Pathogenicity of root-knot nematode,Meloidogyne incognita on Lens culinaris (Medik.)

Effects of the root-knot nematode (Meloidogyne incognita) on lentil (Lens culinaris) were studied under greenhouse conditions. The plants were inoculated with 250, 500, 1000, 2000 and 4000 J₂ per plant. Plant growth, yield, nodulation, seed weight, chlorophyll, nitrogen, phosphorus and potassium, (NPK) contents, as compared to control, were found decreased in all the nematode infected plants. The extent of reduction increased with an increase in inoculum levels. The reductions were significant at 500 J₂ and at higher inoculum levels, i.e. 1000, 2000 and 4000 J₂ per pot over the control. An increase in inoculum level caused enhancement in galling, egg mass production and nematode population. At higher inoculum levels, the population of the nematode in the root as well as in the soil increased to a greater magnitude than at lower inoculum levels. On the contrary, reproduction factor (RF) and rate of population increase (RPI) decreased with increasing inoculum levels.     

Effect of certain organic materials in controlling Meloidogyne incognita root-knot nematode infesting banana

Efficacy of certain plant wastes as onion bulb envelope, dry leaves of sugar beet, fleabane and jojoba, filter cake or mud as sugar cane industrial residue and nile fertile mineral bio-fertilisers were studied under field conditions for managing Meloidogyne incognita on banana Cv. Williams. All the tested treatments significantly (P ≤ 0.05 and 0.01) proved to be effective in reducing the studied nematode criteria during the growing season of banana. The highest percentage reductions of 87.5 and 85.5% were recorded in the number of second-stage juveniles caused by fleabane at vegetative and harvest stages, respectively. As for galls, the highest percentage reductions of 80.4 and 79.6% were achieved at harvest stage by sugar beet waste and filter cake residue, respectively. Also, sugar beet waste was the best at increasing banana fruit yield per feddan (77.0%), followed by jojoba (53.1%) and fleabane (50.4%). The number of fingers and hands per bunch increased by the different materials at various degrees.     

In vitro studies of antagonistic fungi against the root-knot nematode,Meloidogyne incognita

The present study was carried out in vitro to determine the efficacy of indigenous fungi isolated from egg masses of root-knot nematode, Meloidogyne incognita on egg parasitism, egg hatching, mobility and mortality against root-knot nematode, M. incognita. The tested fungi were Acremonium strictum, Aspergillus terreus, A. nidulans, A. niger, Chetomium aubense, Chladosporium oxysporum, Fusarium chlamydosporium, F. dimarum, F. oxysporum, F. solani, Paecilomyces lilacinus, Pochonia chlamydosporia, Trichoderma viride and T. harzianum. All tested fungi showed varied effects against the nematodes. Culture filtrates of A. strictum was very effective against the nematode in regards to egg parasitism (53%), egg hatching inhibition (86%) and mortality (68%) compared to controls. A. strictum was found to have an advantage over P. lilacinus, P. chlamydosporia, T. viride and T. harzianum in that it caused greater mortality of the second stage juveniles (J₂). A. terreus did not show egg parasitism but was found to be highly toxic against second stage juveniles (J₂) causing high mortality (around 68%). Thus, A. strictum and A. terreus showed good biocontrol potential against root-knot nematode, M. incognita under in vitro conditions.     

Impact of certain oil-seed cakes or powder in comparison with oxamyl or urea on Meloidogyne incognita infecting eggplant

A pot experiment was conducted to evaluate the influence of certain oil-seed cakes i.e. fennel, sesame, anise or plant dry seed powder of red pepper as soil amendments in comparison with oxamyl or urea on controlling Meloidogyne incognita infecting eggplant seedlings under greenhouse conditions at 27 ± 5°C. Results indicated that all tested materials significantly improved the growth of eggplant and suppressing the number of galls, females and egg masses of M. incognita as compared to nematode alone. Moreover, anise oil-cake gave the best growth of total plant fresh and dry shoot weights as percentage increase (160.8 and 64%) followed by sesame oil-cake (143.5 and 64%), respectively. However, the highest values of percentage reduction for number of galls (64.2%), females (58.5%) and egg masses (55.7%) on eggplant roots were achieved by sesame-oil-cake application, followed by anise-oil-cake treatment with values of 63.0, 59.6 and 51.1% for the same nematode criteria, respectively. Meanwhile, oxamyl or urea treatment showed remarkable reduction percentages for nematode parameters tested.     

Interactions between the root-knot nematode Meloidogyne incognita and Glomus mosseae in banana

The effects of the interaction between the arbuscular mycorrhizal fungus Glomus mosseae and the root-knot nematode Meloidogyne incognita on growth and nutrition of micropropagated ;Grand Naine banana (Musa AAA) cultivar was studied under greenhouse conditions. Inoculation with two G. mosseae isolates significantly increased growth of plants in relation to non-mycorrhizal plants. Response to mycorrhizae was as effective as with an optimum P fertilization in promoting plant development for most growth parameters. Meloidogyne incognita had no apparent effect on the percentage of root colonization in mycorrhizal plants. In contrast, G. mosseae suppressed root galling and nematode buildup in the roots. The percentage of mycorrhizal colonization was high (over 80%) in low P fertilized plants, but optimum P rates for bananas (four times higher than low P) significantly reduced mycorrhizal colonization. Most elements were within sufficiency levels for banana with exception of N which was low for all treatments. Mycorrhizal plants fertilized with a low P rate showed higher N, P, K, Ca, and Mg contents as compared to non-mycorrhizal plants low in P with or without the nematode. Inoculation with G. mosseae favours growth of banana plants by enhancing plant nutrition and by suppressing nematode reproduction and galling during the early stages of plant development.     

Histological response of resistant tomato cultivars to infection of virulent Tunisian root-knot nematode (Meloidogyne incognita) populations

The response of a susceptible tomato cultivar (Solanum lycopersicum cv. Rio Grande) to infection by three populations of root-knot nematode (Meloidogyne incognita) was compared histologically with that of Lycopersicon esculentum cv. Monita, L. esculentum cv. VFN8 and Solanum lycopersicum cv. Nemador possessing the Mi-1 resistance gene and accession PI126443 of L. peruvianum possessing the Mi-3 gene. The resistant cultivars showed susceptibility to the Tunisian Meloidogyne populations. Feeding sites were characterised by the development of giant cells that contained granular cytoplasm and several hypertrophied nuclei. The cytoplasm of giant cells was aggregated along their thickened cell walls and consequently the vascular tissues within galls appeared disrupted and disorganised. Feeding site formed on resistant L. esculentum lines and susceptible cultivar Rio Grande are similar according to cell and nucleus number, and the nurse superficies. Resistant accession L. peruvianum PI126443, known to possess heat-stable nematode resistance, also showed susceptible reaction to Tunisian Meloidogyne incognita populations; however, nematode development was reduced in comparison with susceptible plants and less developed feeding cells were observed.     

丛枝菌根真菌对不同番茄品种抗根结线虫病的影响

【背景】根结线虫病害严重制约我国设施蔬菜的生产。丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)作为土壤中最重要的有益真菌之一,可以促进植物生长,提高植物抗病性,减轻土传真菌和线虫病害的发生。在蔬菜保护地栽培中,AMF对于植物线虫病防治作用的研究受到了广泛关注。【目的】针对番茄生产中危害最严重的南方根结线虫(Meliodogyne incognita)病害问题,研究AMF和番茄品种不同组合的抗线虫效应,以期为菌根真菌作为生物防治剂和生物菌肥应用于实际生产提供技术基础。【方法】在灭菌土壤中,人工接种根结线虫,比较不同菌种Rhizophagus intraradices(Ri)、Acaulosporamellea(Am)及菌种组合Rhizophagusintraradices+Acaulosporamellea(Ri+Am)在不同番茄品种(感病品种蒙特卡罗和抗线虫品种仙客1号)上对南方根结线虫侵染和繁殖的影响,研究AMF对根结线虫的拮抗效应。另外,采用南方根结线虫连作发病的土壤,在感病品种蒙特卡洛上接种AMF混合菌种Ri+Am,番茄苗移栽入连作土壤中,测定各生长指标和调查根结和卵块数量,评价接种AMF处理对根结线虫病的防治效果。【结果】在灭菌土壤中,普通番茄品种蒙特卡罗的菌根效应显著优于抗线虫番茄品种仙客1号,表现为前者单位根重的根结和卵块的数量均比对照显著降低,而后者仅降低了卵块数量;蒙特卡罗上接种Ri+Am混合菌种的效果优于接种单一菌种Am和Ri;而仙客1号上接种Ri的效果更好。接种线虫也显著影响了AMF的侵染,而且对抗性品种仙客1号的影响更为明显。但除了接种Am的处理,大多数处理收获时菌根侵染率仍维持较高的水平(70%以上)。在连作土壤中,感病品种蒙特卡罗接种混合菌种Ri+Am具有较好的抗/耐线虫效应,主要表现为促进植株生长,显著降低根结和卵块数量,但菌根侵染率较灭菌土壤低,约为40%。【结论】综合以上结果,表明菌根化苗能够在一定程度上减轻根结线虫病的危害。土壤灭菌条件下,在感病和抗线虫番茄品种上接种AMF能够减轻线虫的侵染和繁殖,而且在感病品种上的防治效果更加显著。在连作土壤中,在番茄感病品种上接种AMF也表现较好的抗线虫效果。     

Pathogenic potential of root-knot nematode Meloidogyne incognita and root-rot fungus Fusarium solani on chilli (Capsicum annuum L.)

Damaging threshold levels of root-knot nematode Meloidogyne incognita and root-rot fungus Fusarium solani on plant growth parameters, viz., plant length, fresh and dry weight of chilli were determined by conducting their pathogenicity trials in pot experiments. The results revealed a significant reduction in the plant growth parameters at and above the inoculum level of about 1000?J₂ per plant of M. incognita and the highest reduction was recorded at 8000?J₂ per plant. Significant reduction in plant growth parameters was recorded at 1.00?g mycelial mat of F. solani per plant, while the highest reduction was observed at 8.00?g mycelial mat per plant. The damaging threshold level was 1000?J₂ per plant of M. incognita and 1.00?g mycelial mat of F. solani.     

Influence of cadmium on penetration of the root-knot nematode,Meloidogyne incognita and plant growth parameters of tomato

The results of experiment clearly reveal that cadmium inhibited root penetration by the second stage juveniles (J₂) of Meloidogyne incognita which subsequently affected the development of root galls in tomato. The heavy metal was highly injurious to tomato plants at all the concentrations tested for (7.5, 15.0, 30.0 and 60.0?ppm). The inhibitory effect on plant growth and other parameters (fresh and dry weight of plant, chlorophyll content of leaves, water absorption capability of roots) significantly increased with an increase in the concentration of the metal. It was further increased in the presence of the nematode.     

The role of chitinase from Lecanicillium antillanum B-3 in parasitism to root-knot nematode Meloidogyne incognita eggs

B-3 fungal isolate was isolated from soil samples of Gwangju in Korea. Based on morphological and phylogenetic analysis, it was designated as Lecanicillium antillanum B-3 (syn. Verticillium antillanum B-3). The fungus was a chitinolytic-nematophagous microorganism. B-3 chitinase activity from 0.5% swollen chitin broth medium reached the highest level on the sixth day and then plateaued until 12 days. B-3 isolate showed the high rate of parasitism on Meloidogyne incognita eggs with more than 90% infection rate on the third day after treatment. B-3 crude chitinase damaged the eggshell structures more than 78% based on lactoglycerol staining data at a final protein concentration of 14.6 µg mL^?1 on the fourth day following treatment. Partially purified chitinase with molecular 37 kDa from DEAE-Sephadex chromatography also showed damaging effect on the eggs. These results suggested that chitinase from B-3 isolate was responsible for degradation of M. incognita eggshell structures.     

Effects of Eclipta alba on the morphometrics of root-knot nematode,Meloidogyne incognita as influenced by fly ash amended soil

An experiment in a complete randomised design was conducted with the aim of investigating the impact of graded quantities (10, 20, 30, 40 and 50%) of fly ash on the morphometrics of root-knot nematode, Meloidogyne incognita (2000 J₂/pot) in Eclipta alba. The application of fly ash brought about deleterious effects on the development of the nematode which were reflected on dimensions of the mature females in all the fly ash concentrations over the inoculated control (IC). Significant reductions in length and width of body, neck, stylet and median bulbs of the mature females were recorded at higher (40 and 50%) fly ash levels, when compared with inoculated control (IC). The severity of root-knot disease was found to be decreased with increasing fly ash concentrations.     

Control of root-knot nematode,Meloidogyne incognita and reniform nematode,Rotylenchulus reniformis on pigeonpea and linseed

Abstract

Pigeonpea (Cajanus cajan) and linseed (Linum usitatissimum) are susceptible to Meloidogyne incognita and Rotylenchulus reniformis nematodes. Reduction in different growth parameters (length and weight of plant, number of pods), bulk density of pigeonpea stem, oil content of linseed, chlorophyll content of leaf and water absorption of roots caused by M. incognita and R. reniformis were statistically significant. Similar effects were also observed in plants raised from seeds soaked in different concentrations of water soluble fractions (WSF) of rice polish and pyridoxine solutions, however, the reductions were of a comparatively lesser extent. Higher concentrations of the solutions were more effective when compared to lower ones and pyridoxine was more beneficial than WSF for improving plant growth and reducing disease incidence.     

Differential expression of root-knot nematode resistance genes in tomato and pepper: evidence with Meloidogyne incognita virulent and avirulent near-isogenic lineages

Reproduction of artificially selected near isogenic Meloidogyne incognita lineages virulent and avirulent against the Mi resistance gene of tomato was assessed on host and resistant lines and cultivars of pepper. Egg mass production following inoculation of individual potted seedlings with second-stage juveniles was studied in experiments conducted in controlled environment. Artificially selected Mi-virulent nematode populations were unable to develop on resistant pepper lines PM 217 and PM 687. This suggests that the genetic systems governing resistance to root-knot nematodes are differently expressed in tomato and pepper, in spite of the very close phylogenetic relationships and structural genomic homologies occurring between these two vegetable crops. Moreover, these artificially selected nematode populations were also found unable to develop on the susceptible pepper cultivars California Wonder and Doux Long des Landes, while their pathogenicity was not significantly affected on susceptible tomatoes. Due to the existence of naturally virulent Meloidogyne populations, these results enhance the need for a better understanding of the mechanisms involved, in order to develop new forms of management of plant resistance to root-knot nematodes.     

Interactive effect of root-knot nematode,Meloidogyne incognita and root-rot fungus,Rhizoctonia solani,on okra [Abelmoschus esculentus L.]

The individual, concomitant and sequential inoculation of second stage juveniles (at 2000 J₂/kg soil) of Meloidogyne incognita and Rhizoctonia solani (at 2 g mycelial mat/kg soil) showed significant reduction in plant growth parameters viz. plant length, fresh weight and dry weight as compared to control. The greatest reduction in plant growth parameters was recorded in the plants simultaneously inoculated with M. incognita and R. solani followed by sequential and individual inoculation. In sequential inoculation, plant inoculated with M. incognita 15 days prior to R. solani shows more reduction in comparison to plant inoculated with R. solani 15 days prior to M. incognita. Moreover, the multiplication of nematode and number of galls/root system were significantly reduced in concomitant and sequential inoculation as compared to individual inoculation, whereas the intensity of root-rot/root system caused by R. solani was increased in the presence of root-knot nematode M. incognita as compared to when R. solani was inoculated individually.     

Mode of action and efficacy of iprodione against the root‐knot nematode Meloidogyne incognita

The ban and restriction on the use of several synthetic chemicals for controlling plant parasitic nematodes, and concern about their side effects necessitate the availability of effective methods of control with low toxicity to humans and non‐target organisms. Therefore, efficacy and mode of action of iprodione, a dicarboximide fungicide, was evaluated against the root‐knot nematode Meloidogyne incognita, in vitro and in vivo conditions, in comparison with the nematicides fenamiphos, fosthiazate and oxamyl at 7.00, 1.66 and 1.66 mL/5 L water, respectively. In vitro, iprodione showed nematostatic rather than nematicidal activity against second‐stage juveniles of M. incognita in contrast to fenamiphos, fosthiazate and oxamyl which were nematicidal. In the in vivo experiment with tomato, iprodione controlled M. incognita less than fenamiphos, fosthiazate and oxamyl. No visual symptoms of phytotoxicity were observed. Therefore, iprodione can be a useful chemical for controlling nematode populations if included in an Integrated Pest Management program.     

Effect of Nodularia harveyana biomass on the incidence of root-knot nematode (Meloidogyne incognita) in tomato

An acetone extract of Nodularia harveyana wasshown to be toxic to the free-living nematode Cephaloboides oxycerca. This antagonistic effect wastested in pot culture trials with lyophilized biomasson gall induction by the root-knot nematode Meloidogyne incognita, using different methods ofapplication of the cyanobacterial biomass to thetomato plants. The trials revealed a possibleutilization of biomass of this cyanobacterium as aprotection agent against this phytoparasite.     

银胶菊叶和花提取物对南方根结线虫的毒杀活性比较

为进一步明确银胶菊(Parthenium hysterophorus L.)的杀线虫活性,对银胶菊叶和花的不同溶剂提取物、甲醇提取物的不同萃取物以及甲醇提取物碱水层的不同极性组分对南方根结线虫(Meloidogyne incognita Chitwood)的杀虫活性进行了检测,并对不同提取物、萃取物和萃取组分进行了生物碱的定性分析.结果表明:银胶菊叶和花的蒸馏水、甲醇、乙酸乙酯和石油醚提取物的得率分别为24.5％和20.3％、19.6％和10.9％、6.8％和7.7％、2.0％和2.7％,其中,叶和花的蒸馏水和甲醇提取物的杀线虫活性均较强,而石油醚提取物的杀线虫活性最弱.用质量体积分数1.0％和0.5％的叶和花蒸馏水提取物分别处理24和48 h后试虫的校正死亡率均达到100.00％;用质量体积分数1.0％和0.5％的叶和花甲醇提取物处理48 h,试虫的校正死亡率均大于90％.叶和花甲醇提取物的碱水层、三氯甲烷Ⅰ层和Ⅱ层萃取物均具有一定的杀线虫活性,其中,用质量体积分数1.0％的花和叶碱水层萃取物以及花的三氯甲烷Ⅰ层萃取物分别处理48 h,试虫的校正死亡率均为100.00％,而三氯甲烷Ⅱ层萃取物的杀线虫活性最弱.银胶菊叶和花甲醇提取物碱水层的11个不同极性组分(A1～A11)也表现出不同程度的杀线虫活性,其中,用质量体积分数0.2％和0.1％花的A2[溶剂为V(三氯甲烷)∶V(甲醇)=10∶1]和A7[溶剂为V(三氯甲烷)∶v甲醇)=1∶1]组分以及叶的A2和A6[溶剂为V(三氯甲烷)∶V(甲醇)=2∶1]组分处理48 h后,试虫的校正死亡率均达100.00％,显著高于其他组分.定性实验结果表明:银胶菊叶和花中具有杀线虫活性的提取物、萃取物和萃取组分中均含有生物碱.研究结果说明:银胶菊花的杀线虫活性高于叶片,其毒杀活性不仅与提取部位及溶剂的种类和极性有关,还与提取物浓度及作用时间等因素有关.     

Nematicidal activity of Okinawa Island plants on the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood

In order to develop biological control methods that are effective against the root-knot nematode Meloidogyne incognita (Kofoid and White) chitwood, the activity of ethanolic and aqueous extracts of wild plant species distributed on Okinawa Island on the viability and mobility of second stage M. incognita juveniles (J2s) was evaluated. Eleven of the 29 extracts immobilized at least half of the J2 stage nematodes in an in vitro assay. Aqueous extracts of Bidens pilosa L. var. radiata Scherff, Hydrocotyle dichondroides Makino, Oxalis corymbosa DC., Oxalis corniculata L., and Stenactis annus (L.) Cass gave 90% or better immobilization activity. Among these, B. pilosa var. radiata had the highest activity. Significant immobilization, lethality, repellence and egg hatching inhibition were observed with extracts from each B. pilosa plant part, but especially from leaves. The effects of plant extracts on the mobility of M. incognita were higher than on the free-living nematode Panagrolaimus sp., suggesting that M. incognita could be suppressed using B. pilosa extracts without significantly affecting beneficial nematodes.     

Bio-activity of fungal culture filtrates against root-knot nematode egg hatch and juvenile motility and their effects on growth of mung bean (Vigna radiata L. Wilczek) infected with the root-knot nematode,Meloidogyne incognita

Culture filtrates of selected soil fungi, namely Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium oxysporum, Penicillium vermiculatum and Rhizopus nigricans exhibited variable response to egg hatching and mortality of the root-knot nematode, Meloidogyne incognita. Higher concentrations of the culture filtrates of all the fungi inhibited egg hatching and proved to be toxic to the juveniles of M. incognita. In addition, development of the gall and multiplication of M. incognita were also found adversely affected in varying degrees on all the plants of Vigna radiata treated with the filtrates. The culture filtrate of A. niger showed highest toxicity to the nematode than those of any other fungus tested. Soil drench application of the culture filtrates gave better seedling growth and least nematode multiplication in comparison to seed soaking treatment.