VA Mycorrhizal Research Articles

Distribution of VA mycorrhizal endophytes amongst plants from a Danish grassland community

Roots from four co-occurring plant species were examined for the infection anatomy of their VA mycorrhizal (VAM) endophytes at three harvests. From the same location, roots from seven plant species were used to inoculate cucumber plants ( Cucumis sativus L.). The endophytes recovered on these bait plants were characterized on the basis of their isozyme pattern after polyacrylamide gelelectrophoresis (PAGE). The presence of particular groups of endophytes was dependent on the host plant and the harvest time. Difference in isozyme pattern from the bait plants indicates that different plant species, although growing together, may not share VAM endophytes.

Colonization of Strawberry Roots by VA Mycorrhizal Fungi in Agroecosystems under Conventional and Transitional Organic Management

ABSTRACT Mycorrhizal colonization of strawberry roots was studied for two agricultural management systems on the California central coast, one conventional and one in transition to organic. Low levels of VAM colonization early in the first year of the experiment may be the result of past management practices, which included conventional production of a non-mycorrhizal crop with high levels of phosphorus inputs. In the second year colonization levels were higher in the transitional organic plots. Annual use of a fumigant and a fungicide in the conventional plots was implicated with depleting the VAM inoculum reservoir and maintaining low colonization levels. Inoculation of organically managed plots with Glomus intraradices at the second planting did not change colonization levels. Soil analyses showed that available soil phosphorus levels remained high (range 62 to 101 ppm) in both treatments throughout the study. In both years colonization increased during the spring and summer harvest season, and it is h...

Selection of Efficient VA Mycorrhizal Fungi for Trifoliate Orange

ABSTRACT Trifoliate orange (Poncirus trifoliata) is an important citrus rootstock but it has a slow growth rate. Eighteen different mycorrhizal fungi were screened for their symbiotic response with Trifoliate orange. Of the 18 fungi, G. velum (Nedlands), G. caledonicum (Nedlands), G. merredum (Nedlands), G. macrocarpum (Ruakuara) and Acaulospora sp. (ICRISAT) were found to be the best for improving growth and nutrition resulting in greater plant height, stem diameter, plant biomass, P, Zn and Cu content. All the five fungi selected were statistically equivalent in improving growth and nutrition of Trifoliate orange. Inoculation of the root stock with these fungi induced a stem girth of pencil thickness, i.e. ready for budding in 14–15 months in contrast to 22–24 months without mycorrhizal inoculations, thus saving about 8–9 months.

Effects of vesicular‐arbuscular mycorrhizas and phosphorus on water status and growth of apple

Abstract Apple (Malus hupehensis Rehd) seedlings were grown in sterilized and non‐sterilized soil with or without phosphorus (P) added and inoculated by VA mycorrhizal (VAM) fungi (Glomus versifome Daniels et Tappe and Glomus macrocarpum Tul et Tul). In sterilized soil, the VAM infection increased the transpiration rate (Tr.) of the leaves, reduced the stomatal resistance (Sr.) and the permanent wilting percentage (PWP) and enhanced the rate of recovery of the plant from the water stress and the plant growth (e.g. leaf number, stem diameter and dry weight). It also increased absorption of most minerals, especially Zn and Cu by the roots and weakened the P‐Cu and P‐Zn interactions. Phosphorus fertilization had some positive effects on the water status, P nutrition and growth, but it reduced the Cu concentration. VAM improved the water status and enhanced drought tolerance of the trees by enhancing absorption and translocation of water by the external hyphae. The efficiency of inoculation in nonsterile soil...

Influence of phosphorus level on VA Mycorrhizal colonization and growth of cowpea cultivars

Vesicular-arbuscular mycorrhizal (VAM) associations often vary according to the abundance of available soil phosphorus (P). Therefore, understanding the response of crop plants to colonization by VAM fungi necessitates the study of the response of colonized and noncolonized plants, from a range of cultivars, to differing levels of P. Cowpea is grown throughout the world, often on impoverished soils in which it can benefit from formation of mycorrhizae. The present study was conducted to determine the response of four cultivars of cowpea (Vigna unguiculata (L.) Walp.), varying in nitrogen fixation capacity, to inoculation withGlomus fasciculatum at four levels of added P in the rooting medium. In a greenhouse experiment, four cowpea cultivars, Mississippi Silver, Brown Crowder, Six Week Browneye and MI 35, were grown with and without the mycorrhizal fungus at four levels of added P, 0, 10, 20 and 30 ppm. Root colonization (%) was negatively correlated with P content of the growth medium and shoot P concentration. Intraspecific variability was shown for shoot dry weight and leaf area in response to inoculation withG. fasciculatum at different P levels. The range of P required in the growth medium which allowed benefit fromG. fasciculatum was identified for individual cultivars using shoot dry weight and leaf area, and collectively across cultivars for other parameters.

Gas‐chromatographic Separation of Organic Acids and Electrophoretic Determination of Phosphatases from VA Mycorrhizal Roots

AbstractA report is given on methods for separation and identification of organic acids, including phenolic acids, and on the determination of phosphatases from VA mycorrhizal (VAM) roots.For gas‐chromatographic preparation of the samples containing the organic acids silylation and methylation were tested, as well as various solvents and silylating reagents. Columns of different polarity were examined for their separation properties. Gas‐ chromatographic separation of the acids was incomplete on the packed column OV 7. With the capillary column PVMS 54 separation was much better, but improvements are still needed.Mycorrhiza‐specific phosphatases (MSP) appearing as three bands were found by electrophoresis with porosity‐gradient gels in mycorrhizal roots of Allium, Sorghum and Eupatorium plants. In these three species each MSP was located at the same position. Inoculated onion roots enzymatically digested with cellulase and pectinase showed no root‐specific phosphatases, but still revealed MSP. Further improvements in electrophoresis techniques are being investigated.

Charcoal as a Possible Inoculation Carrier for VA Mycorrhizal Fungi

Charcoal as a Possible Inoculation Carrier for VA Mycorrhizal Fungi

Water Relations of Red CloverTrifolium pratenseL. as Affected by VA Mycorrhizal Infection and Phosphorus Supply Before and During Drought

Water Relations of Red Clover<i>Trifolium pratense</i>L. as Affected by VA Mycorrhizal Infection and Phosphorus Supply Before and During Drought

The Activation of Dormant Spore in VA Mycorrhizal Fungi

The Activation of Dormant Spore in VA Mycorrhizal Fungi

THE DISTRIBUTION OF MYCORRHIZAS AMONG FAMILIES OF VASCULAR PLANTS.

From a literature search, information has been compiled on the mycorrhizal status under field conditions of 20 or more species in each of 25 families. The percentage of species which are mycorrhizal ranged from 100% in seven families to 8% in Cruciferae, many families having additional species that are sometimes mycorrhizal. No family in the list was consistently non-mycorrhizal. Apart from the Ericaceae, the families were either predominantly ectomycorrhizal or predominantly VA mycorrhizal. However, almost all families had at least one example of each of these mycorrhizal types.

Relationships between VA Mycorrhizal Fungi and Plant Cover following Surface Mining in Wyoming

Relationships between VA Mycorrhizal Fungi and Plant Cover following Surface Mining in Wyoming

Effects of VA-mycorrhizal fungi on growth and nutrient uptake of cuttings ofRosa multiflora in two container media with three levels of fertilizer application

Rooted cuttings ofRosa multiflora ‘Brooks 56’ were grown in a medium of 1 mineral soil: 1 sand (v/v) or bark: 1 sand (v/v) inoculated with the VA-mycorrhizal (VAM) fungiGlomus mosseae (Nicol. and Gerd.) Gerd. and Trappe andG. fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe or left as noninoculated controls. The slow release fertilizer osmocote was applied at rates of either 0, 1.2, or 4.2 kg/m3 (18N-6P-12K) and incorporated into the container medium. After 180 days plants were evaluated for growth, development and chemical leaf analysis. Greatest growth responses occurred after the highest fertilizer application of 4.2 kg/m3, and the poorest one after 0 kg/m3. Combination bark: sand medium was superior to mineral soil: sand medium for growth of mycorrhizal plants. At 0 kg/m3, mycorrhizal plants in bark: sand medium had longer shoots than other treatments. At 1.2 kg/m3, VAM plants compared to nonmycorrhizal plants in park:sand medium had greater effect on growth parameters. At the highest fertilizer application of 4.2 kg/m3, greatest growth responses occurred with VAM plants in bark:sand medium. Mycorrhizal plants compared to nonmycorrhizal plants in bark:sand medium had greater K and Zn uptake at 0 kg/m3, and greater K, Ca, S, Mn and Zn uptake at 1.2 kg/m3.

Improvement of the Sucrose Centrifugation Method for Counting of Spores of VA Mycorrhizal Fungi in Soil

Improvement of the Sucrose Centrifugation Method for Counting of Spores of VA Mycorrhizal Fungi in Soil

Distribution of VA Mycorrhizal Fungi along a Latitudinal Temperature Gradient

Distribution of VA Mycorrhizal Fungi along a Latitudinal Temperature Gradient

Osmotic Adjustment in Leaves of VA Mycorrhizal and Nonmycorrhizal Rose Plants in Response to Drought Stress

Osmotic adjustment in Rosa hybrida L. cv Samantha was characterized by the pressure-volume approach in drought-acclimated and unacclimated plants brought to the same level of drought strain, as assayed by stomatal closure. Plants were colonized by either of the vesicular-arbuscular mycorrhizal fungi Glomus deserticola Trappe, Bloss and Menge or G. intraradices Schenck and Smith, or were nonmycorrhizal. Both the acclimation and the mycorrhizal treatments decreased the osmotic potential (Psi(pi)) of leaves at full turgor and at the turgor loss point, with a corresponding increase in pressure potential at full turgor. Mycorrhizae enabled plants to maintain leaf turgor and conductance at greater tissue water deficits, and lower leaf and soil water potentials, when compared with nonmycorrhizal plants. As indicated by the Psi(pi) at the turgor loss point, the active Psi(pi) depression which attended mycorrhizal colonization alone was 0.4 to 0.6 megapascals, and mycorrhizal colonization and acclimation in concert 0.6 to 0.9 megapascals, relative to unacclimated controls without mycorrhizae. Colonization levels and sporulation were higher in plants subjected to acclimation. In unacclimated hosts, leaf water potential, water saturation deficit, and soil water potential at a particular level of drought strain were affected most by G. intraradices. G. deserticola had the greater effect after drought preconditioning.

Hydrophylic Polymers as a Carrier for VA Mycorrhizal Inoculum

Four techniques of inoculating rooted Carissa grandiflora cuttings with the mycorrhizal fungus Glomus intraradices were evaluated. Placement of a root inoculum around the root systems of Carissa or totally incorporated into potting medium resulted in higher colonization levels than dipping cutting root systems in suspensions of inoculum in Viterra or Terrasorb hydrophyllic polymers. Growth responses, especially top dry weight, showed little difference among the inoculation techniques. Mycorrhizal mediated growth benefits for the tops were realized for all treatments. Storage of root inoculum for 12 weeks at 4.4°C (40 °F) had little effect on colonization levels by the fungus in Carissa roots.

Response of lentil to VA Mycorrhizal inoculation and plant available P levels of unsterile soils

Responses of lentil in unsterile soils at low, medium and high levels of plant available soil P toGlomus fasciculatum inoculation were evaluated. It was observed that growth, dry matter accumulation, nodulation, and nitrogen fixation were considerably improved in VAM inoculated plants over uninoculated control at low and medium levels of plant available soil P.

The Effect of VA Mycorrhizal Infection and Phosphorus Status on Sunflower Hydraulic and Stomatal Properties

Koide, R. 1985. The effect of VA mycorrhizal infection and phosphorus status on sunflower hydraulic and stomatal properties.—J. exp. Bot. 36: 1087–1098. Mycorrhizal (M) and non-mycorrhizal (NM) sunflower plants were grown in a soil of low phosphorus availability (with and without phosphorus amendment) and in a soil of moderate phosphorus availability (without phosphorus amendment). Using the Ohm's law analogy and measured leaf water potentials, stem water potentials, and transpiration rates, hydraulic resistances were calculated for the whole plant, leaf, and below leaf components. Mycorrhizal infection (as high as 89%) was shown to have no effect on the intrinsic hydraulic properties of the soil/plant system over a wide range of transpiration rates in either soil when M and NM plants of equivalent root length were compared. When grown in the soil of moderate phosphorus availability, calculated hydraulic resistances under given environmental conditions were the same for M and NM plants, as were stomatal resistances and transpiration rates. When grown in the soil of low phosphorus availability, calculated values of hydraulic resistance were lower for M plants than for NM plants under given sets of environmental conditions. These differences in calculated hydraulic resistance were not due to a difference in the intrinsic hydraulic properties of M and NM plants. The differences were evident because stomatal resistances were lower and transpiration rates higher for M plants and because hydraulic resistance varied inversely with transpiration rate. When plants of significantly greater root length were compared to plants of lesser root length, the calculated hydraulic resistances under given environmental conditions were much lower for the plants of greater root length. This difference was largely due to a difference in the intrinsic hydraulic properties between large and small plants, and not because of differences in transpiration rate. The elevated transpiration rates exhibited by M plants were attributed to an enhanced phosphorus status. Short term phosphorus amendments made to phosphorus-deficient NM plants improved transpiration; transpiration rates were similar for M and NM plants before NM plants became phosphorus-deficient, and phosphorus-amended M and NM plants had similar transpiration rates. The data are discussed in relation to other reports of mycorrhizal influence on hydraulic and stomatal resistances. Possible mechanisms for the influence of infection on stomatal resistance are also briefly discussed.

Potentials and limitations of mycorrhizal inoculation illustrated by experiments with field-grown cassava

Field inoculation trials with cassava (Manihot esculenta Crantz) were conducted in Quilichao (typic Dystropept soil) and Carimagua (Haplustox soil). In Quilichao, with a large and effective native VA-mycorrhizal (VAM) population, inoculation withGlomus manihotis did not increase cassava yields significantly, neither when different sources and levels of inoculum material were used, nor with different cassava cultivars, or after stabilizing soil temperature through mulching. Field inoculation did result in a decrease of the coefficient of variation with respect to yield. The high dependency of cassava on an effective VAM association was indicated by a marked decrease in yield after eradication of native VAM by soil sterilization. In Carimagua, with a lower native VAM population, mycorrhizal inoculation withG. manihotis increased yields significantly at intermediate levels of 100 kg/ha of applied P, using either inoculum of cassava orPanicum maximum roots or inoculum of a soil-root mixture of maize or tropical kudzu. Higher or lower levels of P decreased the effect of inoculation on yield. There were no significant differences among P sources, ranging from highly soluble triple superphosphate to low solubility rock phosphates. Inoculation with different VAM isolates had a variable effect on cassava yields, and showed that there may be an interaction between P fertilizer level and isolate efficiency. It is concluded that there may be a potential to increase yields or decrease the fertilizer P requirements of cassava through field inoculation with effective VAM isolates, in the vast areas of acid infertile Oxisols and Ultisols with low native VAM fungal populations, represented by Carimagua.

Selection of an Efficient VA Mycorrhizal Fungus for Finger Millet

Summary Response of three cultivars of finger millet to inoculation with three selected local mycorrhizal fungi, M2, M6, and M14, and Glomus fasciculatum obtained from USA, was studied under glasshouse conditions in order to select the most efficient mycorrhizal fungus for finger millet. The local isolate M6 was found to be the best in improving growth and P, K, Zn, Mn, and Cu and Fe nutrition of finger millet. Of the three cultivars studied cv Indaf-5 responded best to mycorrhizal inoculation.