جستجوی مقالات مرتبط با کلیدواژه "نماتد گره ریشه" در نشریات گروه "گیاهپزشکی"

The root-knot nematodes (Meloidogyne spp.) are the most important group of plant parasitic nematodes in terms of economic damage to agricultural products. Biological control is one of the new and environmentally friendly methods to control of these pathogens. One way of biological control of nematodes is the use of anti-nematode plants. In the present study, the effect of Datura stramonium, Datura metel and Hyoscyamus niger extracts was evaluated against native nematode population of Meloidogyne javanica. Evaluations were based on the effect of extracts on nematode egg hatching and mortality of second stage juveniles (J2s) in laboratory conditions. For this purpose, the plants were cultured in the phytotron and the leaves of grown plants were harvested and dried. The aquatic extracts of powdered leaves (1gr to 30ml) were prepared and different concentrations of each extract were used to evaluate the rate of hatching and mortality of J2s. In terms of the effect of extracts on nematode egg hatching, all three plants were had inhibitory effects. High concentrations of the extract was more effective, so that the 50% concentration had the best effect in reducing hatching and the concentration of 25% had also good effect. The effect of extracts on the mortality of J2s was also significant, and all three plants, caused a significant percentage of J2 mortality compared with control, especially at higher concentrations. Of these, the concentration of 25% of all three plants had an appropriate inhibitory effect on J2s death. In another experiment, the effect of these extracts on seed germination of tomato (Super Strain B) was examined. Different concentrations of extracts were placed in sterile petri dishes covered with sterile filter paper and the seeds were placed inside them. The percentage of seed germination was recorded within a week. In general, it can be said that the extract of the plants had no negative effect on the germination of tomato seeds.

In this study, direct application effects of antagonistic bacteria Bacillus subtilis and Salicylic acid on Fusarium growth Fusarium oxysporoum f.sp. lycopersici examined in vitro, in two formats, contrast test and volatile materials test. Effect of different concentrations of salicylic acid (2-8 mM) on Fusarium growth has tested as a manner mixing with medium. In greenhouse tests induction effects was resuled from application of Salicylic acid and Bacillus subtilison on activity of PAL as one of the most important enzymes in plant defense tomato which infected with Fusarium wilt and Meloidogyne javanica also it was investigated when the two diseases interact with each other. According to the results all Salicylic acid concentrations completely prevented growth of the fungui. In contrast tests and volatile, antagonist bacteria significantly controlled Fusarium that respectively was 34.8 and 35 %. Evaluation the activity PAL indicated that all treatments including bacteria and Salicylic acid effectively increased level of enzyme activity compared with control and infected plants with fungi and nematodes and highest enzyme activity was in plant treated with pathogens and B. subtilis and salicylic acid on fifth days after inoculation.

To study the antagonistic effects of two antagonistic fungi, Talaromyces flavus and Trichoderma harzianum in the control of root knot nematode, Meloidogyne javanica in tomato, experiments were carried out in two years (2013-2014). The experiments were conducted and executed with eight treatments and five replications using pots with a completely randomized design under greenhouse conditions. To prepare treatments, 2×107 spores of T. flavus and T.harzianum (originally isolated from tomato roots) per gram soil, were added to the pots containing three kg of pasteurized soil. After transplanting four leaves seedlings of tomato, pots were inoculated with 15000 eggs and juveniles of the nematode per pot. The uninfected control pots contained only pasteurized soil without root knot nematode and antagonistic fungi. Two months after inoculation of the nematode, the growth parameters of the plants including foliar height, root weight, and some nematode- related parameters including the number of galls and egg mass, final population and reproduction factor were measured. In the combined statistical analysis, the differences were observed in data and analysis was performed separately for two years. The results showed that the antagonistic fungi were effective in increasing the plant growth and there was significant decrease of nematode population up to 80% in comparison with the infected control (α=0.05). According to the results, T. harzianum was more effective than T. flavus in increasing plant growth and decreasing the population of the nematode (78 and 67%, respectively), but differences were not significant. Furthermore, the combination of two fungi was more effective than other treatments in increasing plant growth characteristics and controlling the root knot nematode such as reduction of the number of galls and reproduction factor.

Mature seeds of Melia azedarach were harvested from north of Iran، Mazandaran province. The seeds were dried in the shade at room temperature (about 25ºC)، powdered by blender. Extraction from the seeds powder was done in the Soxhlet extractor. Water soluble and Non-water-soluble components of the seed powder extract were separated by dichloromethane/water. In addition، Tween 85 was added to the extract and an 11% formulation was made from the seed extract in the laboratory. The toxicity of formulation to the root-knot nematode، Meloidogyne incognita، was studied in laboratory and pot experiments. Application rates of formulation were 0. 125، 0. 25، 0. 5، 1، 2، 4، 8 and 16 percent for the laboratory experiment in order to determine their effects on motility and mortality of second-stage juveniles (J2) after two different exposure times (24 and 48 h). In pot experiment، 0. 125، 0. 25، 0. 5، 1، 2 and 4 percent of the formulation were applied on nematode activity and plant growth components of tomato (Solanum lycopersicum). Neither J2 immobility nor mortality was observed in treatments with 0. 125 and 0. 25% doses. Exposure time was significantly (p<5%) affected J2 mortality. After 24 h، J2 mortality was 0. 0، 44. 30 and 76 % following treatment with 4، 8 and 16% formulation، respectively، while 100% J2 mortality was recorded for the same concentrations، after 48 h of exposure. In the pot experiment، all of the concentrations significantly reduced the numbers of galls، egg masses and eggs in tomato roots، J2s in soil and tomato roots and overall nematode population. Treatment of 4% of formulation was toxic to tomato plants and significantly reduced tomato root and stem length and fresh weights in comparison to control. Results of the laboratory experiments show good stability of the formulation. In general، 1 and 2% concentrations of the formulation controlled root knot nematode and improved tomato growth parameters under the laboratory conditions as compared with the control. Use of the recommended concentrations of this new formulation، could be a natural and eco friendly way to control root knot nematode and to reduce hazardous effects of chemical pesticides.

Essential oil from aerial parts of Tanacetum polycephalum Schultz Bip. subsp. polycephalum at the rates of 8000, 4000, 2000, 1000, 500, 250, 125, 62.5 and 0 mg l-1was tested for its nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita (Kofoid and White) Chitwood. 100 percent J2 mortality was achieved with essential oils of 8000 and 4000 mg l-1. Nematicidal activities were recorded as 44.4, 22.8 and 6 percentages for concentrations of 2000, 1000 and 500 mg l-1 respectively. No nematode mortality was seen in treatments of 250, 125, and 62.5 mg l-1of the oil. Analysis by Gas Chromatography (GC) and GC-Mass Spectrometry (GC-MS) led to identification of 39 major compounds from T. polycephalum oil. Among the chemical components, the main components were trans-Thujone (74.483%), 1,8-Cineole (3.135%), Terpinene-4-ol (2.316%), Borneol (2.351%), cis-Thujone (1.880%),Camphor (1.832%), trans-Pinocarveol (1.333%), and γ-Terpinene (1.059%).

Antagonism of entomopathogenic nematodes (EPNs) on plant – parasitic nematodes (PPNs) has gained interest over the recent years. Therefore، the efficacy of live and dead infective juveniles of entomopathogenic nematode، Heterorhabditis bacteriophora Poinarwith concentrations of 5، 10، 25، 50 and 100 IJs/ml in 24 well plates was evaluated on egg hatching inhibition and second stage juveniles (J2) mortality of the root knot nematode Meloidogyne javanica Treub in concentrations of 50 eggs، 50 larvae and a combination of 50 eggs and larvae. The experimental design was split plot with six treatments and four replications. The whole experiments were replicated twice. The data recorded after 48، 72، 96 and 120 hours showed that both live and dead entomopathogenic nematodes have significant difference on root knot second stage juveniles (J2) mortality and egg hatching inhibition. The highest mortality was achieved in 100 IJs/ml and after 120 hours and the most inhibition of hatching in concentration of 100 IJs/ml and after 48 hours. Concerning the mixture of 50 eggs and larvae، the results indicated that the effect of live juveniles of H. bacteriophora on second stage juveniles (J2) mortality have no significant difference among the various time treatments.