Abstract: The physiological changes in the ultra-low luminescent intensity, the activity of peroxidase, isoenzyme and cytochrome oxidase,and the carbon-nitrogen metabolism in the sprouting period as weel their subsequent effects on plant-growth and tuberization were studied in virus-infested and virus-free potato seed tubers, The results indicated that there were significant or very significant differences in physiological ndices between virus-infested and virus-free seed tubers, thus demonstrating a possibility of an early physiological diagnosis and selection of quality seed tubers.

Key words: Potato seed tubers , Virus-infestedf , Physiological diagnosis