Interspecific hybridization of autumn-flowering Allium species with ornamental Alliums and the characteristics of the hybrid plants

Abstract

Allium species were hybridized interspecifically using the ovary culture method. Autumn-flowering species A. chinense, A. thunbergii and A. virgunculae var. kiiense from the subgenus Rhizirideum were used as female parents. As male parents A. giganteum, A. schubertii and ‘Mount Everest’ from the subgenus Melanocrommyum, A. moly and A. unifolium from the subgenus Amerallium, A. caeruleum from the subgenus Allium and A. nutans from the subgenus Rhizirideum were used. All male parental plants blooming in early summer pollinated the maternal plants after long-term cold storage of their pollen. Consequently, interspecific hybrids of A. chinense×A. giganteum , A. chinense×A. schubertii , A. thunbergii×A. caeruleum , A. thunbergii×A. nutans , A. virgunculae var. kiiense×A. caeruleum and A. virgunculae var. kiiense×A. nutans were obtained. In the cross combinations, hybridization of Rhizirideum species with species from the same subgenus Rhizirideum was more successful than with species from the subgenera Allium and Melanocrommyum, and was unsuccessful with species from the subgenus Amerallium. These results suggest Rhizirideum is distantly related to Amerallium. The success of producing interspecific hybrids between species of different subgenera makes possible the improvement of Alliums by widespread crossing. The morphological characteristics of all hybrid plants were investigated, but only A. chinense×A. giganteum was so weak that we could not leave it alive in the field. Most morphological characteristics of the hybrid plants were intermediate between their parental plants. However, some characteristics represented hybrid vigor. Flowering time of the hybrid plants was intermediate between their parents. However, it was close to the flowering time of the male parents except for A. chinense×A. schubertii . Some hybrid plants had useful traits that included longer and stronger stems and larger flowers than the parental plants and a different flowering time from existing commercial varieties.