بررسی روش‌های مختلف سالم‌سازی در بذرهای گوجه‌فرنگی آلوده به باکتری Clavibacter michiganensis subsp. michiganensis

Tomato plant is host of some prokaryotic pathogens. Tomato bacterial canker caused by the Germ-positive bacterium Clavibacter michiganensis subsp. michiganensis. For the first time in Iran, the pathogen was reported from tomato fields around Urmia in 1988. Symptoms of the disease are including wilting, leaf necrosis, creamy to yellow lines along the stems and petioles that they become gradually brown, cracked and turned into cankers. Fruits may show light brown spots with white halo is called “bird’s eye”. The pathogen is seed-borne and this character can be one of the reasons for disease rapid spread. Contaminated seeds usually give rise to apparently healthy seedlings, symptoms only appearing as plants approach maturity. In this study, the effect of different heat treatments, bactericide compounds and antibiotics was evaluated on the seed disinfestation. Heat treatments include temperatures of 45-65 °C at 15, 25 and 35 minutes. In bactericides treatments, recommended doses of Mancozeb (2/1000), Bordo (1/1000), Nordox (2.5/1000) and copper oxychloride (3/1000) were used. In addition, the effect of nine antibiotics was investigated on seed disinfestation. Treated seeds stored at 25 °C on nutrient agar (NA). Petri dishes were examined for bacterial growth up to 5 days. In all treatments, the seed viability percentage was considered compared to the untreated control. The experiments were designed in a completely randomized design with four replications. In each replicate 40 seeds were used. According to the results, the treatment of 60 °C for 25 minutes showed the best heat treatment result. This treatment reduced 95% seed infestation, and 97% of treated seed maintained their viability. The treatment of 65 °C for different times, showed the most disinfestation effects but the treated seeds could not germinate. Mancozeb and copper oxychloride reduced 98.08 and 92.46% of seed infestation and Bordo and Nordox decreased 76.48 and 53.07% of infestation, respectively. Among studied antibiotics, gentamicin, doxycycline, furazolidone, nalidixic acid and rifampin with 100% infestation reduction were the most effective antibiotics. After those, streptomycin, cloxacillin, cefalexin and erythromycin were placed with 64, 60, 52 and 44% seed disinfestations, respectively. There was a significant difference at 1% level between treatments. Regarding to mentioned bacterial disease is seed borne, seed disinfestation before planting can be an effective step in reducing the disease, and it should be considered as one of the effective ways in integrated disease management.