Oxalis tuberosa | |
---|---|
Yellow and purple O. tuberosa tubers | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Oxalidales |
Family: | Oxalidaceae |
Genus: | Oxalis |
Species: | O. tuberosa |
Binomial name | |
Oxalis tuberosa | |
Oxalis tuberosa is a perennial herbaceous plant that overwinters as underground stem tubers. These tubers are known as uqa in Quechua, [1] oca in Spanish, yams in New Zealand and several other alternative names. The plant was brought into cultivation in the central and southern Andes for its tubers, which are used as a root vegetable. The plant is not known in the wild, but populations of wild Oxalis species that bear smaller tubers are known from four areas of the central Andean region. [2] Oca was introduced to Europe in 1830 as a competitor to the potato, and to New Zealand as early as 1860.
In New Zealand, oca has become a popular table vegetable and is called yams (although not a true yam). It is available in various colors, including yellow, orange, pink, apricot, and traditional red. [3]
Grown primarily by Quechua and Aymara farmers, oca has been a staple of rural Andean diets for centuries. [4] Of all Andean root and tuber crops, oca is currently second only to potato in area planted within the Central Andean region. [3] Oca is essential to local food security because of its role in crop rotations and its high nutritional content.
Andean farmers, including the indigenous Quechua and Aymara people, cultivate numerous varieties of oca. [5] Oca diversity may be described with respect to morphological characters, local cultivar names, or molecular markers.
Oca morphotypes are distinguished by foliar, floral, fruit, stem, and tuber characteristics, as described in the International Plant Genetic Resources Institute's document on oca descriptors. [6] The morphological diversity of oca tubers, in particular, is astounding. Tubers range from 25 to 150 mm in length by 25 mm in width; [7] skin and flesh color may be white, cream, yellow, orange, pink, red, and/or purple and distributed in range of patterns. [6]
Oca-growing communities often name varieties based primarily on tuber morphology [8] and secondarily on flavor. [2] For example, common names may include ushpa negra (black ash) or puka panti (red Cosmos peucedanifolius). Great inconsistency of nomenclature has been reported within and among communities. [9]
Numerous studies have additionally described oca diversity through molecular approaches to study protein and genetic variation. Molecular markers, such as allozymes (e.g., del Río, 1999 [10] ) and inter-simple sequence repeats (e.g., Pissard et al., 2006 [11] ), show oca diversity to be low relative to other crops, probably because of its vegetative mode of propagation. While genetic differentiation corresponds well with folk classification, [12] cluster analyses indicate that folk cultivars are not perfect clones, but rather genetically heterogeneous groupings. [11] [12]
Oca is cultivated primarily for its edible stem tuber, but the leaves and young shoots can also be eaten as a green vegetable. Mature stems can be used similarly to rhubarb. [13] Andean communities have various methods to process and prepare tubers, and in Mexico oca is eaten raw with salt, lemon, and hot pepper. [3] The flavor is often slightly tangy, but there is a considerable degree of flavor difference between varieties, and some are not acidic. [14] Texture ranges from crunchy (like a carrot) when raw or undercooked, to starchy or mealy when fully cooked.
Oca is fairly high in oxalates, concentrated in the skin. [15] Significant variation in oxalate concentration exists among varieties, and this variation distinguishes two oca use-categories recognized by Andean farmers. [2]
One use category, sour oca, contains cultivars with high oxalic acid levels. [2] Farmers process these tubers to form a usable storage product called khaya in Quechua. [12] tubers are first soaked in water for approximately one month to prepare khaya. Then they are left outside during hot, sunny days and cold, freezing nights until they become completely dehydrated. [12] This process is similar to the preparation of chuñu from bitter potatoes. Cultivars in this use category are referred to in Quechua as khaya (name of the dried, processed product) or p'usqu (sour/fermented), [12] and in Aymara as luk’i. [2]
The other use category, sweet oca, contains cultivars with lower oxalic acid levels. [2] The traditional Andean preparation methods for this use category are also geared towards reducing the oxalate level of the harvested vegetable, but without dehydration. This is done by exposure to sunlight, which decreases the organic acid content and increases the oca's sweet taste.
nutrient per 100 g | fresh | dried |
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Energy | 255 kJ (61 kcal) | 1,360 kJ (330 kcal) |
Water (g) | 84.1 | 15.3 |
Protein (g) | 1.0 | 4.3 |
Carbohydrates (g) | 13.3 | 75.4 |
Ash (g) | 1.0 | 3.9 |
Calcium (mg) | 2 | 52 |
Phosphorus (mg) | 36 | 171 |
Iron (mg) | 1.6 | 9.9 |
Retinol (μg) | 1 | 0 |
Riboflavin (mg) | 0.13 | 0.08 |
Niacin (mg) | 0.43 | 0.85 |
Vitamin C (mg) | 38.4 | 2.4 |
Once exposed to sunlight, oca can be boiled, baked, or fried. In the Andes it is used in stews and soups, served like potatoes, or can be served as a sweet. Cultivars in this category are referred to in Quechua as wayk'u (boiling), misk'i (sweet/delicious) and in Aymara as q'ini. [2]
Sour oca and sweet oca form distinct genetic clusters based on AFLP data. [16] This suggests the possibility of distinct evolutionary histories for each use-category.
Oca is a source of carbohydrates, dietary minerals, and protein. [17] [18] Cultivars vary substantially in nutritional content. [18]
Oca is one of the important staple crops of the Andean highlands due to its easy propagation and tolerance for poor soil, high altitude, and harsh climates. [3]
Oca is planted in the Andean region from Venezuela to Argentina, [19] from 2800 to 4100 meters above sea level. [12] Its highest abundance and most extraordinary diversity are in central Peru and northern Bolivia, the probable area of its domestication. [20]
Oca needs a long growing season and is day length dependent, forming tubers when the day length shortens in autumn (around March in the Andes). In addition, oca requires climates with average temperatures of approximately 10 to 12 °C (ranging between 4 and 17 °C) and average precipitation of 700 to 885 millimeters per year. [21]
Oca requires short days to form tubers. Outside the tropics, it will not begin to form tubers until approximately the autumn equinox. The plant will die before producing tubers if frosts occur too soon after the autumn equinox. [3]
Oca grows with very low production inputs, generally on plots of marginal soil quality, and tolerates acidities between about pH 5.3 and 7.8. [3] In traditional Andean cropping systems, it is often planted after potato and therefore benefits from persisting nutrients applied to, or leftover from, the potato crop. [21]
Oca is usually propagated vegetatively by planting whole tubers.
Propagation by seed is possible but is rarely used in practice. [3] Sexual propagation is complicated by several factors. First, like many other species in the genus Oxalis, oca flowers exhibit tristylous heterostyly and are consequently subject to auto-incompatibility. [22] Furthermore, on the rare occasion that oca plants do produce fruit, their loculicidal capsules dehisce spontaneously, making it difficult to harvest seed. [22] Oca flowers are pollinated by insects (e.g., genera Apis, Megachile , and Bombus ). [22]
Oca tuber seeds are planted in the Andes in August or September and harvested from April to June. [21] The first flowers bloom around three to four months after planting, and the tubers also begin to form. [22] Between planting and harvesting, the oca crop requires little tending, except for a couple of weedings and hillings. [21]
Oca is a component of traditional crop rotations and is usually planted in a field directly after the potato harvest. A standard sequence in this rotation system may be one year of potato, one year of oca, one year of oats or faba beans, and two to four years fallow. [21] Within this system, q’allpa is a Quechua term that signifies soil previously cultivated and prepared for the planting of a new crop. [21]
The cultural practice is similar to potatoes. Planting is done in rows or hills 80–100 cm apart, with plants spaced 40–60 cm apart in the rows. [23] Monoculture predominates, but interplanting with several other tuber species, including mashua and olluco, in one field is common in Andean production. Often, this intercropping consists of several different varieties of each species. Such mixed fields may later be sorted into tuber types during harvest or before cooking. [3]
Yields vary with the cultural method. Annals from Andean countries report about 7-10 tonnes per hectare of O. tuberosa production. However, with adequate inputs and virus-free propagation material, oca production can range from 35 to 55 tonnes per hectare. [3] [19]
Pests and diseases limit the production of oca. Crops in the Andes are often infected with viruses, causing chronic yield depression. Adequate techniques to remove viruses have to be applied before the varieties can be used outside the Andean region. [3] Cultivation is also constrained by the Andean potato weevil (Premnotrypes spp), ulluco weevil (Cylydrorhinus spp), and oca weevil, the identification of which remains uncertain (possibly Adioristidius, Mycrotrypes, or Premnotrypes). These weevils often destroy entire crops. Further notable pests are nematodes. [19]
As already mentioned, both day-length restrictions and the presence of oxalates can also be considered limiting factors. Scientists work with specific breeding, selection, and virus-cleaning programs for these purposes. [3]
Several ongoing ex situ and in situ conservation projects currently focus on the preservation of O. tuberosa diversity. [24] The International Potato Center (CIP) in Peru has several hundred accessions of oca collected from regions in Bolivia, Argentina, and Peru to help ensure and maintain diversity. There are further efforts to collect accession of oca in regions where habitat destruction and pests threaten the diversity of wild oca accessions.
The potato is a starchy root vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are tubers of the plant Solanum tuberosum, a perennial in the nightshade family Solanaceae.
The sweet potato is a dicotyledonous plant that belongs to the bindweed or morning glory family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a root vegetable. The young shoots and leaves are sometimes eaten as greens. Cultivars of the sweet potato have been bred to bear tubers with flesh and skin of various colors. Sweet potato is only distantly related to the common potato, both being in the order Solanales. Although darker sweet potatoes are often referred to as "yams" in parts of North America, the species is even more distant from the true yams, which are monocots in the order Dioscoreales.
Quinoa is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins and dietary minerals in amounts greater than in many grains. Quinoa is not a grass but rather a pseudocereal botanically related to spinach and amaranth, and originated in the Andean region of northwestern South America. It was first used to feed livestock 5,200–7,000 years ago, and for human consumption 3,000–4,000 years ago in the Lake Titicaca basin of Peru and Bolivia.
Root vegetables are underground plant parts eaten by humans as food. In agricultural and culinary terminology, the term applies to true roots such as taproots and tuberous roots as well as non-roots such as bulbs, corms, rhizomes, and stem tubers.
Arracacia xanthorrhiza is a root vegetable that originates in the Andes, whose starchy taproot is a popular food item across South America where it is a major commercial crop.
Ullucus is a genus of flowering plants in the family Basellaceae, 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, melloco, chungua or ruba, olluco or papalisa, or ulluma.
The yacón is a species of daisy traditionally grown in the northern and central Andes from Colombia to northern Argentina for its crisp, sweet-tasting, tuberous roots. Their texture and flavour are very similar to jícama, mainly differing in that yacón has some slightly sweet, resinous, and floral undertones to its flavour, probably due to the presence of inulin, which produces the sweet taste of the roots of elecampane, as well. Another name for yacón is Peruvian ground apple, possibly from the French name of potato, pomme de terre. The tuber is composed mostly of water and various polysaccharides.
Tropaeolum tuberosum is a species of flowering plant in the family Tropaeolaceae, grown in the Andes, particularly in Peru and Bolivia, and to a lesser extent in Ecuador as well as in some areas of Colombia, for its edible tubers, which are eaten cooked or roasted as a vegetable. It is a minor food source, especially for native Amerindian populations. Mashua is a herbaceous perennial climber growing to 2–4 m (7–13 ft) in height. It is related to garden nasturtiums, and is occasionally cultivated as an ornamental for its brightly coloured tubular flowers.
Pachamanca is a traditional Peruvian dish baked with the aid of hot stones. The earthen oven is known as a huatia. It is generally made of lamb, mutton, alpaca, llama, guanaco, vicuna, pork, beef, chicken, or guinea pig, marinated in herbs and spices. Other Andean produce, such as potato or chuño, habas, sweet potato, mashua, oca, ulluco, cassava, yacon, plantain, humitas, ears of corn, and chilli, are often included in the baking.
Quechua people or Quichua people may refer to any of the indigenous peoples of South America who speak the Quechua languages, which originated among the Indigenous people of Peru. Although most Quechua speakers are native to Peru, there are some significant populations in Ecuador, Bolivia, Chile, Colombia, and Argentina.
Chuño is a preserved potato product traditionally made by Quechua and Aymara communities of Bolivia and Peru, and is known in various countries of South America, including Bolivia, Peru, Chile and Northwest Argentina. It is a five-day process, obtained by exposing a bitter, frost-resistant variety of potatoes to the very low night temperatures of the Andean Altiplano, freezing them, and subsequently exposing them to the intense sunlight of the day. The word comes from Quechua ch'uñu, meaning 'frozen potato'.
The Yungas is a bioregion of a narrow band of forest along the eastern slope of the Andes Mountains from Peru and Bolivia, and extends into Northwest Argentina at the slope of the Andes pre-cordillera. It is a transitional zone between the Andean highlands and the eastern forests. Like the surrounding areas, the Yungas belong to the Neotropical realm; the climate is rainy, humid, and warm.
Yam is the common name for some plant species in the genus Dioscorea that form edible tubers.
When the Spanish arrived, they divided Peru into three main regions: the coastal region, that is bounded by the Pacific Ocean; the highlands, that is located on the Andean Heights, and the jungle, that is located on the Amazonian Jungle. But Javier Pulgar Vidal, a geographer who studied the biogeographic reality of the Peruvian territory for a long time, proposed the creation of eight Natural Regions. In 1941, he presented his thesis "Las Ocho Regiones Naturales del Perú" at the III General Assembly of the Pan-American Institute of Geography and History.
Inca agriculture was the culmination of thousands of years of farming and herding in the high-elevation Andes mountains of South America, the coastal deserts, and the rainforests of the Amazon basin. These three radically different environments were all part of the Inca Empire and required different technologies for agriculture. Inca agriculture was also characterized by the variety of crops grown, the lack of a market system and money, and the unique mechanisms by which the Incas organized their society. Andean civilization was "pristine"—one of six civilizations worldwide which were indigenous and not derivative from other civilizations. Most Andean crops and domestic animals were likewise pristine—not known to other civilizations. Potatoes and quinoa were among the many unique crops; Camelids and guinea pigs were the unique domesticated animals.
The vertical archipelago is a term coined by sociologist and anthropologist John Victor Murra under the influence of economist Karl Polanyi to describe the native Andean agricultural economic model of accessing and distributing resources. While some cultures developed market economies, the predominant models were systems of barter and shared labor. These reached their greatest development under the Inca Empire. Scholars have identified four distinct ecozones, at different elevations.
Pachyrhizus ahipa, also called the ahipa or Andean yam bean, is a tuberous root-producing legume, which is distributed mainly in the Andean region.
Olluquito, olluquito con carne and olluquito con ch'arki are traditional dishes in Peruvian cuisine made with ulluku a root vegetable that also has edible leaves. It is an important root crop in the Andean region of South America, second only to the potato. The leaf and the tuber are edible; the leaves are similar to spinach, and the root is like a potato or jicama. The Ulluku contains high levels of protein, calcium, and carotene. Papalisa were used by the Incas prior to arrival of Europeans in South America. It can be served with meat.
Current agricultural practices of the Andean region of South America typically involve a synthesis of traditional Incan practices and modern techniques to deal with the unique terrain and climatic elements of the area. Millions of farmers in economically impoverished communities make a living producing staple crops such as potato, olluco, and mashua for their own consumption as well as profit in local and urban markets. The Andean region is particularly known for its wide variety of potato species, boasting over about 5,000 varieties identified by the International Potato Center based in Peru. These crops are arranged within the mountains and plateaus of the Andes in four distinct landscape-based units described as Hill, Ox Area, Early Planting, and Valley which overlap one another in a patchwork-styles of plateau surfaces, steep slopes, and wetland patches. Within each of these units, farmers classify soil types as either puna or suni.
Viral diseases of potato are a group of diseases caused by different types of Viruses that affect potato crops worldwide and, although they do not affect human or animal health since they are viruses that only infect vegetables, they are a source of great economic losses annually. About 28 viruses have been reported infecting potato crops. However, potato virus X (PVX), potato virus Y (PVY), and potato leafroll virus (PLRV) are the most important viruses worldwide. Some others are of economic importance only in some regions. Such is the case of potato virus M (PVM) in some Asian and European countries.