Table 1. Frequency of shoot regeneration on four potato cultivars.

	Medium-I		Medium-II
Sayaka	40/60	(66.7%)	42/60	(70.0%)
Konafubuki	28/60	(46.7%)	53/80	(66.3%)*
Sakurafubuki	3/58	(5.2%)	9/58	(15.5%)*
Norin-1	2/60	(3.3%)	2/60	(3.3%)

The sections of potato stems were placed in dishes with Medium-I and Medium-II. Plants were cultured for 30 days, and regenerated shoots were counted. The values indicate the total number of sections of potato stems that regenerated shoots in the stems examined. Values in parentheses show the regeneration ratio. Asterisks indicate the statistical significance between regeneration frequencies in the experiments on Medium-I and Medium-II, which was determined using a proportion test (p<0.1).