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Ullucus
Ullucus tuberosus
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Tracheophytes
(unranked):	Eudicots
Order:	Caryophyllales
Family:	Basellacae
Genus:	Ulucus
Species:	Ulucus tuberosus

1. Description

Ullucus is a genus of flowering plants in the Basellaceae family, with one species, Ullucus tuberosus, a plant grown primarily as a root vegetable, secondarily as a leaf vegetable. The name ulluco is derived from the Quechua word ulluku, but depending on the region, it has many different names. These include illaco (in Aymara), melloco (in Ecuador), chungua or ruba (in Colombia), papa lisa (in Peru) or Ulluma (in Argentina).

Olluco is one of the most widely grown and economically important root crops in the Andean region of South America, second only to the potato. The tuber is the primary edible part, but the leaf is also used and is similar to spinach. They are known to contain high levels of protein, calcium, and carotene. Olluco was used by the Incas prior to arrival of Europeans in South America. The scrambling herbaceous plant grows up to 500mm high and forms starchy tubers below ground. These tubers are typically smooth and can be spherical or elongated. Generally they are a similar size to the potato however have been known to grow up to 15cm long. Due to its brightly coloured waxy skin in a variety of yellows, pinks and purples, Ullucus tubers are regarded as one of the most striking foods in the Andean markets.

Ullucus tuberosus has a subspecies, Ullucus tuberosus subsp. aborigineus, which is considered a wild type. While the domesticated varieties are generally erect and have a diploid genome, the subspecies is generally a trailing vine and has a triploid genome.

2. Origin

It is probable that ulluco was brought into cultivation more than 4000 years ago. Biological material from several coastal peruvian archaeological sites have been found to contain starch grains and xylem of the ulluco plant, suggesting domestication occurred between the central Andes of Peru and Bolivia. Illustrations and representations of ulluco on wooden vessels (keros), ceramic urns and sculptures have been used to date the presence and importance of these tubers back to 2250 BC.

Although it lost some importance due to the influx of European vegetables following the Spanish conquest in 1531, Ulluco still remains a staple crop in the Andean regions. However, in comparison to the potato which is now cultivated in over 130 countries, outside of South America the ullucus tubers are still relatively unknown. Initial attempts were made to cultivate it in Europe in the 1850s following the potato blights but were not successful on a large scale due to its requirements for cultivation.

3. Importance and uses

Ullucos are cultivated for their edible tubers by subsistence farmers in high altitude farming systems around 2500 to 4000m above sea level. The tubers are usually eaten in indiginous soups and stews but more contemporary dishes incorporate them into salads along with the ulluco leaves. These tubers have been eaten in the Andean populations since ancient times and still to this day provide an important protein, carbohydrate and vitamin C source to people living in the high altitude mountainous regions of South America.

The major appeal of ulluco is its crisp texture which, like the jicama, remains even when cooked. Because of its high water content, ulluco is not suitable for frying or baking, but it can be cooked in many other ways like the potato. In the pickled form, it is added to hot sauces. It is the main ingredient in the classic Peruvian dish olluquito con ch'arki and a basic ingredient together with the mashua in the typical Colombian dish cocido boyacense. They are generally cut into thin strips.

In order to increase their shelf life, a typical product is produced by the Quechua and Aymara communities in Peru called Chuño or lingli. This is produced via a process involving environmental freezing and drying which is usually then ground into a fine flour and added to cooked foods.

4. Production

4.1. Climate requirements

Ullucu is normally propagated vegetatively by planting small whole tubers. However, they are also easily propagated by stem or tuber cuttings. They prefer cooler climates and will produce much better yields in full sun where summer temperatures are relatively cool. They are also known to grow in hotter regions when covered with shade. They are short day plants which require around 11-13.5 hours of day length. However, due to the inherent diversity of ulluco, sun exposure needs vary among cultivars and location. As the day length shortens, stolons grow out of the stems and then develop into tubers.

4.2 Fertilization, chemical growth, regulators, field management

Ullucus is grown in the highlands and can survive in altitudes of up to 4200m above sea level. Indigenous Andean farmers regularly grow a large number of different cultivars of ulluco together in the same fields. Ulluco crop is alternated with two other Andean tuber crops known as ‘oca’ and maschua’. These different tubers are planted together in relatively small field and harvested after approximately 8 months. The different species are then separated following harvest.

4.3 Harvest and postharvest treatment

Ullucus tubers need to be dug by hand due to their sensitivity to scaring. Due to the importance of their appearance, scuffing of their skin is likely a problem. Under traditional cultivation conditions, yield range from 5-9 tons per hectare however in intensive systems, they have been known to reach 40 tons per hectares. These tubers can be stored year-round in the Andes but are best stored in the dark as exposure to the sun can cause fading of their vibrant colouring.

Usually a proportion of the smaller tubers from the harvest are preserved for use as seed tubers the following year. The remainder of the harvest is most often used for consumption however there has been an increasing trend for ullucu use as a cash crop at the markets.