Potato " Solanum tuberosum " is a dicotyledonous, annual , herbaceous plant which belongs to the family of Solanaceae. It is the most important source of plant nutrition with the annual production of 328 million tones and is cultivated over an area of 19.1 million hectares. It is considered as the fourth major crop after wheat, maize and rice. Potato is propagated asexually through tubers which are the vegetative part of the plant. Potato plants are prone to a number of virus attacks during growing season which produce infected tubers that transmit easily from generation to generation and farm to farm by means of physical and biological carriers. " Solanum tuberosum . Istanbuli" is a genotype with good marketing in Iran but due to severe virus infection and consequently decline in yield per unit area, its cultivation is limited to few provinces for local consumption. The most important potato viruses are (PLRV) Potato leaf roll virus, (PVY) Potato virus Y, (PVX) Potato virus X and … . Their symptoms include mosaic, leaf roll, necrose of leaves and general weakness of plant. Using of virus-free seeds and virus-resistant cultivars is the easiest and most economical way to control potato viruses. Meristem culture, Thermotherapy, Chemotherapy and combination of them are the usual methods to eradicate viruses. The objectives of this investigation was to study the effects of plant growth regulators on ’ Solanum tuberosum. Istanbulli’,optimizing it's tissue culture media, effect of chemotherapy on " Solanum tuberosum. Istanbuli " and meristem culture combined with thermotherapy to eradicate viruses. The experiment of studying the effect of plant growth regulators was carried out using IAA (0, 0.5,2.5 and 5 mg / L) and BAP ( 0, 1.5, 3, 4.5 mg / L ),arranged in 16 treatments in a factorial experiment in a completely randomized design with three replications. The maximum length of shoot was observed in the treatment of IAA (5 mg / L) and BAP ( 0 mg/L ). The maximum number of shoots was observed in the treatment of IAA ( 0.5 mg/L) and BAP ( 3 mg/L). The minimum number of shoots was observed in the treatment BAP ( 0 mg/L ) and all concentrations of IAA. Chemotherapy using ribovirin in 10, 20, 30, 40 mg/L was not successful to eradicate viruses PLRV and PVY in " Solanum tuberosum. Istanbuli " . Removal of 0.2 mm meristems from infected plants which have been heat treated in 35-37 C for five weeks lead to eradicate PLRV, PVX and PVY from plants and virus-free plants produced. Key words Solanum tuberosum' Istanbuli ' , Plant growth regulators, Meristem culture, Thermotherapy, Chemotherapy
