Infectivity of vesicular arbuscular mycorrhizal fungi in agricultural soils

1982 ◽  
Vol 33 (6) ◽  
pp. 1049 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Soil Properties ◽  
Mycorrhizal Fungi ◽  
Agricultural Soils ◽  
Subterranean Clover ◽  
Phase Iii ◽  
Poor Correlation ◽  
Lag Phase ◽  
Vesicular Arbuscular ◽  
Field Soils ◽  
Va Mycorrhizal Fungi

The development of vesicular arbuscular (VA) mycorrhizas was followed for subterranean clover grown in 20 field soils in a glasshouse experiment. The aims of the study were: to understand the way in which mycorrhizas develop in field soils; to identify those factors which could be used to predict field sites suitable for inoculation with VA mycorrhizal fungi. In each soil, the amount and rate of mycorrhiza formation were estimated for species of each genus represented. The data were examined in relation to differences among soils in numbers of spores of VA mycorrhizal fungi and in soil properties. A poor correlation between total spore numbers and the total amount and rate of infection formed was attributed to two factors. First, infection by fine endophyte (a fungus which does not form large spores that can be counted) was ubiquitous, but the amount of mycorrhizas formed by this fungus varied greatly. Second, species of fungi differed in their rates of infection. In general, there was an association between spore numbers and infection development for individual fungal species. The development of mycorrhizas in any soil fell into one of three categories: I, rapid and extensive; II, extensive but with a lag phase; III, slow and limited in extent. The species of fungi in soils from each category were similar. Category I included the soils which were most deficient in phosphorus for plant growth. However, from measurements of soil properties alone, it is not possible to predict those soils which are suitable for the introduction of inoculant VA mycorrhizal fungi.

Introduction of vesicular arbuscular mycorrhizal fungi into agricultural soils

1983 ◽  
Vol 34 (6) ◽  
pp. 741 ◽  
Author(s):  
LK Abbott ◽  
AD Robson ◽  
IR Hall
Keyword(s):  
Mycorrhizal Fungi ◽  
Agricultural Soils ◽  
Subterranean Clover ◽  
Arbuscular Mycorrhizal ◽  
Temporary Increase ◽  
Indigenous Species ◽  
Previous Survey ◽  
Rate Of Development ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

Two species of vesicular arbuscular (VA) mycorrhizal fungi were introduced into agricultural soils at four field sites. Three sites were chosen, on the basis of a previous survey, to give a range in the expected extent and rate of mycorrhizal formation by the indigenous fungi. The fourth site had recently been cleared of natural vegetation and ploughed. The success of inoculation with Glomus fasciculatum and G. monosporum was measured by estimating the extent of mycorrhizas formed by the inoculant fungi and by recording growth of subterranean clover. The effects of inoculating with these two mycorrhizal fungi on the development of mycorrhizas formed by the indigenous fungi were also followed in detail. At two sites, infection by G. fasciculatum was increased in the plots where this species was added in the inoculum. Growth was temporarily enhanced after inoculation with G. fasciculatum at one of these sites. This corresponded with a temporary increase in the percentage of root length infected as a result of inoculation. Plants grown at the two sites where G. fasciculatum became established had a slower rate of development of infection by the indigenous VA mycorrhizal fungi compared with that formed by the indigenous species at the other two sites.

The role of vesicular arbuscular mycorrhizal fungi in agriculture and the selection of fungi for inoculation

1982 ◽  
Vol 33 (2) ◽  
pp. 389 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Plant Growth ◽  
Nutrient Uptake ◽  
Mycorrhizal Fungi ◽  
Large Scale ◽  
Agricultural Soils ◽  
Va Mycorrhizas ◽  
Vesicular Arbuscular ◽  
Field Soils ◽  
Va Mycorrhizal Fungi ◽  
Mycorrhizal Roots

Vesicular arbuscular (VA) mycorrhizas are roots infected with particular soil fungi which form symbiotic associations. It is often assumed that VA mycorrhizal fungi could be used to increase the efficiency of phosphate fertilizers in agriculture. Our principal concern is the question: 'Can the symbiosis be exploited on a large scale?'. VA mycorrhizas increase nutrient uptake, and hence plant growth, by shortening the distance that nutrients must diffuse through soil to the root. Mycorrhizal roots do not appear to have a lower threshold concentration of nutrients for absorption from solution than do non-mycorrhizal roots. Most soils contain VA mycorrhizas. Hence, for plant growth to respond to inoculation with VA mycorrhizal fungi, agricultural soils must have either a low incidence of indigenous VA mycorrhizal fungi or alternatively, species which are less effective than the inoculant fungi in their ability to stimulate nutrient uptake by plants. The distribution of species of VA mycorrhizal fungi varies with climatic and edaphic environment, as well as with land use. However, the factors which control their distribution are poorly understood. Differences among VA mycorrhizal fungi in their ability to increase nutrient uptake appear to be due to differences in their ability to form mycorrhizas rapidly and extensively. The importance of other differences among the fungi, such as in the absorption of nutrients from solution or in the distribution and amount of external mycelium, has yet to be clearly demonstrated. Inoculant VA mycorrhizal fungi must be capable of persisting in soils at a high inoculum potential, as well as being able to increase nutrient uptake. Until now, little attention has been paid to characteristics which enable the fungi to persist after inoculation. We are critical of many of the methods employed in experiments aimed at selecting 'efficient' VA mycorrhizal fungi. For practical purposes, selection can only be achieved by means of comparisons performed in untreated field soils, with phosphorus supply limiting plant growth. Because the form of inoculum can affect the relative abilities of VA mycorrhizal fungi to infect and improve plant growth, appropriate inocula are needed for each agricultural situation. The survival of many species of fungi in various types of inocula requires further study so that procedures can be developed for introducing particular fungi into agricultural soils. This review emphasizes many gaps in our knowledge. For example, we need more information on how and to what extent species or strains of VA mycorrhizal fungi differ in their ability to increase plant growth. We know even less about their beneficial effects in years following that of field inoculation. The ecology of indigenous VA mycorrhizal fungi in field soils has also been largely neglected. These and other deficiencies preclude any immediate recommendations for large-scale inoculation with selected VA mycorrhizal fungi.

The effect of soil pH on the formation of VA mycorrhizas by two species of Glomus

Soil Research ◽  
1985 ◽  
Vol 23 (2) ◽  
pp. 253 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Soil Ph ◽  
Mycorrhizal Fungi ◽  
Subterranean Clover ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi ◽  
Four Levels ◽  
Ph Level ◽  
Ph Range ◽  
Spread Of Infection ◽  
Glomus Sp

Two species of vesicular-arbuscular (VA) mycorrhizal fungi differed in their ability to infect subterranean clover roots when soil pH was changed by liming. In a glasshouse experiment, Glomus fasciculatum infected extensively at each of four levels of soil pH (range 5.3-7.5). Glomus sp. (WUM 16) only infected extensively at the highest pH level. Liming the soil depressed plant growth, but this effect was almost entirely overcome by inoculation with G. fasciculatum. In the second experiment, Glomus sp. (WUM 16) failed to spread from existing infection within roots of subterranean clover when soil pH was 5.3 or lower. The lack of spread of infection was associated with an inability of hyphae of this fungus to grow in the soil used unless it was limed to give a pH at least greater than 5.3.

The Effect of Surface Mining on the Infectivity of Vesicular-Arbuscular Mycorrhizal Fungi

1987 ◽  
Vol 35 (6) ◽  
pp. 641 ◽  
Author(s):  
DA Jasper ◽  
AD Robson ◽  
LK Abbott
Keyword(s):  
Mycorrhizal Fungi ◽  
Surface Mining ◽  
Subterranean Clover ◽  
Arbuscular Mycorrhizal ◽  
Mining Operation ◽  
Soil Disturbance ◽  
Inoculum Potential ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi ◽  
Mine Sites

We tested the hypothesis that soil disturbance associated with mining will reduce the infectivity of propagules of vesicular-arbuscular (VA) mycorrhizal fungi to different extents, depending on the mining operation and the environment. At each of four mine sites, the infectivity of VA mycorrhizal fungi was estimated in soil from native vegetation, disturbed topsoil and revegetated soil. Infectivity was measured using subterranean clover and Acacia species as bioassay plants. In a second experiment the effects of soil disturbance and soil storage on infectivity of VA mycorrhizal fungi were measured separately. Topsoil disturbance decreased the number of spores or the number of spore types that could be isolated from the soil, and reduced or delayed formation of VA mycorrhizas. Glasshouse treatments indicated that both disturbance and a period of storage without plant growth contributed to the loss in infectivity of propagules of VA mycorrhizal fungi. After 4-5 years of revegetation, the number of infective propagules appears to be restored to a level equivalent to that of undisturbed soils. The possibility of improving revegetation by increasing the inoculum potential of disturbed soils needs to be investigated.

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.

Tripartite associations in snowbrush (Ceanothus velutinus): effect of vesicular–arbuscular mycorrhizae on growth, nodulation, and nitrogen fixation

1981 ◽  
Vol 59 (1) ◽  
pp. 34-39 ◽  
Author(s):  
S. L. Rose ◽  
C. T. Youngberg
Keyword(s):  
Host Plant ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Nitrogenase Activity ◽  
Mycorrhizal Fungus ◽  
Nodule Formation ◽  
Nitrogen Fixing ◽  
Symbiotic Associations ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

Symbiotic associations were established between nitrogen-fixing nonleguminous (actinorrhizal) snowbrush (Ceanothus velutinus Dougl.) seedlings and two categories of microorganisms: vesicular–arbuscular (VA) mycorrhizal fungi and a filamentous actinomycete capable of inducing nodule formation. The actinomycete is housed in nodules where fixation of atmospheric dinitrogen occurs and is made available to the host plant; the mycorrhizal fungus is both inter- and intra-cellular within the root tissue and may be found within the nodules. The two major nutrients, N and P, are made available and can be supplied to the host plant by these two symbiotic microorganisms. The root system of snowbrush seedlings was dually colonized by VA mycorrhizal fungi and a nitrogen-fixing actinomycete and the possibility of a direct interaction between the endophytes in the symbioses was investigated. Dually infected plants showed increases in total dry weight of shoots and roots, number of nodules, weight of nodular tissue, as well as higher levels of N, Ca2+, and P, and an increase in nitrogenase activity as measured by acetylene reduction.

Vesicular–arbuscular mycorrhiza influence growth but not mineral concentrations in seedlings of eight sweetgum families

1979 ◽  
Vol 9 (2) ◽  
pp. 218-223 ◽  
Author(s):  
R. C. Schultz ◽  
P. P. Kormanik ◽  
W. C. Bryan ◽  
G. H. Brister
Keyword(s):  
Arbuscular Mycorrhiza ◽  
Nutrient Uptake ◽  
Mycorrhizal Fungi ◽  
Growing Season ◽  
Initial Growth ◽  
Soil Mixture ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi ◽  
Mineral Concentrations

Seedlings of eight half-sib sweetgum (Liquidambarstyraciflua L.) families were grown for 6 months in a fumigated soil mixture, with or without inoculum from a mixture of Glomusmosseae and Glomusetunicatus fungi, at levels of 140, 280, 560, and 1120 kg/ha of 10–10–10 fertilizer. All seedlings received three additions of 187 kg/ha of N during the growing season. Inoculated seedlings had significantly greater biomass, height, and stem diameters at each fertilizer level than nonmycorrhizal control seedlings. Significant differences in growth occurred between families in mycorrhizal plants. However, fertilizer did not significantly affect growth or nutrient uptake of the seedlings. Inoculation with VA mycorrhizal fungi did not increase N, P, K, or Mg concentrations in the leaves, stems, or roots. Leaves of VA mycorrhizal seedlings had higher concentrations of calcium but stems and roots had lower concentrations of this element than the nonmycorrhizal seedlings. Seedlings with endomycorrhizae contained higher absolute quantities of each nutrient simply because of their greater biomass. The results suggest that the role of VA mycorrhizal fungi in the initial growth of sweetgum seedlings may be the result of physiological stimuli other than increased nutrient uptake.

Seasonal variation in infectivity of vesicular-arbuscular mycorrhizal fungi in relation to plant response to applied phosphorus

Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 207 ◽  
Author(s):  
NS Bolan ◽  
LK Abbott
Keyword(s):  
Seasonal Variation ◽  
Plant Growth ◽  
Soil Sample ◽  
Mycorrhizal Fungi ◽  
Response Curve ◽  
Subterranean Clover ◽  
Arbuscular Mycorrhizal ◽  
Mycorrhizal Infection ◽  
Virgin Forest ◽  
Vesicular Arbuscular

The effect of applied phosphorus on the growth of subterranean clover was studied in a virgin forest soil sample collected in summer and again in spring. The soil sample was used soon after it was collected. The shape of the response curve for plant growth differed greatly in the two experiments. This may be related to the presence of vesicular-arbuscular mycorrhizal infection in plants grown in the soil sample collected in summer and its absence in the soil sample collected in spring.

The Distribution and Abundance of Vesicular Arbuscular Endophytes in Some Western Australian Soils

1977 ◽  
Vol 25 (5) ◽  
pp. 515 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Soil Properties ◽  
Soil Ph ◽  
Western Australia ◽  
Agricultural Soils ◽  
Soil Samples ◽  
Root Infection ◽  
Spore Type ◽  
Va Mycorrhizas ◽  
Vesicular Arbuscular ◽  
Western Australian

The distribution and abundance of large-spored vesicular arbuscular (VA) endophytes was examined at three localities in Western Australia. Within each locality, soil samples were collected from sites with a range of soil properties and superphosphate histories. Vesicular arbuscular endophytes were widespread. Spores were found in all but five of 104 samples. In two of the samples where spores were not found, plants grown in the soils formed VA mycorrhizas. Root infection by a fine endophyte resembling Rhizophagus tenuis was also frequently observed. Five spore types were found. Honey-coloured sessile spores were present in 85% of the samples. The yellow vacuolate spore type was the second most common endophyte, but its distribution was mostly limited to cultivated and fertilized soils. Endophytes other than the yellow vacuolate spore type occurred on both virgin and agricultural soils. The distribution of honey-coloured sessile and yellow vacuolate spores in cultivated soils appeared to be associated with variation in soil pH. The total numbers of spores collected on a 106 μm sieve were not correlated with soil pH, NaHCO3-extractable phosphorus or superphosphate history.

Sign in / Sign up

Export Citation Format

Share Document