV579B (Gd), and G. intraradices WV894 (Gi) to determine plant growth responses to VAMF associations and efficacy of these VAMF isolates to enhance Fe acquisition. Shoot and root dry matter (DM) were higher in mycorrhizal (+VAM) then in nonmycorrhizal (‐VAM) plants, and followed a sequence of Ge > Gd ≥ Gi > ‐VAM. Root DM of Ge plants was higher than other +VAM plants. Even though relatively low, leaf chlorophyll (SFAD unit) readings were higher in +VAM than in ‐VAM plants and followed a sequence similar to DM. Plants colonized with Gi had higher leaf Fe, phosphorus (P), and zinc (Zn) concent...

Effects of Vesicular-Arbuscular Mycorrhizal Fungi on Satsuma Mandarin Tree Growth and Water Stress Tolerance and on Fruit Development and Quality.

The effects of vesicular-arbuscular mycorrhizal (VAM) fungi were studied at low concentrations of applied phosphorus (P) on satsuma mandarin (Citrus unshiu Marc. cv. Okitsu wase) trees which were grafted on trifoliate orange (Poncirus trifoliata Raf.) rootstock. The VAM fungi used were Glomus ambisporum Smith and Schenck, Glomus fasciculatum (Thaxter) Gerdemann and Trappe emend. Walker and Koske, Glomus mosseae (Nicolson and Gerdemann) German and Trappe, and Gigaspora ramisporophora Spain.The trees that were inoculated with the VAM fungi grew larger and had better fruit quality as compared with non VAM control trees. The fruit of former were larger, had higher sugar contents in the juice, and better peel color in both 1992 and 1993 than did the latter. In the non VAM control trees, there was a significant difference between seasons in fruit size and quality. This difference is attributed to the low rainfall in 1992 resulting in high sugar content while fruit development was retarded. In 1993, however, heavy precipitation from June to November produced large fruit, but with lower sugar content.After water shortage treatment of 10 days, the water stress tolerance of satsuma mandarin trees was improved by the inoculation of a VAM fungus (Gigaspora ramisporophara).

Effect of vesicular-arbuscular mycorrhizal fungi on verticillium wilt of cotton

The development of vesicular-arbuscular mycorrhizal fungi (VAMF): Glomus mosseae (Nicol and Gerd.) Gerdemann and Trappe, Glomus versiforme (Karsten) Berch, Sclerocystis sinuosa Gerdemann and Bakhi and Verticillium dahliae and the effects of the VAMF on the verticillium wilt of cotton (Gossypium hirsutum L. and Gossypium barbadense L.) were studied with paper pots, black plastic tubes and clay pots under natural growth conditions. All of the tested VAMF were able to infect all the cotton varieties used in the present experiment and typical vesicles and arbuscules were formed in the cortical cells of the cotton roots after inoculation. The cap cells, meristem, differentiating and elongating zones of the root tip were found to be colonized by the VAMF. In the case of most V. dahliae infection, the colonization occurred mostly from the root tip up to 2 cm. VAMF and V. dahliae mutually reduced their percentage of infection when inoculated simultaneously. VAMF inoculation reduced the numbers of germinable microsclerotia in the soil of the mycorrhizosphere, while the quantity of VAM fungal spores in the soil was not influenced by infection of with V. dahliae. The % of arbuscule colonization in roots was negatively correlated with the disease grades, while the numbers of vesicles in roots were not. These results suggest that certain vital competition and antagonistic reactions exist between VAMF and V. dahliae. VAMF reduced the incidence and disease indices of verticillium wilt of cotton during the whole growth phase. It is evident that cotton seedling growth was promoted, flowering was advanced, the numbers of flowers and bolls were increased, and this resulted in an increase in the yield of seed cotton. Among the VAMF species, Glomus versiforme was the most effective, and Sclerocystis sinuosa was inferior. So far as the author is aware, such an effect of VAMF on the increase of cotton wilt tolerance/resistance is reported here far the first time.

Effect of Vesicular-Arbuscular Mycorrhizal Fungi on the Growth, Photosynthesis, Transpiration and the Distribution of Photosynthates of Bearing Satsuma Mandarin Trees.

The response of satsuma mandarin (Citrus unshiu Marc. cv. Okitsu wase) on trifoliate orange (Poncirus trifoliata Raf.) rootstocks to inoculation of vesicular-arbuscular mycorrhizal (VAM) fungi, such as Glomus ambisporum Smith and Schenck, Gloumus fasciculatum (Thaxter) Gerdemann and Trappe emend. Walker and Koske, Glontus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, and Gigaspora ramisporophara Spain was studied at low phosphorus (P) application.Under high air temperature stress conditions in August, the photosynthetic (Pn) and transpiration (Tr) rates of VAM-inoculated trees were faster than non VAM ones. But in September when air temperature decreased, the Pn and Tr rates did not differ significantly between VAM-inoculated trees and non infected ones. In general, infected trees had larger leaf area and higher leaf P concentration and the tree growth was more vigorous than was that of non infected ones.When 13CO2 was fed to fruit-bearing trees under the optimal air temperature conditions, fruits were the strongest sink for photosynthates and new leaves were the second strongest. The leaves of VAM and non VAM trees assimilated 13CO2 equally fast per unit leaf area, and the distribution of 13C into various parts of the bearing trees did not differ. VAM trees, however, had 3 times more photoassimilates per tree than uninfected ones because the former had a leaf area 3 times larger than the latter and grew more vigorously.

Synergistic effects of vesicular-arbuscular mycorrhizal fungi and diazotrophic bacteria on nutrition and growth of sweet potato (Ipomoea batatas)

Sweet potatoes were micropropagated and then transplanted from axnic conditions to fumigated soil in pots in the greenhouse. Spores of Glomus clarum were obtained from Brachiaria decumbens or from sweet potatoes grown in soil infected with this fungus and with an enrichment culture of Acetobacter diazotrophicus. Three experiments were carried out to measure the beneficial effects of vesicular-arbuscular mycorrhizal (VAM) fungi-diazotroph interactions on growth, nutrition, and infection of sweet potato by A. diazotrophicus and other diazotrophs obtained from sweet potato roots. In two of these experiments the soils had been mixed with 15N-containing organic matter. The greatest effects of mycorrhizal inoculation were observed with co-inoculation of A. diazotrophicus and/or mixed cultures of diazotrophs containing A. diazotrophicus and Klebsiella sp. The tuber production was dependent on mycorrhization, and total N and P accumulation were increased when diazotrophs and G. clarum were applied together with VAM fungal spores. A. diazotrophicus infected aerial plant parts only when inoculated together with VAM fungi or when present within G. clarum spores. More pronounced effects on root colonization and intraradical sporulation of G. clarum were observed when A. diazotrophicus was co-inoculated. In non-fumigated soil, dual inoculation effects, however, were of lower magnitude. 15N analysis of the aerial parts and roots and tubers at the early growth stage (70 days) showed no statistical differences between treatments except for the VAM+Klebsiella sp. treatment. This indicates that the effects of A. diazotrophicus and other diazotrophs on sweet potato growth were caused by enhanced mycorrhization and, consequently, a more efficient assimilation of nutrients from the soil than by N2 fixation. The possible interactions between these effects are discussed.

Effects of species of VA-mycorrhizal fungi on growth and mineral uptake of sorghum at different temperatures

Sorghum [Sorghum bicolor (L.) Moench] plants were grown in growth chambers at 20, 25 and 30°C in a low P Typic Argiudoll (3.65 µg P g−1 soil, pH 8.3) inoculated with Glomus fasciculatum, Glomus intraradices, and Glomus macrocarpum to determine effects of vesicular-arbuscular mycorrhizal fungi (VAMF) species on plant growth and mineral nutrient uptake. Sorghum root colonization by VAMF and plant responses to Glomus species were temperature dependent. G. macrocarpum colonized sorghum roots best and enhanced plant growth and mineral uptake considerably more than the other VAMF species, especially at 30°C. G. fasciculatum enhanced shoot growth at 20 and 25°C, and mineral uptake only at 20°C. G. intraradices depressed shoot growth and mineral uptake at 30°C. G. macrocarpum enhanced shoot P, K, and Zn at all temperatures, and Fe at 25 and 30°C above that which could be accounted for by increased biomass. Sorghum plant growth responses to colonization by VAMF species may need to be evaluated at different temperatures to optimize beneficial effects.

Effect of vesicular-arbuscular mycorrhizal fungi on Mn uptake by red clover

The effect of VA mycorrhizae on the uptake of Mn by red clover ( Trifolium pratense L.) was studied in a) three steam-sterilized soils uninoculated or inoculated with six compound inocula, and in b) an unsterilized soil treated as to obtain different soil-P levels. Results suggest that mycorrhizal symbioses depressed the uptake of Mn by red clover.

Effects of vesicular-arbuscular mycorrhizal fungi on heavy metal uptake by soybeans

The uptake of heavy metals by soybeans may be affected by the colonization of roots with vesicular-arbuscular mycorrhizal (VAM) fungi. Soils with various heavy metal contents were collected from areas in close proximity to a Zn smelter in operation for nearly 100 yr. All soils were placed into pots and steam sterilized. One treatment was inoculated with mixed VAM fungi (600 spores per pot) and soil bacteria. The second treatment was inoculated with soil bacteria (minus VAM fungi) and the third treatment remained sterile. Soybeans ( Glycine max L. Merr. “Essex”) were sown into each soil. After 6 weeks of growth, the plants were harvested and the dry weight and the content of N, P, Zn, Cd, Cu, Mn and Fe were determined in plant leaves. The amount of VAM fungal colonization, nitrogenase activity and number and weight of nodules were also determined on plant roots. Results indicate that inoculation with soil bacteria and VAM fungi increased plant dry weight and foliar P and N contents. Inoculation with VAM fungi reduced Zn, Cd and Mn concentrations in plant leaves grown in soil with high concentrations of these metals. VAM fungi enhanced foliar concentrations of these heavy metals when the plants were grown in soils with low heavy metal concentrations. The colonization of roots by VAM fungi was reduced at the highest soil metal concentrations. These results indicate that the effect of VAM fungi on heavy metal uptake is dependent upon the initial soil metal concentration.

Glycine-Glomus-Rhizobium Symbiosis

Soybean (Glycine max [L.] Merr.) plants were nodulated (Bradyrhizobium japonicum) and either inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe or left uncolonized. All plants were grown unstressed for 21 days initially. After this period, some VAM and non-VAM plants were exposed to four 8-day drought cycles while others were kept well watered. Drought cycles were terminated by rewatering when soil moisture potentials reached -1.2 megapascal. Nodule development and activity, transpiration, leaf conductance, leaf and root parameters including fresh and dry weight, and N and P nutrition of VAM plants and of non-VAM, P-fed plants grown under the same controlled conditions were compared. All parameters, except N content, were greater in VAM plants than in P-fed, non-VAM plants when under stress. The opposite was generally true in the unstressed comparisons. Transpiration and leaf conductance were significantly greater in stressed VAM than in non-VAM plants during the first half of the final stress cycle. Values for both VAM and non-VAM plants decreased linearly with time during the cycle and converged at a high level of stress (-1.2 megapascal). Effects of VAM fungi on the consequences of drought stress relative to P nutrition and leaf gas exchange are discussed in the light of these findings and those reported in the literature.

Effects of VAM and reduced nutrient availability on growth and phosphorus and micronutrient uptake of wheat and field beans under greenhouse conditions

The effect of vesicular-arbuscular mycorrhizal fungi (VAM) on field bean and spring wheat dry matter production and on phosphorus, zinc, copper, iron and manganese uptake was determined under greenhouse conditions. Nutrient availability was varied by using different sizes of pots and by diluting the soil with sand. VAM increased plant dry matter production under all sets of growth conditions. VAM were found to directly increase the uptake of P, Zn, Cu and Fe by field beans and of P and Zn for wheat in both experiments. Increased uptake of the other nutrients measured was attributed to increased dry matter production or other factors. The effect of VAM decreased as the pot size holding the host plants decreased, but was not affected by the ratio of soil to sand if the pot size was kept constant. Nutrient uptake by beans as a proportion of total amount of nutrient present increased as the amount of nutrient decreased. Increase in root-soil contact and altered chemical equilibria are probable reasons for increased efficiency of nutrient uptake by beans as the level of available nutrient decreased. For wheat, which has a relatively fibrous root system, decreasing the nutrient availability had minimal effects on nutrient uptake in these experiments. Increases in total uptake of a particular nutrient resulting from inoculation with VAM are not necesarily indicative of a direct uptake of that nutrient by the VAM.

Do Mycorrhizae Influence the Drought Tolerance of Citrus?

The benefits of vesicular-arbuscular mycorrhizal (VAM) fungi for increasing drought tolerance have been demonstrated under nutrient-limiting conditions, particularly in low phosphorus (P) soils. Horticultural plants grown in soilless media, under greenhouse fertilizer regimes, are usually non-mycorrhizal, but have optimum P and the desired size and nutritional characteristics available when transplanted. Since plant nutrition can influence responses to environmental stress, potential benefits of VAM fungi for reducing transplant stress, such as drought, should be evaluated where growth and nutrition of mycorrhizal and non-mycorrhizal plants are similar at time of outplanting. In this way, nutritional and any unique non-nutritional effects of mycorrhizae on stress tolerance of plants can be identified. Non-nutritional effects of VAM fungi on drought tolerance of woody horticultural plants have not yet been clearly demonstrated.

Effects of Vesicular-Arbuscular Mycorrhizal Fungi on Infection of Tamarillo (Cyphomandra betacea) by Meloidogyne incognita in Fumigated Soil

Effects of Vesicular-Arbuscular Mycorrhizal Fungi on Infection of Tamarillo (Cyphomandra betacea) by Meloidogyne incognita in Fumigated Soil

Effect of vesicular-arbuscular mycorrhizal fungi and phosphate-solubilizing bacteria on growth and nutrition of soybean in a neutral-calcareous soil amended with32P-45Ca-tricalcium phosphate

The interactions between vesicular-arbuscular (VA) mycorrhiza and phosphate-solubilizing bacteria (PSB) on the utilization of the sparingly soluble32P-45Ca-tricalcium phosphate byGlycine max-Rhizobium japonicum was studied in a neutral calcareous soil. Two mycorrhizal endophytes,Glomus mosseae and aGlomus sp. (E3), were assayed. Both of them increased plant growth and nutrition, E3 being the most efficient. Mycorrhizal inoculation, especially with E3, improved plant utilization of the sparingly soluble tricalcium phosphate. However, the proportion of P in the plant shoots derived from the fertilizer was lower in mycorrhizal plants. Although PSB inoculation did not improve fertilizer utilization by either roots or mycorrhizas, it did produce an increase in shoot N concentration and content, and in the shoot to root ratio. The amount of mycorrhizal infection was also increased by PSB at all levels of added phosphate.