Lupinus mutabilis is a species of lupin grown in the Andes, mainly for its edible bean. Vernacular names include tarwi (in Quechua II,
Origin and dissemination
The origin of
L. mutabilis has been identified in the Andean region of Ecuador, Peru, and Bolivia.
[ Neglected crops: 1492 from a different perspective (1994). Ed.: J.E. Hernándo Bermejo and J. León; publ. in collab. with the Botanical Garden of Córdoba (Spain)] In this area, the greatest genetic variability of this species was found. The plant has been domesticated for over 1500 years because of its high protein content.
Biology
L. mutabilis is an annual plant. The stem is hollow and highly branched. Plant height reaches from , depending on the environmental conditions and the genomic properties. Due to the high vegetative growth, species from northern South America are taller than species from the southern Andean region.
Its highly variable genome contains 2n = 48 chromosomes, which leads to significant differences in morphology. Several architectural types of
L. mutabilis exist. The most common is the branching in V-form, which has the highest biomass production. The basal branching type has the positive feature that its infructescence is at the same level. This species is preferably promoted because of its early ripening, stability, and homogeneity in seed quality.
Morphology
The fruit is a long pod, depending on the amount of seed. One pod contains on average 2–3 seeds, but can have up to 9 seeds per pod. The thousand-seed weight (TSW) is around 200 g. Leaves are palmate and have a typical appearance: one leaf is divided into five to twelve leaflets with an oval or lanceolate form. The form is typical for
. The corolla reaches and contains five petals. Variation in coloration is high and reaches from white to purple. The white coloration is recessive to purple.
L. mutabilis has a strong taproot reaching length. Like all Leguminosae, secondary roots build nodules containing bacteria for nitrogen fixation.
Development
The growing cycle varies from 150 to 360 days, depending on the genotype, altitude, and environmental conditions. Phenological phases are emergence, first true leaf, formation of the raceme on the central stem, flowering, podding, pod ripening, and physiological maturity.
Use
Human consumption
The bone-white seed contains more than 40% protein and 20%
fat and has been used as a food by Andean people since ancient times, especially in
,
,
and by itself mixed with boiled
maize. Like other legumes, its protein is rich in the essential amino acid
lysine. The distribution of essential fatty acids is about 28%
linoleic acid (omega-6) and 2%
linolenic acid (omega-3). It has a soft
seed coat for easy cooking. It may not have been more widely used because of its bitter taste due to the
alkaloid content. It contains unusually high amounts of
sparteine, which make up nearly half of its alkaloid content. However, the alkaloids are water-soluble and can be removed by soaking the seeds in water for a few days.
QAs are heat-stable toxins; cooking alone does not remove the alkaloids.
Like other species of
, chocho beans are expanding in use as a plant-based protein source in the world marketplace.
Chemical composition
L. mutabilis contains 42% protein and 18% fat on average (Table 1).
The high fat content has allowed commercial oil pressing. The protein digestibility and nutritional value are similar to those in
.
Table 1. Chemical composition of the tarwi seed:[ 2.1.2. Composición química y valor nutricional de Lupinus mutabilis]
|
|
| 37.7 – 49.7 |
| 12.8 – 22.2 |
| 4.29 – 7.51 |
| 3.10 – 4.24 |
| 23.7 – 29.9 |
| 2.56 – 4.14 |
The oil content ranges from 13 to 19% (w/w) (Table 2). Interestingly, oils extracted with ethanol contain higher levels of antioxidants, phenolic compounds, and polar lipids associated with health benefits.
Table 2. Fatty acid composition of tarwi seed.
|
| C14:0 (myristic acid) | 0.13 ± 0.04 | 0.12 ± 0.01 | 0.13 ± 0.03 |
| C16:0 (palmitic acid) | 8.43 ± 0.11 | 8.69 ± 0.68 | 8.57 ± 0.52 |
| C16:1 (palmitoleic acid) | 0.20 ± 0.03 | 0.21 ± 0.02 | 0.21 ± 0.01 |
| C18:0 (stearic acid) | 5.17 ± 0.11 | 5.59 ± 0.37 | 4.75 ± 0.11 |
| C18:1-n9 (oleic acid) | 62.49 ± 0.80 | 55.02 ± 1.31 * | 62.03 ± 1.60 |
| C18:2-n6 (linoleic acid) | 21.57 ± 0.35 | 28.15 ± 1.64 * | 21.79 ± 1.33 |
| C18:3-n3 (α-linolenic acid) | 1.04 ± 0.07 | 1.11 ± 0.08 | 1.42± 0.18 |
| C21:0 (henicosanoic acid) | 0.96 ± 0.03 | 0.79 ± 0.17 | 0.89 ± 0.05 |
| C20:1-n9 (cis-11-eicosenoic acid) | ND | 0.10 ± 0.80 | 0.11 ± 0.01 |
| C23:0 (tricosanoic acid) | ND | 0.22 ± 0.70 | ND |
| C22:1-n9 (erucic acid) | ND | ND | 0.11 ± 0.01 |
| Total number of fatty acids extracted | 8 | 10 | 10 |
ND = not detected. * Values in the same row differ significantly (p < 0.05).
As with all Lupinus spp., L. mutabilis produces compounds called (BLADs). Also, as with the rest of the genus, it produces called BLAD-containing oligomers (BCOs). BCOs have a fungicide action[ p.16]
Wild populations of L. mutabilis contain toxic, bitter quinolizidine alkaloids. also contain QAs but at much lower levels thanks to begun in Germany in the 1930s.
Green manure and soil improver
L. mutabilis can fix nitrogen from the air. Therefore, succeeding cultures can profit from of nitrogen per hectare. Incorporation in the flowering stage leads to a higher quantity of organic matter and an improved soil structure.
Agricultural aspects
Soil and climate requirements
L. mutabilis is a crop for cool climates and exists mainly in valleys at high altitudes, such as the Andes at tropical latitudes. The crop can be grown at an altitude that ranges from . The crop withstands exceptional levels of drought. Mature plants are resistant to frost, whereas seedlings are sensitive to low temperatures.
Cultivation technique
Sowing
In traditional farming practices, minimum tilling is done before sowing. of unselected seeds is sown.
Improved cultivation practices:
It is recommended to apply phosphorus and of potassium as fertilization before sowing. The sowing of selected seeds in a distance of , either by hand or by seed drill, follows. Plants germinate fast due to the high-fat content in the seeds.
Crop rotation aspects
Early varieties of L. mutabilis, with a growing period of about 150 days, can be cultivated in rotation with potatoes and cereals. Nematode disease of potato can be controlled by alkaloids when cultivated after L. mutabilis.
Harvest
In traditional farming practices, harvest occurs when plants have reached full maturity and the water content of seeds is between 8-12%.
Disease control
Alkaloids can act as pesticides, but breeding goals aim to achieve a low alkaloid content.
Breeding goals
Since species with low alkaloid content are already available,
a further step would be to make them more stable, and low alkaloid content is inherited. Other breeding goals are tolerance to diseases and insects, improvement in yield, early maturing, and synchronous ripening. Higher resistance could be reached by breeding a variety with high alkaloid content in leaves but not in the seeds.
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