Why are the seeds of this species difficult? The seeds have an uncertain storage behaviour. They may lose viability through drying and cooling. The seeds may also have physiological dormancy, which can be overcome by mimicking the seasonal patterns of the species' native habitat.
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This species has been classified as having Uncertain storage behaviour. Some researchers have been able to partially dry seeds and store them at 5°C, without a loss in viability over two years. Moist storage at 12°C has also helped to maintain viability. Others researchers however have noted viability loss after one year's storage at room temperature.
This species has oily seeds which will absorb relatively less water than similarly-sized non-oily seeds. Be aware that when these seeds are dried to the recommended 15% relative humidity, the equilibrium moisture content will be lower than for non-oily seeds.
The seeds of this species may be Physiologically Dormant (based on members of the same family). If germination is low, overcome dormancy by mimicking the seasonal patterns of the species' native habitat. Use a moist pre-chill or pre-heat treatment (depending on local climatic conditions) or a dry after-ripening treatment, before germinating the seeds on agar, germination paper or sand at their optimum temperature. If this does not work, you can perform delicate surgery to enable the embryo to grow. Excise the tissue near the root tip.
The fruit is dehiscent and splits along a single suture in the husk. The seed coat is made up of thick-walled stone cells and extended fibres. These form the rigid shell enclosing the embryo and cotyledons.
See images of this species at the Digital Atlas of Economic Plants.
Accepted name: Macadamia integrifolia Maiden & Betche
Synonyms: Macadamia ternifolia var. integrifolia (Maiden & Betche) Maiden & Betche
Common name: macadamia nut
References and Links
- Janick, J. and Paull, R.E. (eds) (2008). The Encyclopedia of Fruit and Nuts. CAB International, UK.
- Purseglove, J.W. (1968). Tropical Crops: dicotyledons. Longman Group Ltd., UK.
- AFPD (African Flowering Plants Database) - Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland, and South African National Biodiversity Institute, Pretoria, RSA: Macadamia integrifolia.
- SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Macadamia integrifolia.
- Tropicos - Missouri Botanical Garden, USA: Macadamia integrifolia.