User:Retomax: Difference between revisions
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===About me=== |
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Reto Flückiger is a Biologist absolving, as a further education, a Master course in Agricultural Science. In this aim he is involved in a lecture about the improvement of Wikipedia-Entries on selected Alternative Crops. |
Reto Flückiger is a Biologist absolving, as a further education, a Master course in Agricultural Science. In this aim he is involved in a lecture about the improvement of Wikipedia-Entries on selected Alternative Crops. |
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= '''''Oxalis tuberosa''''' = |
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==Edibility== |
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Oca are fairly high in [[oxalates]], concentrated in the skin,<ref>Albihn, P. B. E.; and Savage, G. P. (2001). "The effect of cooking on the location and concentration of oxalate in three cultivars of New Zealand-grown oca (''Oxalis tuberosa'' Mol)". ''J. of the Science of Food and Agr''. 81: 1027-1033.</ref> and traditional Andean preparation methods were geared towards reducing the oxalate level of the harvested vegetable. This is done by exposure to sunlight which decreases the organic acid content and so increases the sweet taste of the oca. A scientific study concluded that the bioavailability of oxalate appears to be similar to spinach <ref> The Bioavailability of Oxalate from Oca (Oxalis tuberosa) [http://linkinghub.elsevier.com/retrieve/pii/S0022534705659563] </ref> Recent oca [[cultivars]] have a lower oxalate content, and have also been selected for more flexibility in day lengths.{{Citation needed|date=January 2010}} Comment: Moved from Cultivation to the chapter: Edibility |
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[[Image:Oca.jpg|right|thumb|Pink Oxalis tuberosa (oca) tubers]] |
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{| style="border-collapse:collapse; float:right; clear:right; font-size: 80%" border="1" cellpadding="4" |
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|+ '''Nutritional value per 100 g''' |
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|- bgcolor = lightgrey |
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! |
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| '''fresh''' |
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| '''dried''' |
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|- |
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![[Energy]] (J) |
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|255 |
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|1360 |
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|- |
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![[Water]] (g) |
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|84.1 |
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|15.3 |
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|- |
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![[Protein]] (g) |
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|1.0 |
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|4.3 |
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|- |
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![[Carbohydrates]] (g) |
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|13.3 |
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|75.4 |
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|- |
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![[Ash]] (g) |
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|1.0 |
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|3.9 |
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|- |
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![[Calcium]] (mg) |
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|2 |
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|52 |
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|- |
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![[Phosphorous]] (mg) |
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|36 |
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|171 |
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|- |
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![[Iron]] (mg) |
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|1.6 |
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|9.9 |
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|- |
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![[Retinol]] (µg) |
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|1 |
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|0 |
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|- |
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![[Riboflavin]] (mg) |
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|0.13 |
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|0.08 |
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|- |
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![[Niacin]] (mg) |
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|0.43 |
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|0.85 |
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|- |
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![[Vitamin C]] (mg) |
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|38.4 |
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|2.4 |
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|} |
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== Cultivation== |
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Oca is one of the important staple crops of the [[Andes Mountains|Andean highlands]], second only to the [[potato]] due to its easy propagation, and tolerance for poor soil, high altitude and harsh climates <ref name="Lost">National Research Council. (1989). Lost Crops of the Incas: Little-Known Plants of the Andes with Promise for Worldwide Cultivation. National Academy Press, Washington, D.C.</ref> |
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===Distribution=== |
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===Propagation=== |
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Oca can be propagated vegetativly by planting of whole tubers, which is the usual propagation method, by aerialis stems which is sometimes applied or by seed propagation which is never used.<ref name="Lost" /> |
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===Climate requirements=== |
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Oca need a long [[growing season]], and are [[day length dependent]], forming tubers when the day length shortens in the autumn. In areas with harsh winter climates, early frosts may cut back the foliage before the tubers have a chance to form. In tropical areas where the days are unchanging in length, oca will not set a crop successfully.{{Citation needed|date=January 2010}} |
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===Soil requirements=== |
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the Oca plant generally growth on plots of marginal soil quality and tolerates acidities between about pH 5.3 and 7.8. the crop is grown with very low production inputs and generally on plots of marginal soil quality<ref name="Lost" /> |
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===Cropping factors=== |
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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 (Rea 1975).. Monoculture predominates, but interplanting of several tuber species in one field is in Andean producto common. In many instances Andean farmers will allow a mixture containing two or three tuber crops to be planted in one field. Often this mixture consists of several different clones of each species. Such mixed fields may later be sorted into tuber types during harvest or before cooking. Mixed planting with legumes or grain crops is occasionally practiced.<ref name="Lost" /> |
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===Pest and Deaseas=== |
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Crops in the Andes are usually 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. Cultivation is also constrained by the oca weevil (Ariodistus tuberculatus), Andean potato weevil (Premnotrypes spp) and the ulluco weevil (Cylydrorhinus spp), beetles often destroying entire crops. Further notable pests are nematodes.<ref name="Lost" /> |
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===Yields=== |
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Yields vary with the cultural method. Annals from Andean countries report about 7-10 tons per hectare for Oxalis tuberosa production But with adequate inputs and virus free propagation material, oca production can range from 35 to 55 tons per hectare (http://www.cipotato.org/artc/oca.asp).<ref>Sperling, C.R.; and King, S.R. (1990). "Advances in new crops: Worldwide potential.". ''J. Janick and J.E. Simon (eds.). Advances in new crops. Timber Press, Portland, OR''. p. 428-435.</ref> <ref name="Lost" /> |
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===Agricultural potential=== |
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===Limitations=== |
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As already mentioned can virusis, daylengt restrictions and the precence of oxalates be concidered as limitation factors. Scientists work with specific breeding, selection and virus cleaning programs on these porposes <ref name="Lost" /> |
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== References == |
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{{commons|Carissa macrocarpa}} |
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{{Reflist}} |
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Revision as of 11:42, 14 April 2011
About me
Reto Flückiger is a Biologist absolving, as a further education, a Master course in Agricultural Science. In this aim he is involved in a lecture about the improvement of Wikipedia-Entries on selected Alternative Crops.
Oxalis tuberosa
Edibility
Oca are fairly high in oxalates, concentrated in the skin,[1] and traditional Andean preparation methods were geared towards reducing the oxalate level of the harvested vegetable. This is done by exposure to sunlight which decreases the organic acid content and so increases the sweet taste of the oca. A scientific study concluded that the bioavailability of oxalate appears to be similar to spinach [2] Recent oca cultivars have a lower oxalate content, and have also been selected for more flexibility in day lengths.[citation needed] Comment: Moved from Cultivation to the chapter: Edibility
| fresh | dried | |
| Energy (J) | 255 | 1360 |
| 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 |
| Phosphorous (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 |
Cultivation
Oca is one of the important staple crops of the Andean highlands, second only to the potato due to its easy propagation, and tolerance for poor soil, high altitude and harsh climates [3]
Distribution
Propagation
Oca can be propagated vegetativly by planting of whole tubers, which is the usual propagation method, by aerialis stems which is sometimes applied or by seed propagation which is never used.[3]
Climate requirements
Oca need a long growing season, and are day length dependent, forming tubers when the day length shortens in the autumn. In areas with harsh winter climates, early frosts may cut back the foliage before the tubers have a chance to form. In tropical areas where the days are unchanging in length, oca will not set a crop successfully.[citation needed]
Soil requirements
the Oca plant generally growth on plots of marginal soil quality and tolerates acidities between about pH 5.3 and 7.8. the crop is grown with very low production inputs and generally on plots of marginal soil quality[3]
Cropping factors
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 (Rea 1975).. Monoculture predominates, but interplanting of several tuber species in one field is in Andean producto common. In many instances Andean farmers will allow a mixture containing two or three tuber crops to be planted in one field. Often this mixture consists of several different clones of each species. Such mixed fields may later be sorted into tuber types during harvest or before cooking. Mixed planting with legumes or grain crops is occasionally practiced.[3]
Pest and Deaseas
Crops in the Andes are usually 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. Cultivation is also constrained by the oca weevil (Ariodistus tuberculatus), Andean potato weevil (Premnotrypes spp) and the ulluco weevil (Cylydrorhinus spp), beetles often destroying entire crops. Further notable pests are nematodes.[3]
Yields
Yields vary with the cultural method. Annals from Andean countries report about 7-10 tons per hectare for Oxalis tuberosa production But with adequate inputs and virus free propagation material, oca production can range from 35 to 55 tons per hectare (http://www.cipotato.org/artc/oca.asp).[4] [3]
Agricultural potential
Limitations
As already mentioned can virusis, daylengt restrictions and the precence of oxalates be concidered as limitation factors. Scientists work with specific breeding, selection and virus cleaning programs on these porposes [3]
References
- ^ Albihn, P. B. E.; and Savage, G. P. (2001). "The effect of cooking on the location and concentration of oxalate in three cultivars of New Zealand-grown oca (Oxalis tuberosa Mol)". J. of the Science of Food and Agr. 81: 1027-1033.
- ^ The Bioavailability of Oxalate from Oca (Oxalis tuberosa) [1]
- ^ a b c d e f g National Research Council. (1989). Lost Crops of the Incas: Little-Known Plants of the Andes with Promise for Worldwide Cultivation. National Academy Press, Washington, D.C.
- ^ Sperling, C.R.; and King, S.R. (1990). "Advances in new crops: Worldwide potential.". J. Janick and J.E. Simon (eds.). Advances in new crops. Timber Press, Portland, OR. p. 428-435.