Urucum (Bixa orellana) - species description

Urucum (Bixa orellana L., Bixaceae) (Figs. 1 and 2) (urucu (Bras.); annatto (or anato) plant (Engl.), Orleansbaum (German)) is an understory shrub, whose seeds are processed to obtain the red pigments bixin (1.6 to 6.9% of seeds dry weight (Falesi & Kato 1992)) and norbixin as a dye for foods and cosmetics.

Fig. 1 Inflorescence of flowers of urucum with several young fruit (left), opened fruit exposing the seeds which outer cover consists of the pigment processed (right).

Production of seeds reaches a plateau of about 2400 kg/ha after about 6 years (at 400 shrubs/ha). First harvest is after one to two years with about 200 kg/ha (Baliane 1982).

The total production of the urucum-seeds in Brazil increased from 972 t in 1984 to 7332 t in 1989 (with about 10% water content) (Falesi & Kato 1992, referring to IBGE 1985, IBGE 1986, IBGE 1988, and IBGE 1989). Mean price for seeds exported from Brazil in 1987 was $ 1.57 per kg. This low price motivated many smallholders to give up their plantings, but production in total still is increasing. Since content of bixin varies strongly (see above), selection of varieties is promising and thus carried out. Urucum is a plant well adapted to the poor and acid soils of tropical America, but it responds well to fertilization (Falesi & Kato 1992, referring to Kato et al. 1989) and performs excellent in full sun. Main production came from the state of São Paulo in the south of Brazil followed by Paraíba and Pará; in Amazônas the production is still in the beginning (Falesi & Kato 1992). The species is also cultivated in India, Sri Lanka and Java. Urucum is not severely affected by pests or diseases (Baliane 1982).

Urucum is inhabited in the understory of the humid forests of tropical America; it reaches a height of 2 to 6 m and an age of up to about 50 years, commercial life-time is about 30 years (Baliane 1982). Urucum is more tolerant to drought than the other species described above; it is also found on drier habitats (Schmidt 1996). The shrub has been used by the Indians since pre-Columbian times as coloring, sunscreen and to treat insect-stings and is distributed throughout tropical America.

Urucum usually is pruned annually to induce a richer harvest and to maintain a size where the harvest is made easier. This pruning is also carried out in the SHIFT experiment. The flowers are pollinated by a variety of Hymenoptera (several species of the Anthophoridae and Apidae). The ripe fruit (called cachopas), that are grouped together in about 5 to 20 per inflorescence have to be harvested before getting brown. This is accompanied with infection by fungi and/or germination. The seeds are extracted manually or mechanically. The bixin is situated in a < 0.1 mm thin outer layer surrounding the seed (Falesi & Kato 1992).

Regarding allometrics, the short and slightly tortuous, often inclined stem of irregular cross-sectional view is of importance. Since the shrub is pruned regularly (to a certain shape and height) the remaining aboveground biomass is thought to be somewhat homogenized within the years among trees of different growth. Since pruning is carried out by different personnel the proportion of biomass cut can be assumed to depend also on subject criteria. The amount of material pruned depends on both reserves after pruning and (mainly) on actual growth in the present year. This is why this fraction varies stronger among individual plants.