The Menispermaceae comprise several genera of climbers and, rarely, trees and shrubs. Whilst several species are cultivated for ornament, one species (Dioscoreophyllum cumminsii Diels, serendipity berry) provides a powerful proteinaceous sweetener. The fruits are drupes or drupe-like and seed storage behaviour is probably orthodox. The information on seed dormancy and germination provided here is limited to the genus Dioscoreophyllum.
DIOSCOREOPHYLLUM
|
D. cumminsii Diels |
serendipity berry |
I. Evidence of dormancy
Seeds of D. cumminsii can show considerable dormancy (1-3). There can be a delay of 6 months before sown seeds germinate and emerge (2).
II. Germination regimes for non-dormant seeds
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III. Unsuccessful dormancy-breaking treatments
Light: sunlight (1,2)
Pre-soak: 1h (1,2); 55°-60°C; 10 min (1,2)
Potassium nitrate: pre-applied, 24h, 0.25% (3)
Scarification: sulphuric acid, 0.05, 0.1, 0.2 N, 1h (1,2); concentrated sulphuric acid, 3 min (3); concentrated sulphuric acid, 3 min, then pre-chill, 5°C, 14d (3); acetic acid, 0.05, 0.1, 0.2 N, 1h (1,2)
IV. Partly-successful dormancy-breaking treatments
Pre-soak: 24h (3)
Potassium permanganate: pre-applied, 24h, 0.5% (3)
Indoleacetic acid: pre-applied, 24h, 250-1500 ppm (3)
Naphthalene acetic acid: pre-applied, 24h, 250-1500 ppm (3)
GA3: pre-applied, 24h, 1000-2000 ppm (3); pre-applied, 24h, 0.01-0.1% (2); pre-applied, 2h, 0.05, 0.1% (1,2)
V. Successful dormancy-breaking treatments
Light: dark, at 23°-26°C (1,2)
GA3: pre-applied, 2h, 0.5% (1,2); pre-applied, 24h, 500 ppm (3)
VI. Comment
Light, or at least direct sunlight, inhibits the germination of seeds of D. cumminsii (1,2). Pre-treatment with gibberellins can, however, promote full germination in light (1-3), but the response depends upon the concentration applied and the duration of pre-treatment. On the basis of the evidence available at present it is suggested that the seeds be tested for germination at 25°C in dark after a 24 hour pre-treatment with 500 ppm GA3 (3) or a 2 hour pre-treatment with 5000 ppm GA3 (1,2). However, it should be noted that there are some contradictions in the literature concerning suitable promotory pre-treatments. Consequently the above pre-treatments may require modification. Note also that even where GA3 has been applied there may be a considerable delay before the seeds begin to germinate. For example, in one investigation no germination was observed until 68 days after the test had commenced (3). Consequently a germination test duration of 90 days, or more, may be required.
VII. References
1. Adansi, M.A. and Holloway, H.L.O. (1977). Seed germination and establishment of the serendipity berry (D. cumminsii Diels). Acta Horticulturae, 53, 407-411.
2. Holloway, H.L.O. (1977). Seed propagation of Dioscoreophyllum cumminsii, source of an intense natural sweetener. Economic Botany, 31, 47-50.
3. Uzo, J.O. (1983). Studies on the nature of seed dormancy of the serendipity berry Dioscoreophyllum cumminsii Diels. Acta Horticulturae, 123, 197-205.
