The total carotenoid content was determined of tubers from 38 Solanum phureja lines grown in field plots over 3 years. The results indicated a significant difference between years, but the ranking was similar from year to year and the interaction between season and variety was small. Postharvest storage significantly reduced the carotenoid content of the tubers, and reducing the storage temperature further lowered the carotenoid content. Examination of the individual carotenoids revealed that lutein was the most stable and least likely to be reduced, while the levels of the carotenoids derived from beta-carotene were significantly reduced during storage at either temperature. Exposure of the tubers to either mercury or sodium lights resulted in a significant increase in total carotenoid content, concomitant with elevated chlorophyll. Although both types of radiation produced a broadly similar increase in total carotenoid contents, differential effects on the individual carotenoid profile of the light-induced carotenoids were observed.