Inducing host plant-based systemic resistance is one of the modes of action involved in tri-trophic interactions between host plants, pests and mutualistic microorganisms. Two different types of systemic resistance – systemic acquired resistance (SAR) and induced systemic resistance (ISR) – were found to be functional against pathogens and plant-parasitic nematodes. In this study, the ability of Trichoderma harzianum isolate T10 and insecticidal active neem powder (NP) to induce systemic resistance in tomato against the root-knot nematode Meloidogyne javanica was compared with salicylic acid (SA) and jasmonic acid (JA) as standard elicitors for SAR and ISR, respectively. Results showed that, when the biotic and abiotic elicitors were applied to the inducer side of a split root plant system, a significant reduction in nematode infection was observed on the responder side. Physiological changes in the tomato plant due to the induction of SAR or ISA by these biotic and abiotic elicitors were further investigated using HPLC. Results demonstrated that T10 significantly increased the accumulation of different metabolites in the shoot of the tomato over the NP, JA and SA elicitors. Furthermore, the results demonstrated that several metabolic, physical and biochemical changes occurred in the shoots of the treated plants with both the biotic and abiotic elicitors. The percentage of membrane leakage (Ml) at nematode-infected tomato roots was significantly high, but the differences in percentage leakage were not significant in other treatments compared to the non-infested control. The best results were recorded with SA, T10 and NP, which gave the lowest MI% compared to the infested plants.
Globally, root-knot nematodes (RKN) recorded as destructive plant pathogen with a wide host range. A field survey of RKN Meloidogyne spp. associated with different vegetable and fruit crops and weeds in sandy and clay soil was carried out in Beheira and Menoufia governorates in Egypt. A total of 81 plant and soil samples were collected and examined. Nematodes extracted from soil samples under laboratory conditions and identified then frequency of occurrence (F.O.%) and population density (P.D) were calculated. A survey in the selected locations showed remarkable frequency of occurrence and population density of RKN in many vegetable crops and weeds. Results showed that the population density and frequency of occurrence of RKN Meloidogyne spp. were greatly differed in the different crops and different locations. Results showed that frequency of occurrence of Meloidogyne spp. was 100 % in Kom Hamada, Beheira governorate, wheras the population densities recorded between 154-692 J2 / 250 g soil. Results indicated that Meloidogyne spp. recorded infecting different weeds such as:Common lambsquarters (Chenopodium murale L.), Small bindweed (Convolvulus arvensis), Common purslane (Portulaca oleracea L.) and Solanum (Solanum nigrum). The frequency of occurrence of root-knot nematodes Meloidogyne spp. showed different values in the surveyed locations.
Root-knot nematodes (RKN) became a true limited factor for eggplant production worldwide.Experiments were designed to evaluate the effectiveness of different compost types on RKN management in Eggplant under greenhouse conditions. Different compost types i.e. plant, animal, rice straw and maize wood compost at different doses 10, 20, 30, 50 and 100g/ pot were used. Results indicated that all evaluated treatments showed a great potential in decrease all related nematode parameters i.e. number of galls, egg masses, females/root system and second stage juveniles(J2s)/250g soil compared with control. The most effective treatment in reducing all nematode parameters was animal compost. Results illustrated that all compost types markedly increased eggplant growth parameters. The highest plant growth parameters enhancement obtained when plants treated with animal compost at 10g/ pot, followed by maize wood compost at the same rate of 10g/ pot. The lowest plant enhancement recorded with rice straw compost at 100g/ pot.
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