Seed dormancy and germination of a panel of New Zealand plant species : Carex trifida, Corposma robusta, Cyperus ustulatus, Hebe stricta, Muehlenbeckia australis, Myrsine australis, Phormium tenax and Sophora prostrata : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University
Literature was reviewed on the germination and possible uses for revegetation of the New Zealand indigenous species selected. Seeds of Carex trifida, Coprosma robusta, Cyperus ustulatus, Hebe stricta, Leptospermum scoparium, Muehlenbeckia australis, Myrsine australis, Phormium tenax, Phormium 'Yellow Wave' and Sophora prostrata were assessed for germination rates, percentage germination, dormancy and the effects that temperature has on germination. Seeds of Carex, Cyperus and Myrsine showed no germination in light or dark at 20°C. In contrast, 12 weeks of low temperature stratification resulted in a high percentage of seed germinating for Carex and Cyperus. There was no germination of Myrsine despite high viability in the initial germination experiment and the stratification experiment. Removal of the endocarp and a period of stratification increased germination percentage of Myrsine to 91%. Germination was low for Muehlenbeckia in the light at 20°C, but 4 weeks of low temperature stratification increased germination rate. After 2 years, 80% of Coprosma seeds germinated but germination rate increased after subjecting the seed to 8 weeks or more of stratification. No seeds of Coprosma or Muehlenbeckia germinated in the dark. Rapid germination of Hebe seeds was obtained, with 100% of the seed germinating in the light while only 7% germinated in the dark. Leptospermum had rapid germination, with 100% germinating in the light, while only 3% germinated in the dark. A low percentage of Phormium seed germinated in both the light and dark in the first month and no further germination was observed. In contrast, 8 weeks or more of low temperature stratification resulted in almost complete germination. There was rapid germination of Sophora seeds with 100% of the seed germinating in the light and dark. Carex seed had a limited temperature range at which it germinated (22°C to 26°C), while Cyperus had a wider range (18°C to 32°C) but did not germinate at low temperatures (6°C to 14°C). The optimum germination range for Cyperus was 24°C to 30°C. Hebe did not germinate at high temperatures (30°C to 32°C) but successfully germinated at all other temperatures with the optimum germination range being 6°C to 24°C. Leptospermum did not germinate at 6°C but had maximum germination at most other temperatures. Muehlenbeckia and Phormium germinated at all temperatures tested (6°C to 32°C) with the most seed germinating at 20°C for Muehlenbeckia and between 14°C to 22°C for Phormium. Sophora did not germinate at the low temperatures (6°C to 10°C). The germination rate increased with temperature for Cyperus, Hebe, Leptospermum, Muehlenbeckia, and Phormium. Generally, for Carex and Sophora as temperature increased germination rate slowed. It appeared that light is required for Hebe and Leptospermum to germinate. Sophora required scarification but not light. Coprosma and Muehlenbeckia required light and a period of chilling to increase the rate of germination. A small percentage of the Phormium population is not dormant but a period of chilling increased the germination percentage for that portion of the population that is dormant. Carex and Cyperus required a period of chilling in order to break dormancy. Myrsine required removal of endocarp and a period of chilling to germinate. A list of cleaning descriptions and the equipment that was used for each species studied is reported. Preliminary results of a hydroseeding trail using the species studied were also reported.