Mycorrhizal Associations of Plant-Species in a Semiarid Community

1986 ◽  
Vol 34 (5) ◽  
pp. 585 ◽  
Author(s):  
P Mcgee
Keyword(s):  
Plant Species ◽  
South Australia ◽  
Growing Season ◽  
Arbuscular Mycorrhizas ◽  
Mycorrhizal Associations ◽  
Vesicular Arbuscular ◽  
Ectomycorrhizal Association

Of 93 species in 37 families occurring in a semiarid open mallee community near Murray Bridge, South Australia, 85 species were mycorrhizal. Vesicular-arbuscular mycorrhizas (VAM) were more common than other types of mycorrhizas observed. Genera not previously known to form ectomycorrhizas include Astroloma (Epacridaceae), Comesperma (Polygalaceae), Thysanotus (Asphodelaceae: Liliflorae), Baeckea and Calytrix (Myrtaceae), Dampiera (Goodeniaceae), Podotheca and Toxanthes (Inulae: Asteraceae). Many species were found with both ectomycorrhizas and VAM, with annuals having both VAM and ectomycorrhizas for the whole growing season and perennials usually exhibiting either a predominantly VAM or ectomycorrhizal association. Vesicles were present in plant species not commonly thought of as mycorrhizal hosts.

Studies on mycorrhizal associations in Harvard Forest, Massachusetts

1989 ◽  
Vol 67 (8) ◽  
pp. 2245-2251 ◽  
Author(s):  
Ruhama Berliner ◽  
John G. Torrey
Keyword(s):  
Plant Species ◽  
Most Probable Number ◽  
Probable Number ◽  
Harvard Forest ◽  
Mycorrhizal Associations ◽  
Monotropoid Mycorrhiza ◽  
Vesicular Arbuscular ◽  
Low Diversity ◽  
Different Types ◽  
Good Proportion

An estimate was made of the abundance of different types of mycorrhizal associations in two plant communities of conifers and hardwoods in the Harvard Forest. Lists of plant species, the coverage of their foliage in the canopy and understorey layers, and the types of mycorrhizal associations for 45 species common in these communities are presented. Of the species examined, 91 % were mycorrhizal, representing most of the known major types, viz. ectomycorrhiza, vesicular–arbuscular mycorrhiza (VAM), ericoid, and monotropoid mycorrhiza. Of the 45 species studied, 22% of the species showed ectomycorrhizal, and 71 % VAM associations. A direct spore count was a more reliable method than the most probable number method for determining VAM occurrence in the soil. Spore numbers ranged from 4.4 to 11.8 spores/g oven-dried soil. In conifer stands, ectomycorrhizae were most common, although VAM were also observed in the conifer species. In hardwood stands, VAM were more frequent than in conifer stands, but mycorrhizae were heterogeneous and included a good proportion of the ericoid type. Ectomycorrhizae were more common in communities of low diversity; VAM occurred more frequently in communities of high plant species diversity.

Evolutionary trends in root-microbe symbioses

1996 ◽  
Vol 351 (1345) ◽  
pp. 1367-1375 ◽  
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Arbuscular Mycorrhizas ◽  
Plant Roots ◽  
Mycorrhizal Symbiosis ◽  
Evolutionary Trends ◽  
Symbiotic Associations ◽  
Phylogenetic Pattern ◽  
Mycorrhizal Associations ◽  
Wide Range ◽  
Ectomycorrhizal Association

Some of the various symbiotic associations that occur between plant roots and microbes are found on a very wide range of plants, others on very few. By far the most widespread association is the arbuscular mycorrhizal symbiosis, which appears to be an ancestral characteristic; other mycorrhizas and all bacterial nodule symbioses have much more restricted distributions. It has recently been shown that the ability to form nitrogen-fixing symbioses is a trait that occurs in only one clade of the angiosperms. Here we analyse the phylogenetic pattern of mycorrhizal associations, and show that the ectomycorrhizal association has almost certainly arisen more than once, although other types are more concentrated phylogenetically. A detailed com parative analysis of these symbioses awaits a more secure dataset, but it has been possible to undertake such an analysis for arbuscular mycorrhizas in the British flora, which has revealed that the non-mycorrhizal state is a derived one representing habitat and other forms of specialization.

A survey of mycorrhizal plants on Truelove Lowland, Devon Island, N.W.T., Canada

1990 ◽  
Vol 68 (9) ◽  
pp. 1848-1856 ◽  
Author(s):  
C. Bledsoe ◽  
P. Klein ◽  
L. C. Bliss
Keyword(s):  
Plant Species ◽  
High Arctic ◽  
Cenococcum Geophilum ◽  
Soil Extracts ◽  
Vaccinium Uliginosum ◽  
Devon Island ◽  
Ericoid Mycorrhizae ◽  
Arctic Regions ◽  
Arctic Soils ◽  
Mycorrhizal Associations

Although mycorrhizal associations are commonly found on roots of most plant species, little is known about the presence or absence of mycorrhizae in arctic regions. In the Canadian High Arctic, roots of 55 herbaceous and woody plant species were examined for mycorrhizae during the summers of 1987 and 1988 on Devon Island, N.W.T. Ectomycorrhizal associations were found on roots of Salix arctica, Dryas integrifolia, and Potentilla hyparctica; ericoid mycorrhizae formed on Cassiope tetragona and Vaccinium uliginosum. Ectomycorrhizal roots were often covered with black hyphae resembling the fungus Cenococcum geophilum; sclerotia characteristic of this fungus were found in soil extracts. Plants expected to have endomycorrhizal associations were apparently nonmycorrhizal in the traditional sense, since no arbuscules, vesicles, or pelotons were found on any roots during two field seasons. Although extensive fungal hyphae were often present on and within roots, these hyphae could not be conclusively identified as endomycorrhizal. Some dark, septate hyphae were present; their function, although unknown, may be beneficial to the host. In a series of greenhouse bioassays using arctic soils, no endomycorrhizal associations developed on test plants. Spores of vesicular–arbuscular fungi were not found in soil extracts. Thus in this survey, only ectomycorrhizal associations were observed, suggesting that the cold, dry winter and cold, wet summer climates in this area of the High Arctic severely limit formation of endomycorrhizae. Key words: roots, fungi, ectomycorrhizae, endomycorrhizae, arctic.

Seasonal and temperature effects on mycorrhizal activity and dependence of cool- and warm-season tallgrass prairie grasses

1992 ◽  
Vol 70 (8) ◽  
pp. 1596-1602 ◽  
Author(s):  
S. P. Bentivenga ◽  
B. A. D. Hetrick
Keyword(s):  
Tallgrass Prairie ◽  
Mycorrhizal Fungi ◽  
Warm Season ◽  
Growing Season ◽  
Cool Temperature ◽  
Cool Season ◽  
Fungal Activity ◽  
Prairie Grasses ◽  
Vesicular Arbuscular ◽  
Warm Season Grasses

Previous research on North American tallgrass prairie grasses has shown that warm-season grasses rely heavily on vesicular–arbuscular mycorrhizal symbiosis, while cool-season grasses are less dependent on the symbiosis (i.e., receive less benefit). This led to the hypothesis that cool-season grasses are less dependent on the symbiosis, because the growth of these plants occurs when mycorrhizal fungi are inactive. Field studies were performed to assess the effect of phenology of cool- and warm-season grasses on mycorrhizal fungal activity and fungal species composition. Mycorrhizal fungal activity in field samples was assessed using the vital stain nitro blue tetrazolium in addition to traditional staining techniques. Mycorrhizal activity was greater in cool-season grasses than in warm-season grasses early (April and May) and late (December) in the growing season, while mycorrhizal activity in roots of the warm-season grasses was greater (compared with cool-season grasses) in midseason (July and August). Active mycorrhizal colonization was relatively high in both groups of grasses late in the growing season, suggesting that mycorrhizal fungi may proliferate internally or may be parasitic at this time. Total Glomales sporulation was generally greater in the rhizosphere of cool-season grasses in June and in the rhizosphere of the warm-season grasses in October. A growth chamber experiment was conducted to examine the effect of temperature on mycorrhizal dependence of cool- and warm-season grasses. For both groups of grasses, mycorrhizal dependence was greatest at the temperature that favored growth of the host. The results suggest that mycorrhizal fungi are active in roots when cool-season grasses are growing and that cool-season grasses may receive benefit from the symbiosis under relatively cool temperature regimes. Key words: cool-season grasses, tallgrass prairie, vesicular–arbuscular mycorrhizae, warm-season grasses.

Applications of the herbicide sethoxydim increase wheat yield in the absence of weeds

1996 ◽  
Vol 36 (5) ◽  
pp. 555
Author(s):  
ID Black ◽  
CB Dyson ◽  
AR Fischle
Keyword(s):  
Leaf Growth ◽  
Wheat Yield ◽  
South Australia ◽  
Growing Season ◽  
Degree Days ◽  
Experimental Site ◽  
Yield Increase ◽  
Growing Seasons ◽  
Positive Linear Correlation ◽  
Area North

In 11 experiments over 6 seasons the herbicide sethoxydim was applied to Machete, Spear and Blade wheat cultivars in the absence or near absence of weeds (10 sites) or where the weeds were controlled by selective herbicides (1 site), in the cropping area north of Adelaide, South Australia. The rates applied included 9-47 g a.i./ha at the 2-3 leaf growth stage and 9-74 g a.i./ha at early tillering. Except for the very long growing season of 1992, there was a highly significant positive linear correlation between the number of degree days in the growing season at each experimental site and relative mean yield increase of these sethoxydim treatments. Yield increases ranged from nil in growing seasons of about 1000 degree days to 32% in a growing season of 1480 degree days, with a median of 8% over the experiments.

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.

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