Production of hybrid plants by crossings between triploid and diploid Japanese butterbur [Petasites japonicus] cultivars and their characteristics

Crossings between triploid and diploid in cultivated Japanese butterbur (Petasites japonicus Fr. Schmidt) were made and the agronomic traits of hybrid plants for harvesting petioles were investigated. As a result hybrid plants from the crosses of 'Aichiwasebuki' (triploid) x 'Mizubuki' (diploid, native cultivar of Gunma pref.), 'Mizubnki' (triploid, native cultivar of Tokushima pref.) x 'Mizubuki' (Gunma) and 'Kibiji' (triploid) x 'Mizubuki' (Gunma) were obtained. Some hybrid plants from 'Aichiwasebuki' x 'Mizubuki' (Gunma) grew more vigorously than their parents. Among hybrid plants, there were several hybrids that did not develop anthocyanin pigments at petioles. By flow cytometry, the hybrid plant 'AM-35' was estimated as diploid, and 'AM-1' and 'AM-51' as aneuploid.'AM-1' showed early maturing, high petiole yield, and less anthocyanin pigments at the petioles compared with 'Aichiwasebuki'. Therefore, there is a possibility of selecting a new cultivar for harvesting petioles from hybrid plants of 'Aichiwasebuki' (triploid) and 'Mizubuki' (diploid, Gunma).