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1.
采用前期筛选出的对黄瓜枯萎病菌有较好拮抗作用的3株木霉菌,即哈茨木霉菌(Trichoderma harzianum)809、拟康氏木霉菌(Trichoderma pseudokoningii)886和棘孢木霉菌(Trichoderma asperellum)525,利用盆栽试验,测定了木霉菌分生孢子和厚垣孢子对黄瓜幼苗抗氧化能力及对枯萎病防效的影响。结果显示:3株木霉菌分生孢子和厚垣孢子对黄瓜枯萎病的盆栽防效均在66.81%以上,且以拟康氏木霉菌886厚垣孢子防效最高,达到81.46%;当黄瓜幼苗长至三叶一心时,与CK(即只接种病原菌)相比,经哈茨木霉菌809、拟康氏木霉菌886、棘孢木霉菌525分生孢子以及厚垣孢子处理后,黄瓜幼苗叶片相对电导率和丙二醛(MDA)含量均呈下降趋势,而保护性酶包括过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、超氧化物歧化酶(SOD)活性则呈上升趋势,其中以拟康氏木霉菌886厚垣孢子的变化幅度最显著;拟康氏木霉菌886厚垣孢子处理的黄瓜幼苗叶片相对电导率、MDA含量分别比CK下降了47.74%、41.40%;而叶片中的POD、CAT、APX、SOD活性则分别比CK增加了318.11%、155.36%、157.09%和300.34%。研究表明3株木霉菌分生孢子和厚垣孢子均能通过改善黄瓜幼苗叶片抗氧化能力,增加保护酶活性,提高了对黄瓜枯萎病的防治效果。  相似文献   

2.
Pythium spp. that cause damping-off of seedlings also can cause root rot of older plants and lead to yield reductions. This can be especially severe in soilless cultures where the fungus can spread easily with the nutrient solution. 39Pythium isolates obtained from discolored roots were assayed for their ability to cause damping-off on cucumber seedlings in sand-peat and for their pathogenicity in soilless culture of cucumber in rockwool or hydroponic solution. Isolates ofPythium aphanidermatum, P. irregulare, P. sylvaticum andP. ultimum were highly pathogenic in sand-peat, but onlyP. aphanidermatum strains were pathogenic in soilless conditions and led to root decay, plant death in rockwool culture and growth reduction in hydroponic culture. One strain ofP. aphanidermatum significantly reduced the yield of cucumber grown in rockwool under conditions similar to those of commercial cultures.  相似文献   

3.
采用前期筛选出的对黄瓜枯萎病菌有较好拮抗作用的3株木霉菌,即哈茨木霉Trichoderma harzianum 809、拟康氏木霉Trichoderma pseudokoningii 886和棘孢木霉Trichoderma asperellum 525,利用盆栽试验,测定了木霉菌孢子不同类型施用对黄瓜幼苗生长、生理特性及枯萎病防效的影响。结果表明:哈茨木霉809、拟康氏木霉886、棘孢木霉525分生孢子和厚垣孢子对黄瓜枯萎病的盆栽防效均在66.81%以上,且以拟康氏木霉886厚垣孢子防效最高,达到81.46%。当黄瓜幼苗长至三叶一心时,3株木霉菌分生孢子和厚垣孢子处理的黄瓜幼苗株高、茎粗、根体积、叶面积、全株鲜质量均比CK显著上升,以厚垣孢子886的促进效果最显著,其株高、茎粗、根体积、叶面积、全株鲜质量分别较CK增加了85.33%、108.43%、235.29%、144.38%、272.32%。同时,3株木霉菌分生孢子和厚垣孢子处理的黄瓜幼苗叶绿素含量、根系活力、叶片可溶性糖含量、叶片可溶性蛋白含量也均比CK显著上升,厚垣孢子886的促进效果仍最显著,其叶绿素含量、根系活力、叶片可溶性糖含量、叶片可溶性蛋白含量分别较CK增加了97.47%、86.05%、172.49%、201.91%。  相似文献   

4.
Conidia of sevenTrichoderma strains were applied on cucumber or radish seeds as a simple methyl cellulose coating or through an industrial film coating process. The seeds were sown in a peat-based soil artificially infested byR. solani orP. ultimum. Four strains controlled damping-off caused byR. solani when applied as a simple coating or as an industrial film-coating. Also, four strains significantly reduced damping-off caused byP. ultimum in cucumber. A correlation was found between production of volatile antibiotics in vitro and control ofP. ultimum. Survival during storage varied according to the strain. Better survival was observed for two strains, with a decrease in conidial viability of one order of magnitude after storage for three and five months at 15 ° C and 4 ° C, respectively. The results show the feasibility of biocontrol of seedling diseases by some antagonists applied onto seeds through an industrial film-coating process.  相似文献   

5.

Chitinase-producing Trichoderma species have been recognized long ago against the phytopathogenic fungi. In this study, we evaluated the production of chitinase enzyme for seventeen isolates of Trichoderma isolated from onion growing districts of Punjab and assessed their bio-efficacy against damping-off in onion. In vitro, these Trichoderma isolates were screened for their antagonistic activity against the damping-off pathogen Fusarium oxysporum f.sp. cepae by dual culture assay. These isolates were also screened for their chitinase enzyme activity; it was found that isolates T5 and T8 are showing higher antagonistic activity on Fusarium oxysporum f.sp. cepae and also produced large amounts of chitinase enzymes in the presence of commercial colloidal chitin. The selected chitinolytic isolates were used in field studies to confirm the feasibility of their biological control efficacy against onion damping-off. In the field experiment, the seed+soil treatment of chitinolytic isolate (T8) showed a critical decrease of damping-off in onion by 88.75% over control.

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6.
Twenty isolates of fluorescent pseudomonads were evaluated for their ability to control damping-off in tomato (Lycopersicon esculentum) and hot pepper (Capsicum annuum). These isolates were characterized as Pseudomonas fluorescens and Pseudomonas putida. Two isolates, PFATR and KKM 1 belonged to P. putida and the remaining 18 isolates belonged to P. fluorescens. Among these isolates, P. fluorescens isolate Pf1 showed the maximum inhibition of mycelial growth of Pythium aphanidermatum and increased plant growth promotion in tomato and hot pepper. P. fluorescens isolate Pf1 was effective in reducing the damping-off incidence in tomato and hot pepper in greenhouse and field conditions. Isolate Pf1 was further tested for its ability to induce production of defense-related enzymes and chemicals in plants. Earlier and increased activities of phenylalanine ammonia lyase (PAL), peroxidase (PO) and polyphenol oxidase (PPO) were observed in P. fluorescens Pf1 pretreated tomato and hot pepper plants challenged with Pythium aphanidermatum. Moreover, higher accumulation of phenolics was noticed in plants pretreated with P. fluorescens isolate Pf1 challenged with Pythium aphanidermatum. Thus, the present study shows that in addition to direct antagonism and plant growth-promotion, induction of defense-related enzymes involved in the phenyl propanoid pathway collectively contributed to enhance resistance against invasion of Pythium in tomato and hot pepper.  相似文献   

7.
Three strains ofPseudomonas fluorescens (63-49, 63-28, and 15), one strain ofPseudomonas corrugata (13) and one strain ofSerratia plymuthica (R1GC4) were tested on rockwool-grown cucumbers for their ability to reduce Pythium root-rot caused byPythium aphanidermatum. These strains were previously selected for biocontrol ability from collections of >4000 bacteria. Strains 63-49 and 63-28 were tested on cucumber plants grown in rockwool in two replicatedPythium-inoculated trials conducted in British Columbia (B.C). Another inoculated, replicated trial was conducted in Quebec with all five strains. Cucumber yields (fruit number and weight) were measured over a ten-week harvest period. Strain 63-49 caused an early promotion of plant growth and increased cucumber yields at early harvests. No measurable effect ofPythium inoculation on disease development was observed in the Quebec trial, due to unfavourable cool weather. However, 63-49 significantly increased the total number of cucumbers (12%) and cucumber weight (18%), compared to the non-treated control. Strains 13, 15 and R1GC4 slightly increased the cumulative cucumber yields, but strain 63-28 had no effect. In the B.C. trial, inoculation withP. aphanidermatum reduced the number and weight of cucumbers by 27%. Treatments ofPythium-inoculated cucumbers with 63-49 significantly increased fruit number and weight by 18%, compared to thePythium-inoculated control. Strain 63-28 increased the cumulative number of cucumbers over time, compared to thePythium-inoculated control, but the increase was less than with 63-49. The use ofPseudomonas spp. in rockwool-grown cucumbers can increase yields, both in the presence and absence of Pythium root rot, and with variable seasonal conditions and disease pressures.  相似文献   

8.
Eight newBacillus thuringiensis Berliner (Bt) isolates originally recovered from different source materials and geographic locations in Kenya were tested againstChilo partellus (Swinhoe) on sorghum grown in a greenhouse. All isolates had been demonstrated previously to be toxic to this pest.Bt strains were cultured in a liquid growth medium and preserved as powders for experimental application. Three-week-old sorghum plants (4-6 leaves) were artificially infested with 20 neonateC. partellus and sprayed 24 h later withBt suspensions. Non-infested sorghum and infested non-treated sorghum served as the comparative checks within each experimental trial. Plant development and dead-heart formation were monitored up to harvest; at harvest, grain yield was recorded. In each replicate trial, all of theBt strains tested reduced plant damage consistently, compared with the infested, non-treated checks. Dead-heart formation was significantly reduced and grain yields were significantly higher. Three novel isolates, A-3, A-C-2 and M44-2, provided superior levels of protection throughout. Statistically, there was no difference among these threeBt treatments and the non-infested check in terms of the number of dead-hearts (i.e., non-yielding plants) that formed during the course of the experiment. In the infested, non-treated check plots, dead-hearts developed in 74.5±10.0% of the plants, compared with only 3.1±1.2% of the non-infested plants, and 3.1 ±1.5%, 6.2±2.0% and 6.2±2.0% of the plants treated with M44-2, A-3 and A-C-2, respectively. At harvest, the weight of grain obtained from the non-infested control plots was considered to be 100% of the potential yield for each experimental replicate. In the infested, non-treated controls, only 14±5.6% of the potential yield was realized. When isolates M44-2, A-3 and A-C-2 were applied, proportionate yields of 83±5.4%, 93±2.3% and 98±1.2%, respectively, were obtained. Results showed that theBt strains selected may have a strategic role to play in the management ofC. partellus, providing applications are timed to target young larvae feeding in the leaf whorl.  相似文献   

9.
Damping-off and stem rot disease-causing Sclerotium rolfsii has been reported as a destructive soil-borne pathogen of numerous crops, especially in the tropics and subtropics. Trials were conducted to test the efficacy of biocontrol agents alone or combined with Moringa oleifera leaf extracts for the control of the disease. In the laboratory, PDA was amended with Moringa leaf extract, and mycelial growth of S. rolfsii was measured. In the greenhouse and field, Trichoderma Kd 63, Trichoderma IITA 508 and Bacillus subtilis were evaluated as seed treatments, soil drench or sprinkle, separately or combined with Moringa leaf extracts. Percentage disease incidence, severity and control were recorded. In the laboratory, the higher the extract concentration the less the mycelial growth and no mycelial growth occurred on extract at 15 or 20 g leaves 10 ml−1 water. In the greenhouse, the highest disease control was observed at a Moringa extract concentration of 15 kg leaves 10 l−1 water (w/v). Seed treatments using Trichoderma Kd 63, and soil sprinkle using Trichoderma IITA 508 had a significantly (P = 0.05) higher effect on a disease incidence than Bacillus. Disease severity followed the same pattern. Moringa seed treatment combined with Trichoderma soil sprinkle resulted in significantly more than 94% and 70% disease control in the greenhouse and field, respectively, with significant yield increase in the field. This is the first report of Moringa leaf extract combined with Trichoderma as an integrated control for Sclerotium damping-off and stem rot of cowpea in the field.  相似文献   

10.
In the current study, the performance of three endophytic actinomycetes identified as Actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis previously shown to reduce seedling damping-off, and root and crown rots of mature cucumber (Cucumis sativus) caused by Pythium aphanidermatum in pots under greenhouse conditions were further evaluated to determine their potential as biological control agents and as plant growth promoters in the field under the conditions of commercial production of cucumbers in the United Arab Emirates (UAE). When applied individually or in combination to cucumber seedlings, the three isolates significantly promoted plant growth and yield and reduced seedling damping-off and root and crown rots of mature cucumber plants. Individually the performance level of S. spiralis was relatively the best followed by A. campanulatus and then by M. chalcea. The three isolates (which were not inhibitory to each other) performed better, both as biological control agents as well as plant growth promoters, when applied together than when they were inoculated individually. The ability of these three isolates to colonize the internal tissues of roots, stems and leaves under field conditions, and to persist up to 8 weeks after seedling inoculation, showed that they can easily adapt to an endophytic habit systemically within healthy cucumber plants. As the three endophytic actinomycete isolates also colonized the rhizosphere and showed outstanding rhizosphere competency it is clear that they are facultative and not obligate endophytes. The success with the three inoculants indicated that they could well be used in place of the fungicide metalaxyl which is currently recommended for the management of Pythium diseases in the UAE. This is the first successful field use of endophytic actinomycetes as promising plant growth promoters and biological control agents against Pythium diseases of cucumber.  相似文献   

11.
土传黄瓜立枯病高效拮抗菌的筛选鉴定及其生物效应   总被引：2，自引：1，他引：1  
采用平板对峙法从黄瓜根际土壤中分离出的400余株细菌菌株中筛选出16株对立枯丝核菌Rhizoctonia solani具有拮抗效果的菌株,抑菌带直径在0.81～1.93 cm之间。并从中选出3株抑菌带直径在1.6cm以上的菌株N33、N35和N43,结合形态、生理生化特性及16S rDNA序列比对分析,鉴定N33菌株为假单胞菌属Pseudomonas sp.,N35和N43菌株为芽胞杆菌属Bacillus sp.。通过在黄瓜育苗基质中添加选育的高效拮抗菌株,观测其对黄瓜苗生长的促进作用以及对立枯病的防治作用,3株菌株均具有促进黄瓜苗期生长和防治苗期立枯病的作用,其中N43菌株促生及防病效果均最显著,地上部鲜重比对照处理增加62.16%,防治效果达62%。  相似文献   

12.
In October 2004, Pythium ultimum var. ultimum was isolated from rotten stems of cabbage plug seedlings in a commercial nursery in Mie Prefecture (Japan). The isolated fungus was then used to inoculate seedlings and subsequently reisolated from the seedlings with the damping-off disease, showing that P. ultimum var. ultimum is a new pathogen causing cabbage seedling disease.  相似文献   

13.
The objective was to identify and characterize the causal agent of foliar necrosis and leaf scorch of Eucalyptus spp. in Brazil. Nineteen putative isolates of Rhizoctonia obtained from Eucalyptus plants during clonal propagation were compared with isolates from other hosts and with tester strains of anastomosis groups of Rhizoctonia solani. Features compared were morphological characteristics of anamorphs and teleomorphs, numbers of nuclei per cell in the vegetative hyphae, anastomosis of hyphae, and ability to produce necrotic lesions on cuttings and damping-off of E. grandis×E. urophylla hybrid seedlings. Rhizoctonia solani AG1 (AG1-IB like) was the most frequent causal agent isolated from Eucalyptus plants and cuttings with symptoms of leaf scorch and foliar necrosis respectively. These isolates were highly virulent on Eucalyptus cuttings and presented naturally epiphytic growth on Eucalyptus shoots. Binucleate isolates and isolates of R. solani AG4 were also virulent on cuttings and were most virulent on Eucalyptus seedlings causing pre- and post-emergence damping-off. Virulence on Eucalyptus cuttings and seedlings was not restricted to a single species or anastomosis group of Rhizoctonia.  相似文献   

14.
Three isolates of binucleateRhizoctonia (BNR) were tested for biological control of damping-off of cucumber seedlings caused byRhizoctonia solani AG 2-2 and AG 4. BNR isolates L2 (AG Ba) and W1 and W7 (AG A) provided protection of 58 to 71% against virulent isolate C4 of AG 4 and 64 to 75% protection against virulent isolate RH 65 of AG 2-2. Varying protection was provided to the seedlings by the BNR isolates against the virulentR. solani from the two AGs depending on their combination. The BNR isolates did not vary in providing protection to the seedling when tested against virulent C4 when both isolates were inoculated using three different methods,viz. in water agar, combination of water agar and soil and using soil alone. Protection of 58 to 71 % was provided by the isolates when inoculation was done on the hypocotyl using water agar, 62.8 to 75% using the combination of water agar and soil, and 75 to 85% when inoculation of both isolates was done in soil. Pre-incubation of BNR W7 or delayed inoculation of C4 (from 0.5 day to longer duration) using the different methods provided an increased protection to the seedlings to give complete inhibition of damping-off disease. Simultaneous inoculation of both BNR W7 and C4 using the three methods failed to provide protection to the seedlings. Among the BNR isolates, BNR W7 showed plant growth promotion in terms of significant increase in plant height (P=0.01) and fresh weight (P=0.05).  相似文献   

15.
Five Pythium species (Pythium irregulare, P. mamillatum, P. myriotylum, P. spinosum and P. ultimum var. ultimum) were isolated from the hypocotyls and roots of kidney bean plants with damping-off from a commercial field and from experimental plots that have undergone either continuous cropping with kidney bean or rotational cropping with arable crops. In inoculation tests, all five Pythium species were pathogenic to kidney bean. This is the first report of damping-off of kidney bean caused by Pythium species; we named this disease damping-off of kidney bean. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession numbers AB291811, AB291944 and AB291945.  相似文献   

16.
Rhizoctonia solani AG 2-1 was recorded in Central Italy on kohlrabi plants showing root and stem rot. After artificial inoculation the fungus caused damping-off of 7-day-old seedlings and root and stem rot of 4-month-old plants developed after 15 days of incubation. This seems to be the first record ofR. solani AG 2-1 on kohlrabi.  相似文献   

17.
Artificial suppression of radish damping-off disease was induced by repeated soil inoculations with Rhizoctonia solani, binucleate Rhizoctonia (BNR) and Sclerotium rolfsii in pot systems. Soils repeatedly inoculated with R. solani and BNR showed suppressive to disease caused by R. solani and S. rolfsii, while soils repeatedly inoculated with S. rolfsii were suppressive to disease caused by S. rolfsii but not by R. solani. Species of Trichoderma were consistently isolated from soils repeatedly inoculated with R. solani, BNR and S. rolfsii. These Trichoderma spp. accumulated selectively in relation to the fungal species that was repeatedly added to the soils. The ratios of the frequencies of T. viride, T. harzianum and T. hamatum were 5:2:2 and 8:5:2 in soils repeatedly inoculated with R. solani and BNR, respectively. In S. rolfsii- inoculated soils, T. koningii was predominantly isolated. T. viride, T. harzianum and T. hamatum isolates obtained from either R. solani or BNR after repeated additions to the soils suppressed radish damping-off disease caused after challenge inoculations with R. solani or S. rolfsii. Among the Trichoderma species, T. viride consistently yielded high levels of suppression. However, isolates of T. koningii obtained from S. rolfsii-infested soils suppressed disease caused by S. rolfsii but failed to suppress disease caused by R. solani. Generally, the species of Trichoderma accumulated in a selective pattern that was closely related to the species of fungal pathogen used to induce the suppressive soil.  相似文献   

18.
A leaf spot disease of scarlet sage (Salvia splendens Sellow ex J.A. Shultes) found in Kanagawa and Tokyo prefectures was demonstrated to be caused by Corynespora cassiicola (Berk. and Curt.) Wei based on inoculation experiments, and morphological identification of the pathogenic fungus. Isolates of C. cassiicola from cucumber, green pepper, and hydrangea were also pathogenic to scarlet sage leaves. Although the isolates from cucumber, green pepper, and hydrangea were pathogenic to scarlet sage leaves, the scarlet sage isolate was not pathogenic to cucumber, green pepper, hydrangea, eggplant, tomato or soybean.  相似文献   

19.
Phytophthora capsici infection of chili pepper seedlings can cause substantial losses due to damping-off and collar rot diseases. Chemical control is no longer effective due to reported resistance development, on top of the related environmental concerns and the consumer demands for reduced use of fungicides. Biological control is a sustainable option, with several agents having been reported to be effective against this pathogen. This research focused on optimizing the application of strain THSW13 of Trichoderma hamatum and a bacterial isolate BJ10–86 with the objectives of improving chili pepper seed germination, reduce damping-off disease incidence, and improve the growth of the seedlings. Bacterial isolate BJ10–86 was subjected to molecular identification and found to be Pseudomonas aeruginosa. Chili pepper seeds treated with the biocontrol agents, individually or in combination, were seeded into commercial nursery media that had been pre-inoculated with P. capsici zoospores. Over a period of 35 days the chili pepper seed treatments significantly (P = 0.008) reduced the disease incidence of seedlings damping-off. Combined application of T. hamatum and P. aeruginosa was the best biocontrol treatment with an area under disease curve of only 36.61 units compared to 92.87 units for the control treatment. Similar results were observed in vitro where T. hamatum and P. aeruginosa synergistically inhibited P. capsici growth by 73.2 %. The inhibition activity of this treatment was similar to mefenoxam treatment, which implies that it is an effective and sustainable alternative for chili pepper seed treatment. The biocontrol seed treatment had no effect on seed germination and seedling growth.  相似文献   

20.
黄瓜立枯病是由立枯丝核菌（Rizoctonia solani,简称Rs）侵染引起的苗期土传病害。本研究采用前期筛选获得的对黄瓜立枯病菌Rs具有较强拮抗作用的木霉菌,分别为棘孢木霉Trichoderma asperellum 437、哈茨木霉T.harzianum 670和752,通过盆栽试验和田间试验,测定对黄瓜幼苗的生长和生理特性、产量、品质以及立枯病防效的影响。结果显示：3株木霉菌均能显著促进黄瓜幼苗的生长,提高黄瓜幼苗的生理活性和保护性酶活性,对黄瓜立枯病的防效均在75%以上;木霉菌处理的黄瓜幼苗株高、茎粗、叶面积、根体积、全株鲜重、叶绿素含量、硝酸还原酶活性、根系活力、根系总吸收面积,以及抗逆性酶活性包括超氧化物歧化酶、过氧化物酶、过氧化氢酶、多酚氧化酶均显著高于对照。木霉与病原菌Rs共同处理的黄瓜幼苗,上述生长和生理生化指标均显著高于病原菌Rs单独处理。其中木霉670处理的黄瓜幼苗各项检测指标高于木霉437和752。此外,木霉菌处理的黄瓜单瓜重、产量、可溶性固形物含量、可溶性糖含量、Vc含量、可溶性蛋白含量均不同程度的增加。上述结果说明,本研究的3株木霉菌通过提高黄瓜幼苗生理特性和保护性酶活性,促进了幼苗生长,提高了对黄瓜立枯病的抗性,改善了黄瓜产量和品质。  相似文献   

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