کارایی برخی ترکیبات القا کننده مقاومت در گوجه‏ فرنگی نسبت به Fusarium oxysporum f. sp. lycopersici در شرایط آزمایشگاهی و گلخانه‌ای

Fusarium wilt is considered as one of the most important diseases of tomato and application of disease resistance activators in susceptible or moderately susceptible cultivars is an environmental friendly method in disease control. In current study, first the effect of salicylic acid, methyl salicylate and oxalic acid in inhibition of mycelial radial growth was evaluated in laboratory conditions using a completely randomized design and then, possibility of induction of systemic acquired resistance in tomato plants by application of these materials was assessed in glasshouse conditions. This research was conducted in a factorial experiment in the base of completely randomized design. Plants treated by leaf spray and soil drench methods and then inoculated with spore suspension of fungus. Disease severity, wet and dry weight of shoots and roots and plant height were measured. In laboratory studies, oxalic acid in the concentrations of 2000, 1000 and 500 ppm showed the highest effect on mycelial growth inhibition with 80, 65 and 31% respectively. Although various concentrations of salicylic acid and methyl salicylate showed significant difference in inhibition of mycelial growth in compare with control treatment but their direct effect on pathogen was evaluated in the range of 7.41 to 22.2%. In glasshouse experiments, there were significant difference only among the types of inducers in disease severity and plant growth properties but there was no significant difference between two concentrations of inducers. All inducers increased plant growth characteristics like wet and dry weight of shoots and roots and plant height significantly. Only effect of abscisic acid on wet and dry weight of roots and plant height was similar to control plants and no significant difference was observed. Methyl salicylate in concentrations of 100 and 200 µM and salicylic acid in concentrations of 0.5 and 1 mM, respectively with 88.9, 77.8, 77.8 and 72.2 % decrease in disease severity, showed the highest effect on disease control in glasshouse conditions in leaf spray method which was significant in compare with control plants. Abscisic acid 100 µM had the least effect (11.1%) among resistance inducers. Through root application of inducers, both methyl salicylate 100 µM and salicylic acid 0.5 mM with 77.8 % reduction and abscisic acid 100 µM with 27.8 % reduction in disease severity, showed the highest and lowest effect on disease control respectively. In both methods of application of inducers, oxalic acid with 38.9 to 61.1% decrease in disease severity had the intermediate effect on Fusarium wilt control.