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1.
The effect of the fungicide, chlorothalonil, on vesicular-arbuscular mycorrhizal (VAM) symbiosis was studied in a greenhouse
using Leucaena leucocephala as test plant. Chlorothalonil was applied to soil at 0, 50, 100 and 200 μg g−1. The initial soil solution P levels were 0.003 μg mL−1 (sub-optimal) and 0.026 μg mL−1 (optimal). After 4 weeks, the sub-optimal P level was raised to 0.6 μg mL−1 (high). The soil was either uninoculated or inoculated with the VAM fungus, Glomus aggregatum. The fungicide reduced mycorrhizal colonization of roots, development of mycorrhizal effectiveness, shoot P concentration
and uptake and dry matter yields at all concentrations tested, although the highest inhibitory effect was noted as the concentration
of the fungicide was increased from 50 to 100 μg g−1. Phosphorus applied after four weeks tended to partially offset the deleterious effects of chlorothalonil in plants grown
in the inoculated and uninoculated soil which suggests that the fungicide was interfering with plant P uptake. The results
suggest that the use of chlorothalonil should be restricted to levels below 50 μg g−1 if the benefits of mycorrhizal symbiosis are to be expected.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464.
Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464. 相似文献
2.
Development of two endomycorrhizal symbioses on soybean and comparison with phosphorus fertilization
Summary Soybean (Glycine max L. Merr. cv. Amsoy 71) plants were grown in a greenhouse in a soil very low in plant-available P, and plants were harvested
5 times over a 21-week growth period. Soybeans were inoculated with one of two species of VAM fungi or received daily one
of three nutrient solutions of different P concentrations (0.0, 0.2, or 1.0mMP). Until week 9, the dry weights, leaf areas and developmental stage of soybeans inoculated withG. fasciculatum orG. mosseae were similar to the 1.0 or 0.2mMP-treated plants, respectively. Phosphorus concentrations were significantly lower in VAM plants at weeks 6 and 9 as compared
to non-VAM soybeans given 1.0mMP, suggesting P input in VAM plants was immediately used for new growth. Total P input for VAM plants was linear over 21 weeks,
and the average rate of P uptake for these plants was 0.19mg P d−1. Estimated specific P uptake rates (SPUR) for the mycorrhizae (VAM roots) were twice that of the control (0.0mMP) roots. The calculated SPURs forG. fasciculatum andG. mosseae hyphae were 95 and 120μg P g−1 VAM d−1 respectively, a 4 to 5 fold increase over non-inoculated roots, indicating more attention must be paid to P assimilation
by VAM fungi in P-fixing substrates.
Contribution from the Western Regional Research Center, USDA-ARS (CRIS No. 5325-20580-003). 相似文献
3.
The effect of pretransplant inoculation with VA mycorrhizal fungi on the subsequent growth of leeks in the field 总被引:1,自引:1,他引:0
Summary Leek plants were preinoculated with a mixed inoculum ofGlomus caledonium, Glomus fasciculatum andGlomus sp., and transplanted to Dazomet disinfected and untreated field plots of moderate P deficiency. Successive harvests were
made until 99 days after transplanting. Preinoculated leeks attained marketable weights 25 days earlier than uninoculated
leeks from untreated soil and their final dry matter yields were 5.7 and 1.5 times as high as those of uninoculated leeks
from disinfected and untreated soil, respectively. Phosphorus concentration in preinoculated leeks remained highest for at
least 22 and 75 days after transplanting in untreated and disinfected soil, respectively. Preinoculation had a similar, although
smaller, influence on Cu and Zn concentrations. Infection levels produced by introduced and indigenous VA endophytes in leeks
reached plateaus of 90% and 40%, respectively, 47 days after transplanting. It is concluded that VAM is essential to leeks
grown in moderately P deficient soils, and the potential for inoculating seedlings in commercial leek production is discussed. 相似文献
4.
The aim of this field study was to examine how the development of arbuscular mycorrhizal fungi (AMF) on coal mine spoil banks
is affected by the presence of plants with different mycorrhizal status. A 3-year trial was conducted on the freshly created
spoil bank Vršany, North-Bohemian coal basin, the Czech Republic. Three plant species – non-mycotrophic annual Atriplex sagittata, highly mycotrophic annual Tripleurospermum inodorum (both dominants of early stages of succession) and facultatively mycotrophic Arrhenatherum elatius (a perennial grass species of the later stage of succession) – were planted on 1 m2 plots over 3 years in different sequences that simulated the progress of succession on spoil banks. The development of AMF
populations was monitored by evaluation of mycorrhizal colonization of plant roots and by measurement of the mycorrhizal inoculation
potential (MIP) of soil. These two parameters were compared between plots inoculated with the mixture of three AMF isolates
– Glomus mosseae BEG95, G. claroideum BEG96 and G. intraradices BEG140 – (“inoculated plots”) and plots exposed only to natural dispersal of AMF propagules (“uninoculated plots”). Highly
colonized roots of plants together with a high MIP of soil in uninoculated plots were already found at the end of the first
season, indicating rapid natural dispersal of AMF propagules. Root colonization of facultatively mycotrophic and non-mycotrophic
plants in later years was affected by the mycorrhizal status of the previous plant species. The MIP of soil continuously increased
throughout the experiment; in uninoculated plots, the MIP was temporarily decreased if plant species of higher mycotrophy
were replaced by species of lower mycotrophy. The results lead to the conclusion that AMF colonize freshly formed sites very
quickly and reproduce or accumulate in the soil, which leads to increasing MIP values. However, this infective potential can
be decreased if non-mycotrophic plants predominate on the site. 相似文献
5.
The individual and combined effects of two arbuscular mycorrhizal fungi (AMF), Meloidogyne arenaria, and phosphorus (P) fertilization, (0, 25, 75, and 125 μg/g soil) on peanut plant growth and pod yield were determined in
greenhouse studies. Best growth and yield usually occurred at 75 or 125 μg P regardless of inoculation treatment. Peanut growth
and yield were generally stimulated by AMF development, and growth alone was suppressed by M. arenaria at 0 and 25 μg P. In challenge inoculations, VAM increased peanut plant tolerance to the nematode and offset the growth reductions
caused by M. arenaria at the two lower P levels. However, VAM and added P increased galling and M. arenaria egg production/g root, thereby increasing peanut susceptibility to nematode attack. M. arenaria had only a minimal effect on root colonization by AMF and sporulation by the fungi.
Accepted: 9 June 1995 相似文献
6.
The growth response of Hevea brasiliensis to vesicular-arbuscular mycorrhizal (VAM) fungi inoculation was assessed in two field nursery sites containing indigenous
mycorrhizal fungi (IMF). Seedling rootstocks were inoculated with mixed VAM-fungal species in a factorial combination with
phosphorus (P) fertilizer application, and planted in randomised blocks on sandy (site 1) and clayey (site 2) soils. Plants
were harvested after 26 weeks for measurements of shoot dry weight (DW), stem diameter, height, mycorrhizal root colonization
and leaf nutrient contents. At site 1, VAM increased shoot DW, stem diameter and plant height only in treatments without P
applied. Increases in shoot DW due to VAM were 70% greater than the uninoculated controls although this was reduced to 5%
when P was applied. At site 2, VAM inoculation also increased shoot DW and stem diameter but the magnitude of the increases
was smaller. Shoot DW response due to VAM was only 29%. At this second site, applying phosphate to uninoculated plants did
not increase shoot yields further. Leaf concentrations of all nutrients were unaffected by VAM at both sites, except for copper
(Cu) which was increased by VAM in treatments where P was not applied. However, leaf contents of P, potassium (K), magnesium
(Mg) and Cu were increased by VAM at site 1, and of leaf nitrogen (N) and K at site 2. These experiments demonstrate that
VAM-fungi could be introduced into field nursery sites to improve growth and P uptake by H. brasiliensis. The relevance of VAM-fungi to H. brasiliensis seedling rootstock development and the influence of IMF in determining field responses is discussed. 相似文献
7.
M. Vosátka 《Folia microbiologica》1994,39(4):304-306
An influence of dual inoculation with the rhizosphere bacteriumAgrobacterium radiobacter, and the VAM fungi,Glomus mosseae andGlomus sp., on maize growth and mycorrhizal infection was observed. Separate inoculations of bacteria or fungi showed significant
positive effects on the shoot biomass production of pot-cultured plants only at the last of three consecutive harvests. Plant
biomass production was enhanced substantially after a dual inoculation with bacteria and fungi. Synergistic interaction of
fungal and bacterial inoculation and growth stimulation was evident at all three harvests compared to uninoculated plants
and also compared to plants inoculated with fungi or bacteria only. The dual inoculation increased the shoot biomass of plants
by approximately 30% as compared with control. No significant differences were found in mycorrhizal infection between plants
uninoculated and inoculated with bacteria.Agrobacterium radiobacter seems to be compatible with mycorrhizal symbiosis and can act a synergistic partner of some VAM fungi. 相似文献
8.
I. Jakobsen 《Plant and Soil》1987,98(3):407-415
Summary A field experiment was carried out to study the influence of vesicular-arbuscular mycorrhiza (VAM) on nutrient uptake and
growth of pea at two levels of P fertilizer. Pea was grown in dazomet-fumigated and non-fumigated soil, either with or without
addition of inoculum of VAM fungi. Dazomet efficiently eliminated infection by indigenous VAM fungi, whereas roots from untreated
soil were extensively infected. Inoculation with VAM fungi increased P uptake by peas in fumigated plots, but had no significant
effect on dry matter production in either soil treatment. However, VAM developed less in inoculated fumigated than in untreated
plots. Seeds of uninfected plants in fumigated plots contained only 56 and 81%, respectively, of the P and dry matter content
of seeds of infected plants in untreated plots. The addition of 60 kg P ha−1 also increased seed yields but to a smaller degree than VAM. The seed yield as a proportion of total shoot yield (harvest
index) was higher in VAM infected than in uninfected peas but was unaffected by P fertilizer. The possible reasons for this
are discussed. 相似文献
9.
Two field experiments were conducted using three dominant perennial species of the Chihuahuan Desert: Hilaria mutica (a tussock grass), Larrea tridentata (a microphyllous shrub) and Opuntia rastrera (a flat-stemmed succulent cactus). Two hypotheses concerning competition in arid plant communities were tested. (1) Marked
resource partitioning with no interspecific competition could be expected since the three species belong to different life-forms,
and that plant growth in deserts is basically limited by harsh environmental conditions. (2) Alternatively, resource scarcity
(particularly water) will result in strong plant competition. In a 1-year removal experiment, water status and plant growth
of the three species were monitored in twelve 10 m × 10 m plots randomized in three blocks and assigned to the following treatments:
(a) removal of all species, except H. mutica; (b) removal of all species, except L. tridentata; (c) removal of all species, except O. rastrera, and (d) control without any manipulation. In a watering experiment, under two neighbourhood conditions (growing isolated
or in associations of plants of the three species in plots of 20 m2), the water status of the three species and the growth of H.mutica and L.tridentata were studied for 32 days after an irrigation equivalent to 30 mm of rain, similar to a strong storm event at the site. In
the removal experiment, where plants were free to capture water, no evidence of competition was observed. However, during
the watering experiment, in which water was forced into the soil, competitive effects were observed. Associated individuals
of L. tridentata had lower xylem water potentials and osmotic potentials (OPs) and produced shorter twigs and less leaves and nodes. Although
less pronounced, neighbours also had a negative effect on the OP in O. rastrera. According to these results, the intensity of the interspecific competition for water seems to depend on the level of resource
availability in the soil. Thus, the validity of the two hypotheses tested in this study also depends on the level of resources.
Competition could be absent or very low in years of low precipitation, as in the year of this study (173 mm against a 25-year
average of 264 mm). However, when soil water availability is high, e.g. following heavy rain, the negative interactions between
species could be more intense.
Received: 3 October 1997 / Accepted: 23 March 1998 相似文献
10.
Regeneration of garlic callus as affected by clonal variation, plant growth regulators and culture conditions over time 总被引:3,自引:0,他引:3
A long-term regeneration system for garlic (Allium sativum L.) clones of diverse origin was developed. Callus was initiated on a modified Gamborg's B-5 medium supplemented with 4.5 μM 2,4-D and maintained on the same basal medium with 4.7 μM picloram+0.49 μM 2iP. Regeneration potential of callus after 5, 12 and 16 months on maintenance medium was measured using several plant growth
regulator treatments. The 1.4 μM picloram+13.3 μM BA treatment stimulated the highest rate of shoot production. Regeneration rate decreased as callus age increased, but healthy
plantlets from callus cultures up to 16-months-old were produced for all clones. Regeneration of long-term garlic callus cultures
could be useful for clonal propagation and transformation.
Received: 24 September 1998 / Revision received: 27 January 1999 / Accepted: 26 February 1999 相似文献
11.
Growth and nutrient status of citrus plants as influenced by mycorrhiza and phosphorus application 总被引:1,自引:0,他引:1
To test the hypothesis that high levels of soluble phosphate applied in combination with VAM fungi, to citrus plants, can
cause growth depression even in the absence of other limiting factors, and also to test if rock phosphate, under these conditions,
may be a satisfactory P source, a greenhouse experiment was conducted using sterilized soil with four levels of phosphate
(0, 50, 100 and 200 ppm P) supplied either as soluble P or as rock phosphate. Citrus seedlings were either inoculated with
the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus etunicatum or left uninoculated. Six months after the start of the experiment, the plants were harvested and shoot dry weight, P and
K uptake, root colonization and the number of spores in 50 cm3 of soil were determined. Significant increases were found in dry matter yields and in P and K contents, due to VAM fungus
inoculation, at the zero and 50 ppm soluble P levels and at all rock phosphate levels. At 100 ppm soluble P, the development
of VAM plants was equilvalent to that of non-VAM plants, and at 200 ppm, growth was significantly less than that of non-VAM
plants. Root colonization and sporulation were reduced at higher P levels. The absolute growth depression of VAM plants at
the higher P level was likely due to P toxicity. In addition, high leaf P and K concentrations may have interfered with carbohydrate
distribution and utilization in these symbioses. Rock phosphate may be used with VAM citrus to substitute for medium amounts
of soluble phosphate. 相似文献
12.
The availability of most edible ectomycorrhizal mushrooms depends on their natural fructification. Sporocarp formation of
these fungi is linked to habitat characteristics and climate conditions, but these data alone do not explain all the trends
of fungal fruiting and dynamics. It could be hypothesized that the amount of soil mycelia could also be related to the production
of carpophores. Soil samples (five cylinders of 250 cm3 per plot) were taken monthly, from September to November, in five fenced permanent plots (5 × 5 m) in Pinar Grande (Soria,
Spain), a Pinus sylvestris stand situated in the north of the Sistema Ibérico mountain range. Plots were chosen to establish a gradient of Boletus edulis productivity from 0 to 38.5 kg/ha year, according to the mean fresh weight of sporocarps collected during the last 10 years.
B. edulis ectomycorrhizal root tips were identified in each soil sample according to its morphology and counted. DNA extractions were
performed with the PowerSoilTM DNA Isolation Kit and quantification of extraradical soil mycelium by real-time polymerase chain reaction using specific
primers and a TaqMan? probe. The concentration of soil mycelium of B. edulis (mg mycelium/g soil) did not differ significantly between plots (p = 0.1397), and sampling time (p = 0.7643) within the fructification period. The number of mycorrhizal short roots per soil volume showed significant differences
between the plots (p = 0.0050) and the three sampling times (p < 0.0001). No significant correlation between the number of mycorrhizas and the productivity of the plot (kg of B. edulis/ha year) was detected (p = 0.615). A statistically significant positive correlation (p = 0.0481) was detected between the concentration of mycelia of B. edulis in the soil samples and the presence of short roots mycorrhizal with B. edulis in these samples. The productivity of the plots, in terms of sporocarps produced during the last 10 years, was not correlated
either with the concentration of soil mycelium or with the presence or abundance of ectomycorrhizas. 相似文献
13.
The effects of Pratylenchus vulnus and the endomycorrhizal fungus Glomus mosseae on growth of Myrobalan 605, Marianna 2624 and San Julian 655-2 plum rootstocks were measured under shadehouse conditions in the field for two growing seasons (1990–91). Shoot dry weights were higher in the majority of the vesicular-arbuscular mycorrhizal (VAM) alone inoculated plants after both growing seasons. Root weights of mycorrhizal Myrobalan and Marianna were higher than root weights of the same rootstocks lacking mycorrhizae, inoculated with P. vulnus, and VAM in combination with the nematode. Mycorrhizal Marianna inoculated with the nematode showed a considerably higher final nematode population in relation to non-inoculated VAM treatments. No correlation was found in the number of nematodes per gram of root between mycorrhizal and non-mycorrhizal treatments. P. vulnus adversely affected the mycorrhizal colonization in Marianna, but not in Myrobalan and San Julian. Marianna appears to be more mycorrhizal dependent than the two other rootstocks. 相似文献
14.
The response ofCicer arietinum to inoculation withGlomus versiforme under field conditions was investigated in a phosphorus deficient sandy loam soil. Inoculation with the mycorrhizal fungusGlomus versiforme increased the rate of VAM development in chickpea. The weight of nodules and the number of nodules per plant were higher
in inoculated than in uninoculated plants. The phosphorus content of the shoots and its total uptake, were increased by either
the application of single super-phosphate, or by inoculation withG. versiforme. Inoculation increased shoot dry weights and grain yields by 12% and 25% respectively, as compared with the 33% and 60% increases
respectively produced by P-treated plants. 相似文献
15.
Triacontanol, a long-chain primary alcohol was found to be an effective growth regulator in the micropropagation of balm,
Melissa officinalis. In both the multiplication and the rooting phase, concentrations of 2, 5, 10 and 20 μg triacontanol per liter were applied.
After 4 weeks of culture, the fresh weight of shoots was measured in the multiplication phase and root formation, photosynthetic
activity, chlorophyll content and the fresh and dry weights of shoots were analyzed in the root induction phase. In the multiplication
phase, 5 μg/l triacontanol was found to be the optimal concentration, while in the rooting phase 2 μg/l was the most effective.
Triacontanol increased the number and length of roots, and it enhanced shoot growth, fresh weight, and the chlorophyll content,
but it had no effect on the dry weight and the photosynthetic activity of the plants. Results of our work demonstrate that
triacontanol can be applied as an effective growth regulator in the tissue culture of balm.
Received: 3 December 1997 / Revised: 24 February 1998 / Accepted: 26 February 1999 相似文献
16.
Maple sap, an abundant natural product especially in Canada, is rich in sucrose and thus may represent an ideal renewable
feedstock for the production of a wide variety of value-added products. In the present study, maple sap or sucrose was employed
as a carbon source to Alcaligenes latus for the production of poly-β-hydroxybutyrate (PHB). In shake flasks, the biomass obtained from both the sap and sucrose were
4.4 ± 0.5 and 2.9 ± 0.3 g/L, and the PHB contents were 77.6 ± 1.5 and 74.1 ± 2.0%, respectively. Subsequent batch fermentation
(10 L sap) resulted in the formation of 4.2 ± 0.3 g/L biomass and a PHB content of 77.0 ± 2.6%. The number average molecular
weights of the PHB produced by A. latus from maple sap and pure sucrose media were 300 ± 66 × 103 and 313 ± 104 × 103 g/mol, respectively. Near-infrared, 1H magnetic resonance imaging (MRI), and 13C-MRI spectra of the microbially produced PHB completely matched those obtained with a reference material of poly[(R)-3-hydroxybutyric
acid]. The polymer was found to be optically active with [α]25
D equaled to −7.87 in chloroform. The melting point (177.0°C) and enthalpy of fusion (77.2 J/g) of the polymer were also in
line with those reported, i.e., 177°C and 81 J/g, respectively. 相似文献
17.
Eucalyptus is an important tree species used for afforestation of large tracts of marginal and wastelands. Eucalyptus-arbuscular mycorrhizal fungal (AMF) interactions in seedling establishment and growth promotion have been inadequately dealt
with. Efforts were made to assess the role of AMF-pseudomonad (PRS9, plant growth promotory fluorescent Pseudomonas) interactions in growth promotion and nursery establishment of E. hybrid. Seedlings were subjected to six different treatments: (i) uninoculated control, (ii) 400 AM spores, (iii) 800 AMF spores,
(iv) PRS9 (v) 400 AMF spores + PRS9, (vi) 800 AMF spores + PRS9, with the different P regimes of 10, 20 and 30 ppm. Root length,
shoot length, root and shoot fresh and dry weights were maximal at 400 AMF spores and 20 ppm soil P. Shoot P content was maximal
at 800 AMF spores followed by 400 AMF spores and 400 AMF spores + PRS9. In general, plant growth was greater at 20 ppm P.
Root P content increased significantly with 400 AMF spores followed by 800 at 20 ppm P. Independent of soil P levels, the
quality index of mycorrhizal treatments without PRS9 was significantly higher than the treatments including PRS9 or PRS9 alone.
Mycorrhizal inoculation efficiency was superior at 10 ppm P irrespective of the treatment. AM alone (400 spores) significantly
improved the inoculation efficiency. PRS9 in association with AM fungi inhibited growth promotion and nutrient uptake
Accepted: 8 September 1999 相似文献
18.
Fuxa JR 《Microbial ecology》2008,55(3):530-539
The purpose of the research was to determine threshold concentrations of nucleopolyhedrovirus (NPV) in soil for abiotic transport
to cotton plants in the field and under conducive and nonconducive conditions in the greenhouse. Under the assumption that
2% mortality would suffice to initiate foci of infection in Heliothis virescens larvae on the plants, thresholds ranged from 25 to 2,311 viral occlusion bodies (OB)/g soil in the greenhouse. Thresholds
generally were smaller for rain on sandy soil and wind on clay soil than for wind on sand or rain on clay. Thresholds generally
increased with height of the plant above the soil surface. In field plots, percentage mortality in bioassays of cotton plants
was greatest on leaves versus other tissues, and mortality increased with soil dosage and decreased with plant height and
over time. Season-long soil-NPV-transport thresholds for 2% plant-bioassay mortality of larvae ranged from 1 OB/g to 7.4 × 108 OB/g soil based on the amounts of NPV applied to the soil at planting time, and they ranged from 8 OB/g to 1.2 × 105 OB/g soil based on bioassays of soil samples collected concurrently with plant samples throughout the growing season. These
results should contribute to NPV epizootiology, biological control, and risk assessment through better understanding of viral
soil-to-plant transport. 相似文献
19.
Ralph E. J. Boerner 《American journal of botany》1990,77(4):483-489
Prior field studies have shown that populations of forest herbs on relatively nutrient poor soils have higher vesicular-arbuscular mycorrhizal (VAM) infection intensity than plants on rich soils. However, the growth responses and ability to take up P against the soil nutrient gradient are often not linearly related to infection intensity. To determine if intraspecific differences among populations of the common VAM fungus Glomus occultum could differentially affect growth and nutrient uptake, Geranium robertianum seedlings were inoculated with Glomus occultum isolated from four forest types along a gradient of soil fertility, and grown in a greenhouse at P levels typical of the extremes of that gradient. Plants given inoculum from relatively infertile forest sites generally produced greater root, shoot, and total mass than plants given inoculum from fertile sites or uninoculated plants, especially at the low P supply rate. Total P uptake and both P and N uptake efficiency were also highest in plants given inocula from low fertility sites. These results indicate that local adaptation and intraspecific variations in the ability of VAM fungi to induce growth and nutrient uptake effects on host plants may be as important as interspecific differences among VAM fungus species. 相似文献
20.
In field experiments in 1981 and 1982, uninoculated seed tubers (cv. Désirée) and those inoculated with Erwinia carotovora subsp. atroseptica at the rose (apical) or heel (stolon attachment) ends were planted at normal (35 cm) or double spacing; in additional plots, inoculated and uninoculated tubers were planted alternately. Inoculation, especially at the rose end, decreased plant height and sometimes resulted in blackleg symptoms. Individual plant yields were recorded at the end of the season. In plots of uniform seed type at normal spacing, inoculation decreased total yield compared with uninoculated by 12–13% (heel-end inoculation) or 26–40% (rose-end inoculation). At double spacing, yields increased compared with normal spacing by 44–58% (uninoculated or heel-end inoculation) or 30–39% (rose-end inoculation). When rose-end-inoculated and uninoculated seed tubers were planted alternately, inoculated plants yielded less and uninoculated plants more than in plots planted throughout with the same seed treatment. The abilities of inoculated and uninoculated plants to compensate for weak or missing neighbours were combined using equations to predict the yields of crops with different proportions of diseased or missing plants. 相似文献