Abstract
Potato microtubers (MT), generally 1 gram in fresh weight, are mass-produced under in-vitro conditions, and they are used as seed tubers in the field. However, less is known about the varietal differences in tuber yield in the plants cultivated in the field using MT as seed tubers. The purpose of this study is to elucidate the differences in tuber yield characters of plants grown from MT among 28 varieties and breeding parents used in Japan. On average, the number of tubers, individual tuber weight and tuber fresh yield of plants grown from MT were 90%, 80% and 70%, respectively, of those in the plants grown from conventional seed tubers (CT, generally about 50 gram). The varietal differences in tuber numbers and individual tuber weight were greater in MT plants than in CT plants. In addition, there were significant interactions between seed tuber types and varieties in tuber numbers and individual tuber weight, but not in tuber yield. This is because there was a high negative correlation between the MT/CT ratios in tuber numbers and individual tuber weight. The varieties were divided into two groups; one with a larger number of tubers and lighter individual tuber weight in MT plants than in CT plants, and the other with opposite characters. These results indicate that varietal differences in the response of tuber yield to the use of MT must be taken into consideration for the use of MT as seed tubers.
