Abstract
The horticultural and breeding performances of some A. thunbergii G. Don and A. chinense G. Don clones, their hybrids and backcross progenies, and their pollen compatibility with A. tuberosum Rottl. ex Spreng. 'Tender-Pole' were evaluated. The A. chinese × A. thunbergii hybrids showed outstanding adaptation to Kagoshima conditions. They produced purple colored globular inflorescences from late October to November. However, except for A. tuberosum 'Tender-Pole', the entries produced thin and weak flower scapes, which disqualified them for immediate use as cut flowers. A hexaploid progency of A. chinense × A. thunbergii, 87C28, produced the strongest flower scape. Data on percent emergence and vigor underline the superiority of the A. chinense × A. thunbergii hybrids in comparison with clones of the parental species.
Results from an incomplete diallel cross indicate a) the cross combinations which may benefit from embryo rescue for better survival and b) unproductive parental materials. Comparison of progeny vigor 7 months after germination revealed several parents which produced superior hybrid progenies relative to the corresponding selfed ones. Of the eleven pairs of reciprocal hybrids, seven showed clear differences in vigor. A putative hybrid seedling from a 87C28 (A. chinense × A. thunbergii) × A. tuberosum 'Tender-Pole' cross is now being grown to verify its hybridity.
