Yacón (Polymnia sonchifolia), 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.); Llac�n (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
Yac�n 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 yac�n 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. Compos�es. Encyclop�die scientifique, les plantes � tubercules alimentaires, pp. 339-340. Paris, France: O. Doin et firs, 372 pp.
L�ON, J. 1964. Plantas alimenticias andinas. Instituto Interamericano de Ciencias Agricolas, Zona Andina, Lima, Peru, Bolet�n T�cnico, No. 6, 57-62.
L�ON, 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).
L�ON, 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 ra�ces y tub�rculos tropicales, p. 240. Lima, Peru: Instituto Interamericano de Ciencias Agricolas de la OEA, 284 pp.
