M. J. Arvin - Department of Horticulture, College of Agriculture, Shahid Bahonar University, Kerman, Islamic Republic of Iran.
D. J. Donnelly - Department of Plant Science, Macdonald Campus of McGill University, ۲۱,۱۱۱ Lakeshore Road, Ste. Anne de Bellevue, Quebec, H۹G ۳ V۹, Canada.

Ten Solanum tuberosum cultivars and accessions from ۱۱ wild Solanum species were evaluated for their tolerance to salt (۲۰۰ mM NaCl or ۱۰۰ mM Na۲SO۴), drought (۳۵% PEG), cold (-۴ºC) and heat (۳۷ºC). Evaluation was based on electrolyte leakage from de-tached leaves of in vitro plantlets. Testing involved a rinsing treatment with three changes of distilled water to remove electrolytes from leaf and petiole surfaces, an exposure period of ۲۴ hours for salt and PEG stress and four hours for temperature stress and a rehydra-tion period of ۲۴ hours in distilled water followed by measurement of electrical conductiv-ity into distilled water to determine the effects of stress. Significant differences were ob-served between Solanum genotypes for all types of stresses. Among the S. tuberosum culti-vars, stress tolerance was great to NaCl and PEG in Alpha and Bintje; to Na۲SO۴ in Agria and to heat and cold in Norland. Among the wild species, tolerance to all stresses was great in S. demissum, to all stresses except heat in S. acaule and to heat and cold in S. commersonii. The correlations among types of stress tolerance were significant for all stresses except for heat and drought. The level of tolerance in some wild species was sig-nificantly greater compared with the cultivars tested. There appears to be a wide genetic base available to improve the stress tolerance of cultivated potato.

Abiotic stresses, Electrolyte leakage, Potato