GLYCOALKALOID ACCUMULATION DURING TUBER DEVELOPMENT OF EARLY POTATO CULTIVARS

Plants of early potato cultivars were sampled at successive harvests d uring tuber development and individual tubers were analysed for a-sola nine and alpha-chaconine using high-performance liquid chromatography. Mean tuber total glycoalkaloid concentration (alpha-solanine plus alp ha-chaconine) per plant decreased with time and statistically signific ant differences between cultivars were observed in the patterns of dec line during tuber growth. The mean tuber ratio of a-chaconine to cr-so lanine increased during tuber development and was also affected by gen otype. Total glycoalkaloid concentration for individual tubers of mark etable sizes (up to 50 g fresh weight) exceeded the safety limit of 20 mg per 100 g fresh weight for cultivars Home Guard and British Queen but not for Rocket. These differences were attributable to differences in both rates and patterns of glycoalkaloid accumulation during tuber development, although in all cultivars results were consistent with g lycoalkaloid accumulation occurring in the expanding peripheral cell l ayers of tubers for a considerable period after tuber initiation.