Index | Search | Home
new crop logo

Prosopis alba Grisebach

Mimosaceae
Algarrobo Blanco, Ibope, Igope, Tacu

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. References

Uses

All information, especially early information, on Prosopis spp. is only tentatively assigned to one or the other species of Prosopis. Taxonomic identities were extremely confused until Burkart's monograph. Much of the early chemical, ecological, and ethnobotanical data may be masquerading under the wrong name. Burkart (1943) describes several beverages made from the fruits, including a coffee substitute made from toasted pods. A very important tree in arid lands, similar in value to Prosopis chilensis, P. nigra, or P. pallida. In northeastern Argentina, native people frequently call it "el arbol", the tree, because of its usefulness and abundance. It is cultivated to a limited extent. In the Chaco it furnishes timber of high value for construction, doors, premanufactured houses, etc. Trees with straight trunks 8 to 10 m occur, but these are becoming extremely rare, from being cut in preference to the other shorter ones. Thus a negative, artificial selection is taking place, which should be counteracted by genetic up-building of the best lines in experimental plots (Burkart, 1976). According to NAS (1980a) this valuable food tree is also used for fodder, roadside planting, timber, and windbreaks. Streets of Buenos Aires are lined with these trees in the belief that they subdue vehicular noises (Burkart, 1943). The fruit is milled into a baking flour for human consumption. Though difficult to work, the wood is used for flooring, paving blocks, shoe lasts, and wine casks. Sawdust, like the fruits is used for tanning.

Folk Medicine

Reported to be astringent, lithontriptic, and tonic, the white algarrobo is a folk remedy for ophthalmia.

Chemistry

Per 100 g, the pericarp only (of P. alba and P. velutina) is reported to contain 4 g H2O, 10 g protein, 40 g sugar, and 19 g fiber. "Patay" is the sweet floury paste of the pods, ground up and dried, serving as the basis for many popular Argentine dishes. Patay contains 9.6% water, 6.7% ash, 43.9% sugar, 10.4% starch, 5.9% cellulose (we need it), 4.3% protein, 1.2% fats, and 3.5% pentosans. While high in calories, the patay is deficient in certain proteins, vitamin A, C, and D (Burkart, 1943). Like P. chilensis, this species contains apigenin 8-glucoside, apigenin 6-glucoside, quercitin 3-glucoside, quercitin 3-rhamnoside, quercitin 3-rutinoside, and traces of myricetin 3-rhamnoside, luteolin, kaempferol-3-OMe quercetin, and quercitin 3-OMe (Simpson, 1977). Pipecolic and 4-hydroxy pipecolic acid also occur in both, but varying concentrations of pipecolic acid and proline are interpreted as reflecting a plastic response to changing environmental conditions. The consistent patterns of flavonoid distributions in several species groups, on the other hand, apparently reflects genetic fixation independent of known environmental factors (Simpson, 1977). Pods contain ca 7–11% protein, 25–28% sugar (Simpson, l977; Burkart, 1943).

Description

Tree 5–15 m tall, in age the short trunk possibly reaching 1 m in diameter; treetop rounded; branchlets drooping; spines scarce and small, only on strong shoots, 2–4 cm long, geminate. Leaves large, uni- to trijugate, glabrous; petiole (including the rachis) 0.5–8 cm long; pinnae 6–14 cm long, with 25 to 50 pairs of leaflets, these linear, acute or subacute, in some forms nearly obtuse, 0.5–1.7 cm long x 1–2 mm broad, scarcely nerved below, approximate, 1.5–6 mm between pairs. Racemes spikelike as in similar species, 7–11 cm long; florets greenish-white to yellowish, small; calyx 1 mm long, puberulous; corolla 3–3.2 mm; stamens 4.5 mm; pistil 5 mm long. Legume falcate to ring-shaped (ring ca 7 cm in diameter), linear, compresses with parallel margins, straw-yellow, stipitate and acuminate, 12–25 cm long x 11–20 mm broad x 4–5 mm thick, with 12 to 30 subquadrate endocarp segments broader than long, ca 0.6 x 1 cm (Burkart, 1976).

Germplasm

Reported from the South American Center of Diversity, white algarrobo, or cvs thereof, is reported to tolerate drought, salt, and sand, but it will withstand only a few hours of mild frost, prolonged cold (-6°C) killing most seedlings. Said to hybridize with P. flexuosa, P. nigra, and P. ruscifolia. In terms of chromosome number and morphology, there seem to be few genetic or chromosomal barriers to hybridization between various species of Prosopis. Sympatry, partial overlap of flowering time, and little specific discrimination by pollinating insects also facilitate hybridization (2n = 28) (Simpson, 1977).

Distribution

Plains of subtropical Argentina to Uruguay, Parguay, southern Brazil to Peru (Burkart, 1976).

Ecology

Our computer entries for Prosopis spp. are unreliable partly due to past taxonomic confusion. I estimate that the species ranges from Tropical Thorn to Moist through Subtropical Thorn to Moist Forest Life Zones. It will probably tolerate annual precipitation of 1 to 20 dm, annual temperature of 18 to 28°C, and pH of 6 to 8.5. Felker et al. (1981) cite studies suggesting that the annual minimum temperature isotherm of minus 20.5°C defines the northern limit for Prosopis distribution generically.

Cultivation

Tree can be seeded directly but is best sown in a nursery and outplanted when 2–3 months old. For quick germination (3–4 days), high temperatures (night 26°C; day 32°C) are best. Running the pods through a coarse sausage grinder both helps to separate and scarify the seed. Felker et al. (1981) found that a coffee mill produced fewer broken seed than the other devices they tested. Felker et al (1981) report water requirements of 478.3 cm /g DM, making this one of the more water efficient species. Felker et al. (1981) report the first successful rootings of mesquite cuttings. Seed need to be inoculated with mesquite rhizobia. Competes well with grasses and shrubs.

Harvesting

This species, like P. nigra, has good coppicing qualities. Felker et al (1981) project costs of $23.36 per dry ton (on the stump from tissue cultured seedlings) for the first harvest and only $5.00 per dry ton for subsequent coppice regrowth harvests. Firewood harvested as needed.

Yields and Economics

The three Prosopis accessions with greatest potential for woody biomass production in semi-arid southwestern US are P. alba, P. chilensis, and P. articulata. P. alba (#0166) had highest biomass production of the three selections, had good coppicing characteristics, and low psyllid insect damage. It has been successfully rooted from cuttings. Thorn free selections have been observed. One tree survives where a 5 mm salt layer covers the ground and a mature tree survived a -9°C (16°F) frost. It may prove more frost hardy than either P. articulata (#0016) or P. chilensis (#0009). Felker et al (1981) feel that progeny of Prosopis alba accessions used for ornamentals are most promising for woody biomass production in arid lands despite impressive biomass production by Leucaena and Parkinsonia. They report yields of 50 MT DM/ha in 3 years or nearly 17 MT/ha/yr, a yield sufficiently high to make effective use of harvesting and transportation equipment. Felker et al. (1981) give detailed economic projections in their table, Projected Costs for Mesquite Pod Production. Perhaps even more important, they talk about total use of the pods, fractionating for mesquite pod gum, protein, and sugar to realize their full economic potential. Galactomannan gums, estimated to constitute 25% of the seeds of some Prosopis species have many cosmetic, chemurgic, and food uses. The gum is fairly similar to carob gum, which commanded $0.62–1.11/kg in 1970. Way back in the 40's, the mildly intoxicant beverage, aloja, was made from fruits sold in the market for 30 Argentine centavos/kg. The fermented aloja was further distilled into aguardiente or ethanol. To produce a liter of absolute alcohol requires 1.7 kg fermentable sugar, which constitute about 3/4 of the fruit's weight (Burkart, 1943).

Energy

Burkart (1943) suggests that a ton of fruit could yield 27.2 liters of absolute alcohol. Felker et al (1981) state that the land area required for a small commercial ethanol production plant (1,000 barrels/day) could be contained in a circle with radius of 10.9 km assuming conversion rate of 2.6 gallons ethanol per 55 pounds pods (much higher than Burkart's assumptions) and yields of 4,000 lb/acre. Ca 12% of the land would provide firewood for distillation. Ten year old Argentinean plantations spaced at 2 x 2 m produced 7 m /ha/yr (NAS, 1980a). Felker et al (1981) report yields from 9.8–19.2 MT/ha/yr in the Imperial Valley.

Biotic Factors

Bruchids associated with this species include Rhipibruchus, Pectinibruchus, and Scutobruchus. Spraying cuttings with dithane suspensions has markedly reduced problems with the fungus Alternaria (Felker et al., 1981). Felker et al. (1981) review the pest infestations of their Prosopis plantings with suggestions for their control.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Jaunary 8, 1998 by aw