Breeding and Selection of Leucospermum Hybrids for Tropical Climates

One objective of the protea research program at the University of Hawaii is to help the Hawaii floriculture industry expand with selected protea varieties that can be grown on low elevation lands formerly cultivated in sugar or pineapple, or on low elevation lava fields on the Island of Hawaii, since these lands are more available and less expensive than the upper elevation lands where protea has traditionally been grown. Leucospermum (pincushion) hybrids were evaluated for growth and flowering characteristics at Kunia, a warm, 76-m elevation site on the Island of Oahu, and compared with the performance of the same cultivars grown at Kula, a cool, 920-m elevation site on Maui, and a location of concentrated protea production in Hawaii. The mean temperature of 23.0?C at Kunia is 5.3?C warmer than at Kula, the mean maximum temperature of 28.0?C at Kunia is 5.7?C warmer than at Kula, and the mean minimum temperature of 18.0?C at Kunia is 4.8?C warmer than at Kula. Twenty-nine hybrids were grown at both the Kunia and Kula locations. A few hybrids were simple primary crosses, while others were complex hybrids with 4 to 9 species in their genealogy, sometimes representing 4 taxonomic sections. Data linking the composition of taxonomic sections in the genealogy of hybrids with their ability to flower at warm temperatures show that Leucospermum species in the section Cardinistylus appear to contribute some warm temperature flowering ability to their hybrids.