The influence of pH and nitrate on Mycorrhizal associations of Pinus radiata D. Don

1969 ◽  
Vol 17 (1) ◽  
pp. 59 ◽  
Author(s):  
C Theodorou ◽  
GD Bowen
Keyword(s):  
Pinus Radiata ◽  
Mycorrhizal Fungi ◽  
Alkaline Soils ◽  
Inhibition Of Growth ◽  
Mycorrhizal Associations ◽  
Mycorrhiza Formation ◽  
Nitrate Inhibition ◽  
Influence Of Ph ◽  
Cenococcum Graniforme ◽  
Rhizopogon Luteolus

Growth of 5-month-old Pinus radiata seedlings was 60-80% lower in soil at pH 8.0 than at pH 6.2. At pH 8.0 mycorrhiza formation was lower by c. 60% and ectotrophic mycorrhizas were compIetely replaced by ectendotrophic mycorrhizas. In a laboratory medium at pH 5.0, 575 p.p.m. nitrate did not depress growth of the mycorrhizal fungi Rhizopogon luteolus, Suillus granulatus, and Cenococcum graniforme, but at pH 8.0 growth was slight regardless of the nitrate concentration in the medium. Rhizosphere colonization by Rhizopogon luteolus was studied by comparing its growth along roots of P. radiata seedlings with that along glass fibres in sterile soil. At pH 5 .0 appreciable colonization of the root occurred but this was less with 115 p.p.m. than with 12 p.p.m. soil nitrate. Growth along fibres was significantly less than along roots. Alkalinity produced the most marked effect on colonization, there being no growth of R. luteolus along the root at pH 8.0 at both nitrate levels. It is concluded that decreased mycorrhiza formation in alkaline soils is caused by inhibition of growth of some mycorrhizal fungi in the rhizosphere in addition to possible nitrate inhibition of infection but nitrate inhibition of mycorrhiza formation under acid conditions is mainly due to inhibition of infection.

Influence of temperature on the mycorrhizal associations of Pinus radiata D. Don

1971 ◽  
Vol 19 (1) ◽  
pp. 13 ◽  
Author(s):  
C Theodorou ◽  
GD Bowen
Keyword(s):  
Pinus Radiata ◽  
Mycorrhizal Fungi ◽  
Linear Growth ◽  
Root Colonization ◽  
Fungal Species ◽  
Field Inoculation ◽  
Mycorrhizal Associations ◽  
Influence Of Temperature On ◽  
Soil Temperatures ◽  
Stimulate Plant Growth

The growth on Melin-Norkrans medium by 12 out of 13 isolates (five species) of mycorrhizal fungi declined rapidly between 20 and 16°C, as did colonization of the rhizosphere of Pinus radiata by four out of five isolates (three species). Mycorrhizal production in soil was optimal at 25° and declined markedly between 20 and 15°. Large differences occurred between strains within a fungal species in length of root colonized and in the intensity of growth on the root at 16°C. Extremely poor colonization by some fungi at 16° compared with 20° reveals a necessity to select fungi for field inoculation on the basis of root colonization at soil temperatures appropriate to the area and season as well as on ability to stimulate plant growth. The effect of tem- perature on the linear growth of different fungal isolates in a rich laboratory medium was a poor guide to their growth in the rhizosphere.

Vesicular–arbuscular endomycorrhizal associations of some desert plants of Baja California

1981 ◽  
Vol 59 (6) ◽  
pp. 1056-1060 ◽  
Author(s):  
Sharon L. Rose
Keyword(s):  
Mycorrhizal Fungi ◽  
Sonoran Desert ◽  
Baja California ◽  
Fungal Spores ◽  
Desert Plants ◽  
Endemic Plants ◽  
Mycorrhizal Associations ◽  
Glomus Spp ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

Endemic plants of the Sonoran Desert of Baja California were sampled for mycorrhizal associations. Eight of the 10 plant species examined were colonized by vesicular–arbuscular (VA) mycorrhizal fungi. Soil sievings revealed chlamydospores of three VA mycorrhizal Glomus spp.; G. microcarpus, G. fasciculatus, and G. macrocarpus. At the time of sampling, the populations of VA fungal spores in the soil were low, with one to five chlamydospores per 100 g soil sample.

Effect of root zone temperature on ectomycorrhiza and vesicular–arbuscular mycorrhiza formation in disturbed and undisturbed forest soils of southwest Oregon

1983 ◽  
Vol 13 (4) ◽  
pp. 657-665 ◽  
Author(s):  
Jennifer L. Parke ◽  
R. G. Linderman ◽  
J. M. Trappe
Keyword(s):  
Forest Soils ◽  
Mycorrhizal Fungi ◽  
Root Zone ◽  
Ectomycorrhizal Fungus ◽  
Root Zone Temperature ◽  
Clear Cut ◽  
Vesicular Arbuscular ◽  
Mycorrhiza Formation ◽  
Undisturbed Forest ◽  
Southwest Oregon

The presence of ectomycorrhizal and vesicular–arbuscular (VA) mycorrhizal fungi in soils from five sites in a mixed conifer zone in southwest Oregon, each consisting of a 1- to 1.5-year-old clear-cut adjacent to an undisturbed forest stand, was determined by bioassay with Pseudotsugamenziesii (Mirb.) Franco, Pinusponderosa Dougl. ex P. Laws & C. Laws, and Trifoliumsubterraneum L. 'Mt. Barker' as hosts grown at root zone temperatures ranging from 7.5 to 35 °C. Maximum formation of both ectomycorrhizae and VA mycorrhizae occurred at 18.5–24 °C in soils from all sites, and there were no significant qualitative or quantitative differences between disturbed (clear-cut) or undisturbed (forest) soils. Mycorrhiza formation was moderate even at the lowest temperature tested (7.5 °C) but was greatly reduced or prevented at or above 29.5 °C. Treatment of soil at 35 °C for 1 week did not appear to adversely affect viability of ectomycorrhizal fungus propagules, but young mycorrhizae subjected to the same treatment appeared to be severely injured. Thus the ability of native mycorrhizal fungi to grow at low soil temperatures is especially important as they may contribute to the survival of seedlings outplanted into climatic zones characterized by warm, dry summers following cool, wet winters and springs.

scholarly journals Specific mycorrhizal associations involving the same fungal taxa in common and threatened Caladenia (Orchidaceae): implications for conservation

2020 ◽  
Vol 126 (5) ◽  
pp. 943-955 ◽  
Author(s):  
Noushka Reiter ◽  
Ryan D Phillips ◽  
Nigel D Swarts ◽  
Magali Wright ◽  
Gareth Holmes ◽  
...  
Keyword(s):  
Threatened Species ◽  
Mycorrhizal Fungi ◽  
Sequence Divergence ◽  
High Specificity ◽  
Common Species ◽  
Geographic Range ◽  
Limiting Factor ◽  
Mycorrhizal Associations ◽  
Orchid Conservation ◽  
Australian Continent

Abstract Background and Aims In orchid conservation, quantifying the specificity of mycorrhizal associations, and establishing which orchid species use the same fungal taxa, is important for sourcing suitable fungi for symbiotic propagation and selecting sites for conservation translocation. For Caladenia subgenus Calonema (Orchidaceae), which contains 58 threatened species, we ask the following questions. (1) How many taxa of Serendipita mycorrhizal fungi do threatened species of Caladenia associate with? (2) Do threatened Caladenia share orchid mycorrhizal fungi with common Caladenia? (3) How geographically widespread are mycorrhizal fungi associated with Caladenia? Methods Fungi were isolated from 127 Caladenia species followed by DNA sequencing of the internal transcibed spacer (ITS) sequence locus. We used a 4.1–6 % sequence divergence cut-off range to delimit Serendipita operational taxonomic units (OTUs). We conducted trials testing the ability of fungal isolates to support germination and plant growth. A total of 597 Serendipita isolates from Caladenia, collected from across the Australian continent, were used to estimate the geographic range of OTUs. Key Results Across the genus, Caladenia associated with ten OTUs of Serendipita (Serendipitaceae) mycorrhizal fungi. Specificity was high, with 19 of the 23 threatened Caladenia species sampled in detail associating solely with OTU A, which supported plants from germination to adulthood. The majority of populations of Caladenia associated with one OTU per site. Fungal sharing was extensive, with 62 of the 79 Caladenia sampled in subgenus Calonema associating with OTU A. Most Serendipita OTUs were geographically widespread. Conclusions Mycorrhizal fungi can be isolated from related common species to propagate threatened Caladenia. Because of high specificity of most Caladenia species, only small numbers of OTUs typically need to be considered for conservation translocation. When selecting translocation sites, the geographic range of the fungi is not a limiting factor, and using related Caladenia species to infer the presence of suitable fungal OTUs may be feasible.

scholarly journals Productive and Physiological Response of Organic Potato Grown under Highly Calcareous Soils to Fertilization and Mycorrhization Management

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1200
Author(s):  
Sara Lombardo ◽  
Cristina Abbate ◽  
Gaetano Pandino ◽  
Bruno Parisi ◽  
Aurelio Scavo ◽  
...  
Keyword(s):  
Organic Farming ◽  
Mycorrhizal Fungi ◽  
Calcareous Soils ◽  
Arbuscular Mycorrhizal ◽  
Low Fertility ◽  
Soil Conditions ◽  
Alkaline Soils ◽  
Gas Exchange Parameters ◽  
Marketable Yield ◽  
Potato Growth

The enhancement of the actual low yields is the most important challenge regarding organic farming management. In this view, a valid tool may arise by the improvement of fertilization management and efficiency. In this regard, arbuscular mycorrhizal fungi (AMF) can play an important role, especially in low fertility soils such as calcareous ones, through a better nutrient uptake and by alleviating abiotic stresses. A replicated-space experiment was carried out to investigate the role of mycorrhizal-based inoculants combined with full or halved fertilizer doses on yield and physiological traits of three early potato cultivars organically grown in highly calcareous and alkaline soils. The results indicate that AMF symbiosis ameliorated, in comparison to the not-inoculated plants, the potato tolerance to limestone stress by enhancing the potential quantum efficiency of photosystem II (Fv/F0) and plant gas-exchange parameters (photosynthesis rate and stomatal conductance). Moreover, a significant improvement of marketable yield (+25%) was observed, mainly due to an increase of the number of tubers plant−1 (+21%) and, to a lesser extent, of average tuber weight (+10%). The AMF efficiency was higher applying halved fertilizer doses and in the location where soil conditions were unfavourable for potato growth. Moreover, the qRT-PCR highlighted that AMF colonization was similar in each location, demonstrating their tolerance to limestone, alkalinity and P stresses. These findings outlined that AMF are good candidate to bio-ameliorate calcareous soils and are very useful for improving potato yields under organic farming, limiting external fertilizers supply and environmental pollution.

scholarly journals Mycorrhizal Fungi Isolated from Native Terrestrial Orchids from Region of La Araucanía, Southern Chile

2020 ◽  
Vol 8 (8) ◽  
pp. 1120
Author(s):  
Hector Herrera ◽  
Tedy Sanhueza ◽  
Rodolfo Martiarena ◽  
Rafael Valadares ◽  
Alejandra Fuentes ◽  
...  
Keyword(s):  
Life Cycle ◽  
Seed Germination ◽  
Threatened Species ◽  
Mycorrhizal Fungi ◽  
Its Region ◽  
Southern Chile ◽  
Mycorrhizal Associations ◽  
Terrestrial Orchids ◽  
Recovery Strategies ◽  
Mycorrhizal Interactions

Mycorrhizal interactions of orchids are influenced by several environmental conditions. Hence, knowledge of mycorrhizal fungi associated with orchids inhabiting different ecosystems is essential to designing recovery strategies for threatened species. This study analyzes the mycorrhizal associations of terrestrial orchids colonizing grassland and understory in native ecosystems of the region of La Araucanía in southern Chile. Mycorrhizal fungi were isolated from peloton-containing roots and identified based on the sequence of the ITS region. Their capacities for seed germination were also investigated. We detected Tulasnella spp. and Ceratobasidium spp. in the pelotons of the analyzed orchids. Additionally, we showed that some Ceratobasidium isolates effectively induce seed germination to differing degrees, unlike Tulasnella spp., which, in most cases, fail to achieve protocorm growth. This process may underline a critical step in the life cycle of Tulasnella-associated orchids, whereas the Ceratobasidium-associated orchids were less specific for fungi and were effectively germinated with mycorrhizal fungi isolated from adult roots.

Mycorrhizae of Abies concolor in California

1977 ◽  
Vol 55 (10) ◽  
pp. 1345-1350 ◽  
Author(s):  
Isabel F. Alvarez ◽  
Fields W. Cobb Jr.
Keyword(s):  
Sierra Nevada ◽  
Mycorrhizal Fungi ◽  
Abies Concolor ◽  
North Central ◽  
Chemical Reagents ◽  
The North ◽  
Naturally Occurring ◽  
White Fir ◽  
Different Types ◽  
Cenococcum Graniforme

Nine different types of mycorrhizae were observed on naturally occurring white fir seedlings in the north central Sierra Nevada, including one formed by the ubiquitous Cenococcum graniforme. The macro- and micro-scopic characteristics and reactions to different chemical reagents are described for five types. Possible mycorrhizal fungi of white fir are listed. Nursery-grown seedlings examined were ectomycorrhizal; intracellular penetration was not observed. None of the naturally occurring mycorrhizal types were found on nursery seedlings.

Scientific approaches to Australian temperate terrestrial orchid conservation

2007 ◽  
Vol 55 (3) ◽  
pp. 293 ◽  
Author(s):  
Mark C. Brundrett
Keyword(s):  
Mycorrhizal Fungi ◽  
Three Dimensions ◽  
Natural Habitats ◽  
Mycorrhizal Associations ◽  
Terrestrial Orchids ◽  
Key Factor ◽  
Orchid Seed ◽  
Declining Populations ◽  
Feral Animals ◽  
Sexually Deceptive Orchids

This review summarises scientific knowledge concerning the mycorrhizal associations, pollination, demographics, genetics and evolution of Australian terrestrial orchids relevant to conservation. The orchid family is highly diverse in Western Australia (WA), with over 400 recognised taxa of which 76 are Declared Rare or Priority Flora. Major threats to rare orchids in WA include habitat loss, salinity, feral animals and drought. These threats require science-based recovery actions resulting from collaborations between universities, government agencies and community groups. Fungal identification by DNA-based methods in combination with compatibility testing by germination assays has revealed a complex picture of orchid–fungus diversity and specificity. The majority of rare and common WA orchids studied have highly specific mycorrhizal associations with fungi in the Rhizoctonia alliance, but some associate with a wider diversity of fungi. These fungi may be a key factor influencing the distribution of orchids and their presence can be tested by orchid seed bait bioassays. These bioassays show that mycorrhizal fungi are concentrated in coarse organic matter that may be depleted in some habitats (e.g. by frequent fire). Mycorrhizal fungi also allow efficient propagation of terrestrial orchids for reintroduction into natural habitats and for bioassays to test habitat quality. Four categories of WA orchids are defined by the following pollination strategies: (i) nectar-producing flowers with diverse pollinators, (ii) non-rewarding flowers that mimic other plants, (iii) winter-flowering orchids that attract fungus-feeding insects and (iv) sexually deceptive orchids with relatively specific pollinators. An exceptionally high proportion of WA orchids have specific insect pollinators. Bioassays testing orchid-pollinator specificity can define habitats and separate closely related species. Other research has revealed the chemical basis for insect attraction to orchids and the ecological consequences of deceptive pollination. Genetic studies have revealed that the structure of orchid populations is influenced by pollination, seed dispersal, reproductive isolation and hybridisation. Long-term demographic studies determine the viability of orchid populations, estimate rates of transition between seedling, flowering, non-flowering and dormant states and reveal factors, such as grazing and competition, that result in declining populations. It is difficult to define potential new habitats for rare orchids because of their specific relationships with fungi and insects. An understanding of all three dimensions of orchid habitat requirements can be provided by bioassays with seed baits for fungi, flowers for insects and transplanted seedlings for orchid demography. The majority of both rare and common WA orchids have highly specific associations with pollinating insects and mycorrhizal fungi, suggesting that evolution has favoured increasing specificity in these relationships in the ancient landscapes of WA.

Mycorrhizae, mycorrhizospheres, and reforestation: current knowledge and research needs

1987 ◽  
Vol 17 (8) ◽  
pp. 929-940 ◽  
Author(s):  
D. A. Perry ◽  
R. Molina ◽  
M. P. Amaranthus
Keyword(s):  
Environmental Factors ◽  
Mycorrhizal Fungi ◽  
Current Knowledge ◽  
Seedling Survival ◽  
Natural Populations ◽  
Tree Seedlings ◽  
Ecosystem Structure ◽  
Clear Cutting ◽  
Mycorrhiza Formation ◽  
Sphere Of Influence

Although not a panacea, management of mycorrhizae and associated organisms is an important reforestation aid. Its three major components are protection of the indigenous soil community and evaluation of inoculation needs, integration of inoculation programs into existing reforestation technology, and research. Clear-cutting frequently results in reduced mycorrhizae formation, particularly when reforestation is delayed and no other host plants are present to maintain fungal populations. Implications of such reductions for reforestation vary with environmental factors and tree species. Adequate mycorrhiza formation is especially critical for ectomycorrhizal trees growing on poor soils or in environments where seedlings must establish quickly to survive. It may also be important where early successional, noncrop plants do not support the same mycobiont as the crop. In such circumstances, a self-reinforcing trend may develop, with poor mycorrhiza formation reducing seedling survival and poor tree stocking leading to further loss of mycorrhizal inocula. Inoculating nursery seedlings with mycobionts holds promise for improving outplanting performance only if site-adapted fungi are used. A practical alternative is to improve nursery practices to enhance natural populations of mycorrhizal fungi. Seedlings leaving the nursery with diverse mycorrhizae may perform better than those leaving with only one or a few nursery-adapted types. Research is needed in three broad areas: on adaptations of mycorrhizal fungi to particular environmental factors; on interactions between tree seedlings and processes occurring within the sphere of influence of roots (the rhizosphere) or of mycorrhizal roots (the mycorrhizosphere); and on the role of mycorrhizae and associated organisms in ecosystem structure and processes, particularly nutrient cycling, plant-plant interaction, and soil structure.

The cooler side of mycorrhizas: their occurrence and functioning at low temperatures

2007 ◽  
Vol 85 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Mark Tibbett ◽  
John W.G. Cairney
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Mycorrhizal Fungi ◽  
Nutrient Acquisition ◽  
Significant Part ◽  
Freezing Resistance ◽  
Ecological Consequences ◽  
Cold Environments ◽  
Edaphic Conditions ◽  
Mycorrhizal Associations

Mycorrhizal associations occur in a range of habitats in which soils are subject to low temperature (≤15 °C) for a significant part of the year. Despite this, most of our understanding of mycorrhizal fungi and their interactions with their plant hosts is based on physiological investigations conducted in the range 20–37 °C using fungi of temperate origin. Comparatively little consideration has been given to the cold edaphic conditions in which many mycorrhizas survive and prosper, and the physiological and ecological consequences of their low temperature environments. In this review, we consider the distribution and persistence of arbuscular and ectomycorrhizal mycorrhizal associations in cold environments and highlight progress in understanding adaptations to freezing resistance and nutrient acquisition at low temperature in mycorrhizal fungi.

Sign in / Sign up

Export Citation Format

Share Document