Yacón (Polymnia sonchifolia)
Common names
YACÓN, Jiquima.
Botanical name
Polymnia sonchifolia Poepp. and Endl. syn. P. edulis Wedd.
Family
Compositae.
Other names
Arboloco (Col.); Aricoma, Aricuma (Peru, Bol.); Jiquimilla
(Venez., Col.); Llacón (Arg., Bol., Peru); Poire de terre cochet (Fr.);
Botany
A herbaceous plant, the stem of which is composed of a
subterranean perennial part, which gives rise to annual aerial stems. The tall
aerial stems are covered with fine hairs and green in colour with purple spots
and can reach about 1.5 m in height. The leaves are opposite, thin and smooth,
with serrated edges. From the lower leaf axils additional stems arise and at the
end of these stems the yellow or orange-yellow composite flowers are borne. The
subterranean part of the main stem thickens to give rise to the tubers which are
usually ellipsoid or cylindrical in shape.
Origin and distribution
The plant originated in the central Andes, and has from early
prehistoric times been cultivated in the cool conditions of the subtropical and
tropical Andes, at elevations between 1 000 and 3 300 m in Peru, Bolivia,
Colombia and north-west Argentina.
Planting procedure
Material-propagated vegetatively from sprouting runners (slips),
about 10-20 cm long, taken from the base of the main stem with a few roots
attached.
Method-the slips are planted throughout the year, provided there is
adequate soil moisture, and receive little attention apart from being kept free
from weeds.
Growth period
The crop reaches maturity in about 7 months.
Harvesting and handling
The tubers are lifted by hand and, if kept in a dark, dry place,
can be stored for several months.
Primary product
Tubers-the tuberous fusiform roots are edible and can reach 20
cm in length and 3-10 cm in diameter, and weigh up to 2 kg though 100-500 g is
more usual. There is considerable variation in the form and composition
according to the cultivar, but most have a soft purplish, bark-like skin and can
be spheroid or ellipsoid with somewhat translucent yellow flesh.
Yield
Yields of up to 38 t/ha have been reported.
Main use
Yacón is used as a vegetable and may be cooked or eaten raw;
sometimes the tubers are dried in the sun before cooking, since this is said to
sweeten them and improve their flavour.
Subsidiary uses
The tubers may be used as a source of inulin or fermented to
produce alcohol.
Secondary and waste products
The main stem is also eaten as a vegetable and the dried leaves,
which have a protein content of approximately 11-17 per cent, are used as an
animal feedingstuff.
Special features
An analysis of the edible portion of the tubers has been quoted
as: water 69.5-82.7 per cent; protein 0.44-2.22 per cent; nitrogen-free extract
2.65 10.5 per cent; fat 0.1-0.13 per cent; carbohydrate 19.67 per cent; fibre
0.28-1.75 per cent; ash 0.26-2.04 per cent.
The carbohydrate consists mainly of inulin, and contents ranging
from 61 to 69 per cent have been obtained for the dry roots.
Major influences
It has been suggested that the yacón could be a useful fodder
crop for cultivation at high altitudes in the tropics or subtropics. This plant
is high in priority for conservation of genetic resources.
Bibliography
CALVINO, M. 1940. Una nuova planta de forragio e da alcole, la
Polymnia edulis. [A new plant Polymnia edulis for forage or alcohol.] Industria
Saccarifera Italiana 33, 94-98. (Chemical Abstracts, 34 (13), 4481).
ESQUINAS-ALCAZAR, J. T. 1982. Phytogenetic resources of the
Andean region. 4. The phytogenetic resources of Ecuador. Plant Genetic Resources
Newsletter, No. 51, pp. 31-34. Rome, Italy: Food and Agriculture Organization of
the United Nations, 43 pp.
JUMELLE, H. 1910. Composées. Encyclopédie scientifique, les
plantes à tubercules alimentaires, pp. 339-340. Paris, France: O. Doin et firs,
372 pp.
LÉON, J. 1964. Plantas alimenticias andinas. Instituto
Interamericano de Ciencias Agricolas, Zona Andina, Lima, Peru, Boletín Técnico,
No. 6, 57-62.
LÉON, J. 1967. Andean tuber and root crops: origin and
variability. Proceedings of the International Symposium on Tropical Root Crops
(Trinidad, 1967) (Tai, E. A., Charles, W. B., Haynes, P. H., Iton, E. F. and
Leslie, K. A., eds), Vol. 1, Section 1, pp. 118-123. St. Augustine, Trinidad:
University of the West Indies (2 vole).
LÉON, J. 1977. Origin, evolution and early dispersal of root and
tuber crops. Proceedings of the 4th Symposium of the International Society for
Tropical Root Crops (Colombia, 1976), IDRC-080e (Cock, J., MacIntyre, R. and
Graham, M., eds), pp. 20-36. Ottawa, Canada: International Development Research
Centre, 277 pp.
MONTALDO, A. 1972. Aricuma. Cultivo de raíces y tubérculos
tropicales, p. 240. Lima, Peru: Instituto Interamericano de Ciencias Agricolas
de la OEA, 284
pp.
