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 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.

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.

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.

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.

Infectivity and effectiveness of vesicular arbuscular mycorrhizal fungi: effect of inoculum type

1981 ◽  
Vol 32 (4) ◽  
pp. 631 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Root Length ◽  
Mycorrhizal Fungi ◽  
Early Stage ◽  
Phosphorus Uptake ◽  
Subterranean Clover ◽  
Arbuscular Mycorrhizal ◽  
Large Numbers ◽  
Infected Root ◽  
Vesicular Arbuscular ◽  
Inoculum Type

Plants, inoculated with four vesicular arbuscular mycorrhizal (VAM) fungi (Glomus fasciculatus, G. monospovus and two isolates of Acaulospova laevis), were grown from 4 to 16 weeks, and the development of infection and spores was followed. Infected roots from pot cultures of different ages were used to examine the effect of mycorrhiza development on the infectivity of each fungus. The effectiveness of each fungus was assessed by measuring its ability to increase the growth of subterranean clover on a phosphate-deficient soil. For all fungi, the percentage of root length infected increased rapidly up to 10 weeks after sowing, and thereafter it either increased only slightly or decreased. Infectivity of root inocula increased with increasing percentage of root length infected in the inoculum for all fungi, except where large numbers of mature spores (24/g infected root) had been produced by one isolate of A. laevis. The infectivity of inoculum roots from pots containing mature spores of this isolate declined rapidly, although it was not decreased by the onset of sporulation by A. laevis. For all fungi, irrespective of the inoculum used, the fresh weight of tops of subterranean clover grown on a phosphate-deficient soil was very closely correlated with the percentage of its root length infected at an early stage of plant growth. That is, the effectiveness of the species of fungi examined at increasing phosphorus uptake into plants was related to the infectivity of the inoculum used.

Ecological consequences of arthropod grazing on VA mycorrhizal fungi

1988 ◽  
Vol 94 ◽  
pp. 25-32 ◽  
Author(s):  
T. P. McGonigle ◽  
A. H. Fitter
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Holcus Lanatus ◽  
Feeding Damage ◽  
Field Plot ◽  
Paper Briefly ◽  
Sterile Soil ◽  
Grassland Soil ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

SynopsisSoil Collembola may be partially responsible for observed reductions in effectiveness of vesicular-arbuscular mycorrhizal (VAM) associations in the field, compared with sterile soil experiments. Feeding damage to hyphae in soil is envisaged as a mechanism by which translocation of phosphorous from beyond root depletion zones to the plants is reduced. Previous work has demonstrated such effects in pots and in a cultivated field plot, and direct observation of feeding has been made. This paper briefly reviews this evidence and presents an experiment in which insecticide reduced the density of Collembola in a seminatural grassland soil, and increased phosphorus inflow into roots of Holcus lanatus. In addition, survey data are reported which show that hyphal grazing is ecologically feasible, as Collembola and infected roots are spatially associated with one another in the soil profile. It is suggested that hyphal grazing by these arthropods has important consequences for VAM function in natural vegetation systems.

Propagation and storage of vesicular–arbuscular mycorrhizal fungi isolated from Saskatchewan agricultural soils

1993 ◽  
Vol 71 (10) ◽  
pp. 1328-1335 ◽  
Author(s):  
Narayan C. Talukdar ◽  
James J. Germida
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Agricultural Soils ◽  
Gradient Centrifugation ◽  
Arbuscular Mycorrhizal ◽  
Triticum Aestivum L ◽  
Spore Production ◽  
Nutrient Stress ◽  
Vesicular Arbuscular Mycorrhizal Fungi ◽  
Vesicular Arbuscular

Factors affecting the propagation of vesicular–arbuscular mycorrhizal fungi (VAMF) Glomus clarum, Glomus mosseae, and Glomus versiforme isolated from Saskatchewan soils were assessed in growth-chamber studies. Initially, lentil (Lens esculenta L.), maize (Zea mays L.), and a sorghum (Sorghum bicolor (L.) Moench) and sudangrass (Sorghum sudanense (Piper) Hitch.) hybrid were inoculated with G. clarum and grown in 2 or 6 kg of soil–sand (1:1) substrate until maturity. All three crops supported growth and spore production by G. clarum, but the maize plant yielded the largest number of spores. The ability of G. clarum to produce large numbers of spores reflects either an inherent ability of this VAMF strain to sporulate or a favorable interaction (related to spore production) with a maize host crop. Twice as many G. clarum spores per gram of soil–sand substrate were obtained from 2-kg pots compared with 6-kg pots. Enhanced spore production in the smaller pots was related to poor plant growth and, apparently, nutrient stress. Plants grown in 2-kg pots were stunted, yielded less biomass, and exhibited severe symptoms of P and N deficiency. Monospecific cultures of G. clarum, G mosseae, and G. versiforme were produced using maize plants grown in 2-kg pots. Under these conditions the level of spore production was G. clarum > G. versiforme > G. mosseae. Storage of the VAMF inoculants at 7 °C, compared with 25 °C, enhanced spore viability. This was evident from a reduction in VAMF colonization and spore production in wheat (Triticum aestivum L.) and the sorghum–sudangrass hybrid plants inoculated with G. mosseae spores stored at 25 °C. Osmotic stress exerted on G. mosseae spores during density-gradient centrifugation had no effect on their viability. Key words: vesicular–arbuscular mycorrhizal fungi, Glomus spp., host crops, substrate mass, nutrient stress.

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