The influence of ten initial population levels (0, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8 and 25.6 second stage juveniles/cm3 soil) of Meloidogyne incognita and M. javanica on olive cultivar Zard growth was studied in two pot trials. Ten month old self-rooted olive cuttings were individually transplanted into 2 000 cm3 pot and inoculated with the defined initial populations, of both nematode species. Plants were grown in glasshouse for 13 months, then they were uprooted and plant growth (percent growth increase of main shoot length, number of nodes on main shoot, top and root fresh and dry weights and root length) and nematode parameters (root gall index, J2/g root, final nematode population density and reproduction rate Pf/Pi) were recorded. Results showed that cv. Zard was more susceptible to M. javanica than to M. incognita. A significant reduction of main shoot length growth 37.6 % and 10.7 % was observed at 0.1 and 12.8 juveniles/cm3 soil of M. javanica and M. incognita, respectively, in comparison to uninfested plants. Root systems of olive plants grown in M. incognita or M. javanica infested soils were galled within the gall index range 1.4–6. No significant differences were observed in the number of nodes on main shoot, top and root fresh weights and root dry weight at high levels of M. incognita Pi. A tolerance limit (T) of 0.4 juveniles/cm3 soil was estimated for olive plants cv. Zard to M. javania. The use of resistant olive rootstock or selected cultivars is recommended to minimize or to limit damage of nematode infections in nurseries and to prevent secondary attacks of soil borne plant pathogens especially Verticillium dahliae.

The southern root-knot nematode (SRKN; Meloidogyne incognita) is one of the main pathogens for tobacco. The objectives of this study were to determine the genetic parameters and heritability of SRKN resistance in air-cured tobacco. For this purpose three resistant parents (Urmia3, KY9, K17) and two susceptible parents (Ergo, Burley TMV4) were crossed based on half diallel and analyzed by Hayman's method for reaction to Meloidogyne incognita. Fifteen genotypes (parents and hybrids) were planted in the greenhouse in a completely randomized design with five replications and inoculated with 2500 J2 M. incognita race 2 one week after transplanting. Investigation of gall index (GI), number of egg masses (NEM) and average number of eggs per mass (AEM) showed significant differences among genotypes. Non-additive effects in AEM and additive effects in GI and NEM played an important role. Narrow-sense heritability was estimated as 0.75, 0.56 and 0.28 for GI, NEM and AEM, respectively, which revealed that AEM is not a suitable trait for nematode resistance identification. Regression analysis indicated that KY9 is an appropriate donor parent for SRKN resistance. Resistance to M. incognita race 2 is conditioned by a single partially dominant gene.

Background Essential oils from aerial parts of Achillea wilhelmsii, Tanacetum polycephalum and Teucrium polium were isolated by using Clevenger-type apparatus and tested at different concentrations for their nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita in vitro condition. The chemical components of the essential oils and seed extracts of each plant (0.2 g) were extracted with maceration with methanol/acetic acid mixture (85:15, v/v). Analysis was done by Gas Chromatography, GC-Mass Spectrometry) and HPLC. Identified chemical components were tested after this on J2 of M. incognitain. Nuclear magnetic resonance spectroscopy was done to investigate the properties of organic molecules by drawing their spectrum using Broker AVANCE AQS-300 MHz. Results Significant difference was achieved on nematicidal activity of essential oils based on the plant species and oil concentrations. GC and GC–MS led to identification of 41, 39 and 45 major compounds from T. polium, T. polycephalum and A. wilhelmsii oils, respectively. A number of 10 components with different ranges of percentage were recorded in all of the tested plants oils. Use of HPLC resulted in identification of 4, 3 and 2 chemical compounds in the extracts of A. wilhelmsii, T. polycephalum and T. polium, respectively. The nematicidal activity of commercial polyphenols at the concentration of 1100 ppm showed 58.3, 48.9, 28.2 and 26.8 percentages J2 mortalities by catechin, coumarin, gallic acid and chlorogenic, respectively. Nematotoxicity test of commercial terpenoids showed the highest J2 mortalities (more than 80%), in concentrations of 100 and 200 ppm limonene, β-pinene and α-pinene. However, it was less than 30% of J2 mortality caused by terpinen-4-ol, α-terpineol and linalool. Conclusions Compounds such as Limonene, β-pinene and α-pinene were detected in all of the tested plants, A. wilhelmsii, T. polycephalum and T. polium, having an effective nematicidal action versus terpinen-4-ol, α-terpineol and linalool.