Macadamia domestication in Hawai'i

摘要

Macadamia is one of the few international food crops domesticated from the Australian flora. It was first described in Australia in 1857, but developed as a crop in Hawai'i following the First World War. Hawai'ian cultivars are responsible for the majority of the world production. This study reviews literature and archival documents to clarify the domestication pathway of this germplasm. Uncertainty about the accepted wild origin of the Jordan introduction, believed to be the main source of Hawai'ian cultivars, is highlighted. An unrecognised additional early introduction of M. integrifolia is identified, but its relevance to commercial germplasm is unknown. The Hawai'ian industry preference for M. integrifolia germplasm may have arisen because the kernels used to evaluate this species were sourced from poorly managed orchards. There is strong evidence that M. ternifolia, which produces bitter kernels, was also introduced at some stage. The advent of vegetative propagation was a major event supporting domestication. The origins of all named cultivars have been clarified and the similarity of two, Keaau and Mauka, has been highlighted. The pedigree of advanced generation selections is clarified indicating Keauhou was a common maternal parent. These results add to the heritage of the plant in both Australia and Hawai'i. In addition, knowledge of the pedigree of advanced selections can be used to improve prediction accuracy in analysis of breeding trials. Finally, improved knowledge of the domestication pathway will assist ongoing conservation and genetic improvement of the genus.