JWSS - Journal of Water and Soil Science

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Solarization of field soil through mulching with transparent polyethylene sheets alone and in integration with farm yard manure (40 T/ha) and/or metalayl (25 kg/ha) during summer 1994-95 for five weeks in Isfahan resulted in an increase in temperature of 10 °C (± 1) and moisture preservation of up to 82%. Solarization effectively reduced foot-rot of cucumber (Phytophthora drechsleri) in the above treatments up to 88%, 96% and 95%, respectively.

Solarization, farm yard manure and their integration reduced the infection of Meloidogyne javanica up to 50%, 57% and 83% while plant parasitic nematodes were also reduced to 72%, 75% and 86%, respectively. The populations of free living nematodes increased only in farm yard manure and in integration with solarization by 30% and 53%, respectively.

Solarization effectively reduced the populations of almost all weeds by around 100%, except for Cyperus rotundus and Sonchus asper which were reduced by 59% and 44%, respectively.

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This research was conducted to study the effect of nematode (Meloidogyne javanica) on severity of tomato Fusarium wilt (Fusarium oxysporum f.sp. lycopersici race 1) and changes in Phenylalanine ammonia lyase (PAL) activity in split-root assays to show the possibility of systemic induced susceptibility caused by nematode to the fungus by local nematode infection. The results showed that the activity of nematode in one part of root confered susceptibility to Fusarium wilt in other part of the plant root and subsequently disease symptoms increased significantly in comparison to the control (without nematode inoculation). PAL specific activity showed a significant decrease in one half of split-root inoculated with fungus when the other half was inoculated with nematode as compared with the control (without nematode inoculation). Based on the results obtained in this study, nematode infection in one part of tomato plant root resulted in suppression of tomato defenses in all parts of the root, reduced tolerance or resistance to the fungus (as secondary pathogen) and intensified the fungal disease.