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1.
S. Kannaiyan 《Plant and Soil》1988,108(2):299-302
The effect of fungicidesviz. Benomyl, Carbendazim, Chloroneb, Kitazin, Edifenphos, Thiabendazole and Wettable ceresan on the production of enzymes byR. solani was studied. The fungicides tested were inhibitory to the production and activity of amylase, invertase and cellulase. The fungicides inhibited the growth of the fungus to a considerable extent.  相似文献   

2.
Eighteen fungal species were isolated from rhizospheric soil and rhizoplane samples of three plant crops in southern Iraq. The fungal isolates were examined for the activities of four enzymes (amylase, cellulase, phenoloxidase, and protease), as well as their growth, against crude garlic extract added to the culture agar medium. A high reduction or inhibition of enzymatic activities was observed for the fungi treated with garlic extract compared with untreated fungal cultures. However, most of the species showed inhibition of enzymes due to the effect of garlic extract. The growth of the fungal species was also remarkably reduced by the garlic extract.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

3.
《农业工程》2019,39(6):456-460
Helminthosporium oryzae, a fungal pathogen causing Brown Spot of Rice is one of the disastrous biotic factors responsible for 16–43% yield in rice. To control in vitro fungal growth of this pathogen, four fungicides viz. Mencozeb, Thiophanate Methyl, Iprovalicarb + Propineb and Propineb were used with four different concentrations: 50, 100, 150 and 200 ppm. Plant extracts of five species as Azadirachta indica, Calotropisprocera, Allium sativum, Datura stramonium and Zingiber officinale were also tested with three doses (5, 10 and 15 ml). While, 24 isolates of Bacterial isolates were investigated for their antagonistic effect. The in vitro results of the four fungicides contributed that Mancozeb and Thiophanate Methyl inhibited the colony growth at the higher doses (150 and 200 ppm) with no linear colony growth. However, Propineb was found moderately effective at (5.00 mm) and Iprovalicarb + Propineb was less effective (7.25 mm). Similarly, the in-vitro efficacy of the five plant extracts against H. oryzae at different doses revealed that Zingiber officinale and Allium sativum were more effective at high doses (00.00 mm, 2. mm). Also, Datura stramonium (4.62 mm) Azadirachta indica (18.00 mm) and Calotropisprocera (12.00 mm) performed better as compared to the control (40.00 mm). The results revealed that out of 24 isolates, 4 isolates of bacteria Agrobacterium spp, Xanthomonas, Erwinia, Streptomyces has inhibited the linear colony growth of H. oryzae up to 1-2 mm. This study can be useful for controlling the fungal disease as the two fungicides Mancozeb and Thiophanate Methyl were more effective and the Zingiber officinale and Allium sativum plant extracts were highly effective against the brown spot of rice. Biocontrol also reduced leaner colony Helminthosporium oryzae.  相似文献   

4.
Glucophilic and cellulose-decomposing fungi were significantly reduced in soil samples treated with 0.019-0.152 mg a.i./kg soil of the herbicides Herbizid and Touchdown. The decrease was regularly correlated with the doses of the two herbicides and persisted till the end of the experiment (12 weeks). The isolated fungi were found to be able to produce hydrolytic extracellular enzymes in solid media but with variable capabilities. The ability to produce enzymes was adversily affected by the incorporation of herbicides in culture media. Lower doses of herbicides were occasionally promotive to enzyme production and mycelial growth of some fungi. Incorporation of 50 ppm of Herbizid and Touchdown significantly activated amylase production and mycelial dry weight in cultures of Fusarium oxysporum, Mucor hiemalis and Penicillium chrysogenum. There was a significant increase in C1-cellulase produced by F. oxysporum and P. aurantiogriseum when cultures were treated with 50, 100 and 200 ppm of Herbizid which induced also more Cx-cellulase production by P. chrysogenum. Lipase and protease production was always lower in treated than in control fungal cultures.  相似文献   

5.
Ergosterol content was determined in 20 white-rot fungi isolates and the values ranged from 2380 to 13 060 μg g−1 fungal biomass. Significant changes of ergosterol content according the physiological stage for Bjerkandera adusta 4312 and Coriolopsis gallica 8260 were found, showing the highest values during the stationary phase. However, in the case of Phanerochaete chrysosporium 3642, no changes were detected during growth. The effect of pollutants, such as heavy metals and fungicides, on the ergosterol content of C. gallica was determined. Heavy metals (Cu 80 ppm, Zn 50 ppm or Cd 10 ppm) and fungicides (thiram 3 ppm or pentachlorophenol 1.5 ppm) at concentrations that reduce the metabolic activity between 18% and 53% (pollutant-stressed cultures) did not affect the ergosterol content. Only the fungicide zineb (25 ppm) reduced significantly the ergosterol content in biomass basis. In soil experiments with Cu (80 ppm) or thiram (10 ppm) after 15 and 30 days of incubation, the ergosterol content in soil was linearly correlated to the fungal biomass C in both polluted and control soil cultures. The ergosterol content was independent of the presence or the absence of pollutants. Thus, these results indicate that ergosterol can be a useful indicator for fungal biomass in polluted soils, and can be applied for monitoring bioremediation processes.  相似文献   

6.
This study reports the effects of long-term elevated atmospheric CO2 on root production and microbial activity, biomass, and diversity in a chaparral ecosystem in southern California. The free air CO2 enrichment (FACE) ring was located in a stand dominated by the woody shrub Adenostoma fasciculatum. Between 1995 and 2003, the FACE ring maintained an average daytime atmospheric CO2 concentration of 550 ppm. During the last two years of operation, observations were made on soil cores collected from the FACE ring and adjacent areas of chaparral with ambient CO2 levels. Root biomass roughly doubled in the FACE plot. Microbial biomass and activity were related to soil organic matter (OM) content, and so analysis of covariance was used to detect CO2 effects while controlling for variation across the landscape. Extracellular enzymatic activity (cellulase and amylase) and microbial biomass C (chloroform fumigation-extraction) increased more rapidly with OM in the FACE plot than in controls, but glucose substrate-induced respiration (SIR) rates did not. The metabolic quotient (field respiration over potential respiration) was significantly higher in FACE samples, possibly indicating that microbial respiration was less C limited under high CO2. The treatments also differed in the ratio of SIR to microbial biomass C, indicating a metabolic difference between the microbial communities. Bacterial diversity, described by 16S rRNA clone libraries, was unaffected by the CO2 treatment, but fungal biomass was stimulated. Furthermore, fungal biomass was correlated with cellulase and amylase activities, indicating that fungi were responsible for the stimulation of enzymatic activity in the FACE treatment.  相似文献   

7.
The effect of a commercial Aspergillus oryzae fermentation extract on the utilization of carbon source and zoospore production by the rumen fungus Neocallimastix frontalis EB 188 was determined. In addition, the composition of a soluble extract prepared from the commercial product was analyzed. This extract was added to N. frontalis EB 188 cultures grown on a variety of substrates and periodically assayed for protein, enzymes, zoospore production, and carbon source utilization. The powdered product contained 93% dry matter, more than 3,000 A. oryzaespores per gram, and did not contain strong buffers or high concentrations of salt. Measurable concentrations of DNA, protein, carbohydrate and several enzymes including cellulase and amylase were also found. Soluble extract increased fungal physiology and treated cultures produced significantly higher levels of supernatant protein and enzymes including amylase, cellulase and beta-glucosidase. The fungal response depended on culture carbon source. However, culture zoospore production was increased regardless of substrate provided. Culture utilization of glucose was more rapid in treated cultures, yet high levels of the extract greatly inhibited glucose utilization.  相似文献   

8.
Kocide 101 (77% cupric hydroxide) and Ridomil plus (15% metalaxyl and 35% copper oxychloride) were used in the treatment of tomato plants in the field. Generally, the two fungicides exhibited an inhibitive effect on the total and individual counts of glucophilic fungi after different periods of treatment except in some cases, the counts were not affected or promoted compared with the control. Fungal genera and species associated with roots and shoots of tomato plants were isolated from untreated plants as control and then compared with those isolated from plants treated with different doses of fungicides. The most common fungal species recovered from soil and different parts of plants were Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Cochliobolus spicifer, Emericella nidulans, E. nidulans var. lata, Fusarium oxysporum, Gibberella fujikuroi, Mycosphaerella tassiana, Nectria haematococca, Penicillium chrysogenum, P. funiculosum, P. oxalicum, Stachybotrys chartarum and Rhizopus stolonifer.  相似文献   

9.
Aspergillus funiculosus was isolated from rotted banana fruits, whereas Alternaria tenuis and Fusarium sp. were isolated from rotted tomato fruits. The isolated fungi tolerated relatively high levels of the fungicide, Dithane, up to 2560 ppm on solid medium, but grew well at 40 ppm when supplemented with liquid medium. They are able to tolerate selenite up to 2% (w/v) sodium selenite. A. funiculosus showed no growth in the presence of mixture of 2.5 ppm selenium and 20 ppm Dithane, whereas Fusarium sp. failed to grow at 2.5 ppm selenium and 10 ppm Dithane, or at 10 ppm of each. Nevertheless, Alternaria tenuis is more tolerant; it showed growth in the presence of relatively high levels of selenium and Dithane; up to 10 ppm selenium and 40 ppm Dithane, however, its growth was inhibited by the presence of a mixture of both. The results suggested new form of highly active fungicides. Selenium as an essential nutrient at such very low concentrations, as well as the application of very low concentrations of the fungicide, would certainly reduce the hazardous effect of such pollutant in the environment.  相似文献   

10.
Among 39 fungal species and one variety belonging to 16 genera isolated from 116 healthy tomato fruits collected from markets in Assiut, Egypt, during 1994,Aspergillus niger was found to be the most prevalent, being isolated from 84.6% of the samples. Of 11 species recovered from 156 diseased tomatoes,Alternaria alternata, Rhizopus stolonifer andA. niger were the most common and isolated from 52.7%, 35.9% and 25.0% of the samples, respectively. Experiments for comparison of the effects of medium containing tomato juice with synthetic medium on the mycelial growth of nine fungal species indicated that, the tomato juice medium was more suitable for growth of all fungal species. The effect of five commercial fungicides and sodium hypochlorite when applied as post-harvest dips after inoculation was studied in laboratory againstA. alternata, A. niger andR. stolonifer. At 10 and 100 µg ml–1, neither of the fungicide caused a noticeable inhibition ofAlternaria rot. At 1000 µg ml–1 benlate, rovral and sumisclex completely preventedAlternaria andAspergillus rot, whereas cuprosan and ridomil were ineffective against rotting caused byA. niger. Rhizopus rot development was inhibited by over 50% with one treatment only (rovral at 1000 µg ml–1). Sodium hypochlorite has good curative properties against fruit rots especially those caused byA. alternata andA. niger.  相似文献   

11.
The effect of 20 essential oil constituents on Aspergillus flavus growth and aflatoxin production was tested at the level of 1000 ppm. Some of the tested oils exhibited inhibitory effects on fungal growth and toxin formation. Five oils, namely geraniol, nerol and citronellol (aliphatic oils), cinnamaldehyde (aromatic aldehyde) and thymol (phenolic ketone), completely suppressed growth and aflatoxin synthesis. Trials for determining the minimum inhibitory concentration (MIC) of these oils revealed that geraniol, nerol and citronellol were effective at 500 ppm, while thymol and cinnamaldehyde were highly effective at doses as low as 250 and 200 ppm, respectively. It was observed that citral, citronellal and eugenol prevented fungal growth and toxin formation for up to 8 d. However, after 15 d of incubation, toxin production was greater than the controls.  相似文献   

12.
Availability of phosphorus and sulfur of insecticide origin by fungi   总被引:8,自引:0,他引:8  
Omar SA 《Biodegradation》1998,9(5):327-336
Thirteen fungal species isolated from soil treated with pesticides were tested for their ability to mineralize and degrade three organophosphate insecticides currently used in Egypt (Cyolan®, Malathion® and Dursban®) in liquid media free from phosporus (P) and sulfur (S). All fungal species grew successfully on the culture media treated with the three used doses of insecticides (10, 50 and 100 ppm active ingredient) but the growth rate varied with the species, the insecticide and the doses. At 10 ppm level, insecticide degradation expressed in term of organic P mineralization (calculated as % of applied P) was the highest with all fungi tested. Organic P mineralization from pesticides was decreased by increasing the dose used to 50 and 100 ppm. The highest amount of P mineralized was observed with Cyolan® followed by Malathion® whilst P mineralization from Dursban® proceeded very slowly. Aspergillus terreus showed the greatest potential to mineralize organic P followed by A. tamarii, A. niger, Trichoderma harzianum and Penicillium brevicompactum whilst the remaining fungi only moderately mineralized the organic P component of the insecticides tested. Organic sulfur mineralization by the used fungal species paralleled, to some extent, organic P mineralization. The extracellular protein content of culture filtrates in the presence of various doses of insecticides was also decreased by increasing insecticide concentrations. The extracellular protein was significantly correlated with P and S mineralization (r = 0.89** and 0.64**, respectively) whilst correlation with cell dry mass was not significant (r = 0.03 and 0.003) suggesting a direct relationship between pesticide degradation and microbial protein production. The addition of P or S to the growth media enhanced extracellular protein excretion, and increased organic P and S mineralization by the most potent species tested (A. niger, A. tamarii, A. terreus and T. harzianum). This increment was significant in most cases, especially at the higher application rates. The relationship between extracellular protein excretion and organic P and S mineralization from insecticides was highly significant with the addition of inorganic phosphorus (r = 0.96** and 0.83**, respectively) or sulfur (r = 0.85** and 0.89**, respectively) to the growth media.  相似文献   

13.
Solid media containing carboxymethyl cellulose (CMC) were developed to detect CX cellulose-producing micro-organisms. Hydrolysis of CMC was seen as a clear zone around colonies after flooding plates with 1% aqueous hexadecyltrimethyl-ammonium bromide. Tests with ten bacterial and four fungal species showed that the degree of substitution (DS) of the CMC affects both growth and enzyme production. Most of the organisms produced more CX cellulase on CMC with a DS of 0-9, but CMC with a DS of 0-4 was better for one fungus. A qualitative measure of cellulase production may be obtained by calculating the ratio of zone size to colony diameter. Solid media containing CMC provided a more rapid assay of CX cellulose production than a medium containing native cellulose.  相似文献   

14.
Leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens, produces polysaccharidases that degrade leaf components by generating nutrients believed to be essential for ant nutrition. We evaluated pectinase, amylase, xylanase, and cellulase production by L. gongylophorus in laboratory cultures and found that polysaccharidases are produced during fungal growth on pectin, starch, cellulose, xylan, or glucose but not cellulase, whose production is inhibited during fungal growth on xylan. Pectin was the carbon source that best stimulated the production of enzymes, which showed that pectinase had the highest production activity of all of the carbon sources tested, indicating that the presence of pectin and the production of pectinase are key features for symbiotic nutrition on plant material. During growth on starch and cellulose, polysaccharidase production level was intermediate, although during growth on xylan and glucose, enzyme production was very low. We propose a possible profile of polysaccharide degradation inside the nest, where the fungus is cultured on the foliar substrate.  相似文献   

15.
Lipids created via microbial biosynthesis are a potential raw material to replace plant-based oil for biodiesel production. Oleaginous microbial species currently available are capable of accumulating high amount of lipids in their cell biomass, but rarely can directly utilize lignocellulosic biomass as substrates. Thus this research focused on the screening and selection of new fungal strains that generate both lipids and hydrolytic enzymes. To search for oleaginous fungal strains in the soybean plant, endophytic fungi and fungi close to the plant roots were studied as a microbial source. Among 33 endophytic fungal isolates screened from the soybean plant, 13 have high lipid content (>20 % dry biomass weight); among 38 fungal isolates screened from the soil surrounding the soybean roots, 14 have high lipid content. Also, five fungal isolates with both high lipid content and promising biomass production were selected for further studies on their cell growth, oil accumulation, lipid content and profile, utilization of various carbon sources, and cellulase production. The results indicate that most strains could utilize different types of carbon sources and some strains accumulated >40 % of the lipids based on the dry cell biomass weight. Among these promising strains, some Fusarium strains specifically showed considerable production of cellulase, which offers great potential for biodiesel production by directly utilizing inexpensive lignocellulosic material as feedstock.  相似文献   

16.
The sheath blight of rice pathogen Rhizoctonia solani Kühn AG1-1A has long been known as a major crisis in global rice production. The present study aimed to compare the efficacy of four triazole fungicides at different doses on the growth and development of R. solani Kühn AG1-1A. Obtained results demonstrated inhibitory effects of all four fungicides on mycelial growth, sclerotia formation and biomass production of R. solani Kühn AG1-1A with significant variation among the treatment doses as well as fungicide molecules (p ≤ 0.05). At the respective EC50 doses all four fungicides inhibited cell wall degrading enzymes viz. invertase, cellulase, polygalacturonase and pectin lyase, of the sheath blight pathogen. The extent of inhibition of the enzymes significantly varied among the fungicides. It is important to note that in spite of having common mode of action, all four triazole fungicides demonstrated significant variation in their fungicidal efficacy on R. solani Kühn AG1-1A.  相似文献   

17.
This study investigates on effects of four fungicide and six isolate from Trichoderma and Gliocladium on Botrytis cinerea agent grey mold of strawberry under library and greenhouse condition. The effect of four fungicides i.e. benomyl, dichlofluanid, captan and triadimenol on B. cinerea was studied in the laboratory condition by method mixed poison to culture medium. It was shown that the fungicide including benomyl, triadimenol, dichlofluanid and captan were able to inhibit mycelial growth of B. cinerea on PDA plate with EC50 of 0.16, 1.42, 3.40 and 7.73 ppm respectively. These fungicides delayed myceliogenic germination of sclerotia at 1000 ppm, while exhibiting no fungicidal effect. Moreover, the antagonistic effects of six fungi including Trichoderma koningii (T21), T. viride (T4), T. harzionum (T5), T. viride (T2), G. virens (G2), G. virens (G8) on B. cinerea were assessed. This assessment was done under library condition and its results as follows: The antagonistic mechanism occurred through branching at the end of B. cinerea hyphae, hyphal contact, coiling, vacuolization and lyses. Volatile metabolites of T. koningii (T21) and non-volatile metabolites of G. virens (G2 and G8) and T. koningii (T21) caused maximum inhibition of the fungal growth. Trichoderma spp and G. virens were able to colonize and sporulate on sclerotia and caused their lysis within 7-21 days. In greenhouse, a completely randomized design with 11 treatments (4 chemical and 6 biological and one untreated control) each replicated five times were used for the comparison. Greenhouse studies revealed that application of fungicides i.e. captan, dichlofluanid, triadimenol and benomyl reduces disease severity by 42, 45, 48 and 52% respectively. The fungal antagonists reduce the grey mold disease severity between 5-42%. All treatments caused a decline in post harvest disease, as the most effective treatment of chemical control was benomyl with 68.33% and for the biological treatment this was T. koningii (T21) with 56%.  相似文献   

18.
Pythium ultimum (Trow) is one of the main causes of damping-off disease in many parts of the world. Control of the disease depends mainly on application of chemical fungicides. However, soil treatments with fungicides are not always feasible due to economical and ecological reasons. Soil-borne, non-pathogenic bacteria of the genus Pseudomonas fluorescens with the ability to antagonise fungal phytopathogens, represent a realistic alternative to chemical fungicides and show great promise with respect to protect plant roots from fungal-induced diseases. In an attempt to find an integrated control system of damping-off disease in tomato, fungicides including azoxystrobin, metalaxyl-M and pyraclostrobin were applied alone and in combination with P. fluorescens isolate CW2. The fungicides were tested in in vitro for their antagonistic potential against P. ultimum and for compatibility with CW2. It was found that the fungicides were fungitoxic to P. ultimum, but did not inhibit the growth of the P. fluorescens. The efficacy of the fungicides alone and in combination with CW2 was also tested in greenhouse experiments against damping-off disease on tomato. Two concentrations (5 and 10?μg?ml?1) were applied. Damping-off incidence of tomato seedlings in Humosoil?:sand mixture infested with P. ultimum was reduced following seed treatment with the fungicides. However, the degree of control obtained varied significantly depending on the fungicide used. Combined seed treatment with P. fluorescens and the fungicides resulted in a significant improvement in disease control and improved plant growth as indicated by shoot and root dry weights. Metalaxyl-M treatment applied alone or in combination with P. fluorescens, significantly protected tomato seedlings against damping-off. Strobilurin fungicides stimulated plant growth compared to metalaxyl-M. Combined treatment of tomato seeds with strobilurin fungicides and CW2 showed a moderate to good disease control and an increase in shoot and root dry weights.  相似文献   

19.
This study reports the effects of long-term elevated atmospheric CO2 on root production and microbial activity, biomass, and diversity in a chaparral ecosystem in southern California. The free air CO2 enrichment (FACE) ring was located in a stand dominated by the woody shrub Adenostoma fasciculatum. Between 1995 and 2003, the FACE ring maintained an average daytime atmospheric CO2 concentration of 550 ppm. During the last two years of operation, observations were made on soil cores collected from the FACE ring and adjacent areas of chaparral with ambient CO2 levels. Root biomass roughly doubled in the FACE plot. Microbial biomass and activity were related to soil organic matter (OM) content, and so analysis of covariance was used to detect CO2 effects while controlling for variation across the landscape. Extracellular enzymatic activity (cellulase and amylase) and microbial biomass C (chloroform fumigation-extraction) increased more rapidly with OM in the FACE plot than in controls, but glucose substrate-induced respiration (SIR) rates did not. The metabolic quotient (field respiration over potential respiration) was significantly higher in FACE samples, possibly indicating that microbial respiration was less C limited under high CO2. The treatments also differed in the ratio of SIR to microbial biomass C, indicating a metabolic difference between the microbial communities. Bacterial diversity, described by 16S rRNA clone libraries, was unaffected by the CO2 treatment, but fungal biomass was stimulated. Furthermore, fungal biomass was correlated with cellulase and amylase activities, indicating that fungi were responsible for the stimulation of enzymatic activity in the FACE treatment.  相似文献   

20.
The potential of FsK, a non-pathogenic endophytic Fusarium solani strain, to be utilized as a biocontrol agent in combination with nine selected fungicides registered in tomato crops in Greece was evaluated. In vitro fungitoxicity tests revealed that FsK was insensitive to doses exceeding 100 μg/mL of thiophanate-methyl, fenhexamid, cyprodinil, boscalid and mancozeb. On the contrary, prochloraz, fludioxonil, pyraclostrobin and difenoconazole were most toxic to FsK. None of the later fungicides affected conidial production in an adverse way. Drenching of tomato plants with the above fungicides at recommended doses did not significantly affect colonization of tomato roots by FsK as revealed by in vitro isolation and Real Time PCR quantification. The disease suppressive ability of FsK against Fusarium oxysporum f.sp.radicis lycopersici (FORL) was not adversely affected by the post-inoculation application of commercial formulations of fludioxonil (Switch) and pyraclostrobin (Comet) at the recommended doses. Even more, the Comet–FsK combination resulted in enhanced disease suppression compared to either of the two treatments applied individually. In conclusion, not only biocontrol agent FsK is suitable for use in tomato integrated disease management programs that include all tested fungicides but also, some FsK –fungicide combinations can have additive effect against FORL disease incidence.  相似文献   

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