Polyploid Initiation in Hawaii Tree Species

In Hawaii, many plant species commonly used by landscapers yield abundant large fruits that can injure people/property, attract rats and other pests, create an unsightly appearance and potentially become invasive. Sterile forms of these landscaping plants would eliminate their high-maintenance and invasive characteristics. Polyploid forms of plants, particularly triploids, are often sterile. Autotetraploids also frequently display some degree of sterility. In addition, polyploids typically exhibit unique physical characteristics such as thicker leaves, larger organs, and higher levels of chemical compounds. A project was initiated to create tetraploid forms of eight commonly utilized species of trees: Thespesia populnea, Calophyllum inophyllum, Clusia rosea, Schefflera actinophylla, Heritiera littoralis, Jatropha curcas, Plumeria Stenopetala, and Erythrina sandwicensis. Various concentrations of the dinitroaniline herbicide, Oryzalin (ranging from 0.01% to 0.5%) were applied to seedling meristems in vivo. Following a period of vegetative growth, the seedlings were tested for higher ploidy levels. Multiple autotetraploids and mixoploids have been identified using guard cell measurements and flow cytometry.