The Bromeliaceae comprise about 1500 species of herbaceous plants in about 60 genera which provide edible fruits (Ananas comosus (L.) Merr., pineapple) and fibres (e.g. Neoglaziovia variegata Mez, caroa). The fruits are either berries or capsules, but in some genera the production of seeds may be comparatively rare. Seed storage behaviour is orthodox.
SEED DORMANCY AND GERMINATION
It can be difficult to germinate the seeds: light treatments generally promote seed germination and scarification can be helpful. Detailed information on seed germination is provided in this chapter for the genera Aechmea and Ananas; for information on Bromelia spp. see Ananas. As a first step in developing suitable germination test procedures for species of unknown characteristics, RBG Kew Wakehurst Place suggests testing in an alternating temperature regime of 23°/9°C (12h/12h), with light applied for 12h/d during the period spent at the upper temperature.
AECHMEA
A. coelestis
A. fasciata
A. nudicaulis
I. Evidence of dormancy
Seeds of Aechmea spp. show orthodox seed storage behaviour, that is they can be dried and then stored at low temperatures (1). The seeds can exhibit dormancy (1).
II. Germination regimes for non-dormant seeds
A. A. coelestis, A. fasciata, A. nudicaulis
Constant temperatures: 20°C (1)
III. Unsuccessful dormancy-breaking treatments
A. coelestis, A. fasciata
Light: dark, at 20°C (1)
A. nudicaulis
Constant temperatures: 15°C, 30°C in light, 200 fc, 1 min-8h/d (1)
Light: dark, at 20°C (1)
IV. Partly-successful dormancy-breaking treatments
A. coelestis
Light: 200 fc, 1,8h/d, at 20°C (1)
A. fasciata, A. nudicaulis
Constant temperatures: 20°C, 25°C in light, 200 fc, 1 min-8h/d (1)
V. Successful dormancy-breaking treatments
A. coelestis
Light: light/dark, 5 min/2h, at 20°C (1)
A. fasciata
Light: red, 2 min, at 20°C (1)
VI. Comment
Light is required for the germination of seeds of Aechmea spp. (1). It is suggested that the seeds be tested for germination on top of filter paper at a constant temperature of 20°C in light - see Chapter 6.
VII. References
1. Downs, R.J. (1964). Photocontrol of germination of seeds of the Bromeliaceae. Phyton, 21, 1-6.
ANANAS
A. comosus (L.) Merr. [A. sativus Schult.f.; Bromelia comosa L.] pineapple
I. Evidence of dormancy
The seeds of pineapple are orthodox, that is they can be stored dry (1,6). Seed germination can be slow (1,2,4,6), the delay being caused by the seed coat (1,2,4-6).
II. Germination regimes for non-dormant seeds
Constant temperatures: 30°-35°C (1,3,6)
III. Unsuccessful dormancy-breaking treatments
Constant temperatures: 20°-28°C (2)
IV. Partly-successful dormancy-breaking treatments
Scarification: concentrated sulphuric acid, 30s (2); concentrated sulphuric acid, 30-60s (4)
V. Successful dormancy-breaking treatments
Scarification: concentrated sulphuric acid, dip, germinate at 35°C (5); concentrated sulphuric acid, 30-60s, germinate at 30°-35°C (1); concentrated sulphuric acid, 1 min, germinate at 32°C (6)
VI. Comment
Seeds of pineapple can be tested for germination on sand or on top of filter papers. Whichever germination test substrate is used it should be sterile, kept moist throughout the test (intermittent mist sprays may be helpful) and well aerated (1-6). It is quite likely that light is required for germination since it has been recommended that the seeds be sown on top of sand (1,3). In addition many other genera within the Bromeliaceae require light for germination. Although very short acid scarification treatments can promote germination, a 30 second treatment in concentrated sulphuric acid can also be detrimental to pineapple seed germination (2).
It is suggested that the seeds be germinated on top of moist (sterile) sand or on top of filter paper at 30°C' in light with regular mist spraying to maintain moisture. Seeds which fail to imbibe within four or five days can be scarified by hand. Alternating temperature regimes may prove to be beneficial.
VII. References
1. Collins, J.L. (1968). The Pineapple. Leonard Hill, London.
2. Gopinomy, R., Balakrishnan, S. and Kannan, K. (1976). A note on germinating seeds of pineapple (Ananas comosus, Merr.). Agricultural Research Journal of Kerala, 14, 194-195.
3. Higgins, J.E. (1916). Germination of pineapple seeds. Hawaii Agricultural Experiment Station Report, pp. 15-17.
4. Iyer, C.P.A., Singh, R. and Subramanyam, M.D. (1978). A simple method for rapid germination of pineapple seeds. Scientia Horticulturae, 8, 39-41.
5. Kerns, K. (1927). Pineapple seed germination. Pineapple News, 1, 38-39.
6. Purseglove, J.W. (1972). Bromeliaceae. In Tropical crops. Monocotyledons, pp. 75-91. Longmans, London.
