Little published information is available on this subject. Bohorquez (1976) reports germination of 100% after 75 days, for seed collected 1-10 days before sowing; 20-30 days after harvest germination falls to 55% even after 120 days.
In Manaus, germination tests, performed with 8-day old seed, showed that seed from single-seeded fruit started to germinate after 92 days, with 48% of the seeds germinating between 120 and 150 days, and a final germination of 52%. Seeds from double-seeded fruit started to germinate after 55 days, with 41% germinating between 120 and 150 days and a final germination of 64%. Pretreatment of seed in 29°C running water-for 5 days and immersion in a solution of gibberellic acid (100 ppm) for 72 hours, increased final germination to 58% and 68%, respectively, but did not alter germination frequencies (Storti et al. 1989).
Little is known about initial seedling development and size and age of seedling transplant (Bohorquez 1976). Observations to accompany seedling development in different levels of shade during 15 months (Castro et al., in prep.) indicate that:
- in full sun, seedlings develop an average of 9.1 leaves, 7% of the plants were diseased at the end of the period, and average petiole and leaf blade dry weight was 4.9 g and 12.4 g, respectively;- in 50% shade, seedlings develop an average of 7.7 leaves, none of the plants were diseased at the end of the period, and average petiole and leaf blade dry weight was 7.4 g and 14.2 g, respectively; and
- in 70% shade, seedling develop an average of 8.1 leaves, none were diseased, and average petiole and leaf blade dry weight was 13.0 g and 18.9 g, respectively.
The leaf dry weight of individuals growing in 70% shade was, on average, two times greater than that of individuals growing in full sun. These results confirm the observation that, at least in the initial stages of development, the species requires shade. Once "establishment growth" (Tomlinson 1970) is finished, this species, like other Neotropical forest palms (Kahn 1988), requires considerable light (at or near full sunlight) to grow in height and attain sexual maturity, which is also confirmed by the distribution of adult palms in the forest in relation to light (Castro & Lescure, in prep.).
The buriti can be planted in temporarily or permanently flooded soils, if its pneumatophores can reach the air, but will die if these are submersed for too long a period.
Cultivation of buriti for fruit must take into account the dioecious nature of the species. It is currently impossible to determine the sex of a plant before first flowering. Buriti reproductive biology is also poorly understood, so that it is impossible today to estimate the number of male plants that must be maintained to pollinate the females and thus assure satisfactory yields. In Colombia, Urrego (1987) found some natural populations dominated by females (83%), while others were dominated by males (77%), with no-apparent yield reduction in the first case. The destructive harvesting of female plants in Peru is rapidly destroying economically active natural populations, and Kahn (1988) found female: male ratios of 3: 15 and 23: 100 in some 1 ha plots in the lower Ucayali River. Relative production of these females was unreported but could supply some of the requisite information.
Management of the buriti zones appears to be a simple process. Some suggestions are presented for research and development:
1. Female plants should not be cut. Climbing bicycles or similar technologies should be made available to buriti collectors.2. Male plants can be thinned to leave 15-20% males in the population, based upon Urrego's (1987) observations.
3. Nonuseful dicots or other palms can also be thinned or eliminated, leaving only other useful dicots or palms (eg. Euterpe oleracea, Jessenia bataua, Virola surinamensis, etc). This would open space for buriti, thus probably enhancing fruit yields.
4. Mass selected seed from the best quality buriti in each buriti zone should be sown directly or prepared in nurseries and transplanted into open areas in the buriti zone to improve the quality of the population. When these plants start to fruit, the males can be thinned to attain the 15-20% mentioned above.
Dr. Aline de Castro, Departamento de Ecologia, INPA, current address: ORSTOM; Clos du Val de Montferrand; 274, Rue Sonja Henrie; 34090 Montpellier, France.
Dr. Isolde Ferraz, Departamento de Silvicultura, Instituto Nacional de Pesquisas da Amazônia - INPA, Caixa Postal 478, 69.011, Manaus, Amazonas, Brazil.
Dr. Lidio Coradin, Centro Nacional de Recursos Genéticos e Biotecnologia - CENARGEN/EMBRAPA, Caixa Postal 10.2372, 70.770 Brasília, DF, Brazil.