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Pachyrhizus ahipa, also called the ahipa or Andean yam bean, is a tuberous root-producing legume, which is mainly distributed in the Andean region. History Archaeological evidence suggests P. ahipa was widely distributed about 2000 years ago. The first mention of ahipa was in connection with the Indian cultures in the Andes, more precisely in the Salta and Jujuy provinces of Argentina. Indications of the Pachyrhizus species in general were also made at the southern coast of Peru, in the Nasca culture. The origin of the ahipa plants is most likely in the ceja de montañas Andean region. Today, it is still in use in small native communities in Bolivia and northern Argentina. The crop was never widely distributed which could have to do with the very specific climatic adaptions it exhibits. Another reason could be the acquisition of Latin America by the Spanish and Portuguese conquest, which had the general policy to destroy the traditional Andean agricultural systems. The local marketing of the Andean bean during the religious festival Corpus Christi indicates a relationship with ancient religious uses. Today, the production is restricted to a few local villages and farmers. Description Pachyrhizus ahipa is member of the Fabaceae and predominantly self-pollinating. The Andean bean is a perennial plant and can grow in erect, semierect or twining forms. The erect species can grow to 15–40 cm tall, the semierect one about 30–60 cm, and the twining forms 60–200 cm long. These plants are herbaceous and lignified depending on the genotype. They do not show a lateral axis. The leaves are trifoliate with stipules or pinnately arranged leaflets with caduceus stipels. The flowers, which grow on short stalks, are white blossoms or of a pale lavender colour. They show a tubular calyx and a papilionaceous corolla. Generally, the flowers exhibit an internally curved stigma in close contact with the anthers. This habitus is very unfavourable in connection with the pollination behaviour of insects, as they are not able to pollinate the flowers very effectively. Additionally, the pollen fertility is often not very high. It varies between 45 and 100%. The flowering pattern is not consistent. Each season, 100 – 800 flowers per plant can be produced. P. ahipa is a short-day plant, so flowering takes place under decreasing day length. The pods are 13–17 cm long and up to 16 mm wide. The seeds are black, lilac, maroon, or black and white mottled. They are round, kidney-shaped, and about 0.8–1 cm long. Seed production differs from plant to plant and lies between 20 and 100 per plant. The thousand grain weight is around 300 g. Every plant shows a single swollen root, which thins out toward both ends. The roots are about 15 cm long and usually weight about 500–800 g. The yellow skin of the root encloses a white pulp, which is interwoven with a soft fiber. Culture Sowing Before sowing, the soil must be loosened to a depth of 15–25 cm. Further, the soil has to be thoroughly cleaned from weeds and stones. In Bolivia, P. ahipa is normally sown between August and October, depending on the rainy season. The seeding rate is between 40 and 65 kg/ha. In determining the rate, preferred traits such as tuber size play an important role. Further, soil fertility and seed weight must be taken into account. The planting distance is 20–60 cm between rows and 6–25 cm between plants in the same row. Therefore, about six to 83 plants/m2 are possible. It is planted on ridges, when it is flood irrigated, which is mostly the case in the Andean region. Cultivation The cultivation period is between five and 10 months. The first flowers appear 87–140 days after sowing. Those flowers are removed manually, a process called reproductive pruning. This means the flowers, as well as the young pods, are removed. The tuberous roots remain the main sink for photosynthates and nutrients. The yield improves drastically. Reproductive pruning is very labour-intensive and must be done once or twice a season. Mature pods normally appear from April through June. At about nine months, the roots are tuberized and the aerial part is completely dry. P. ahipa is normally sown in a pure culture, but can be intercropped with maize. In a crop rotation, it is sown prior to maize/potato, maize/tomato, maize/oca, groundnut or manioc. Environmental conditions Pachyrhizus ahipa can mainly be found in cool tropical and subtropical valleys, on sun-facing slopes, on the border between the warm and cold tropics. The average temperature in this region is 16–18 °C, although the climatic conditions are extremely dependent on the time of day. The precipitation is between 400 and 700 mm, occurring within 4–6 months, with the rest being the dry season. Therefore, the climate is semiarid. P. ahipa grows to an elevation of 1800 – 3000 m above sea level. Cultivation is mainly carried out along loamy riverbanks. It can also be grown on loamy hillsides. It favours soil pH levels of 6–8 and well-drained soil types. Pachyrhizus ahipa plants can tolerate long dry spells. However, to increase tuber yield, more water is essential. Nutrient needs At the time of harvest, seeds show high nitrogen contents, but some remains in leaves, providing a nitrogen-rich straw which can be used for animal feeding or as fertilizer, if the plant material is incorporated into the soil. In one season, 67 kg N/ha were taken up by roots and seeds. This nitrogen is mainly provided by the inoculation with efficient bacterial strains. The P. ahipa plant is therefore able to form an efficient symbiosis with nitrogen-fixing bacteria, such as Rhizobium and Bradyrhizobium, and is able to fix 58–80 kg nitrogen per hectare. No further supply of nitrogen fertilizer is needed. If the vegetative aboveground parts are left in the field, a substantial amount of the fixed nitrogen is returned to the soil, about 12–80 kg N/ha. The enrichment is very important if a sustainable land-use system is desired. During nodulation, an increased phosphorus supply is advantageous, because nodulation can be improved. Further, it promotes the root and seed yield in P. ahipa plants. The final recipients of P are the pod shells, as well as the seeds. In total, about 7–9.6 kg P/ha were extracted from the soil. At harvest, the highest potassium contents can be found in pod shells and the roots. The removal of K at harvest was about 20.2 kg K/ha. Disease Pachyrhizus ahipa plants are not very susceptible to pests. Nematodes such as Meloidogyne sp. can pose a serious problem. Further, some of the bean weevil species can be harmful. The most serious viral disease is the bean common mosaic virus (BCMV). Yields can be reduced up to 30% if infected by this virus. If a general irrigation management is lacking, rot is also likely to appear. Harvest The tubers of P. ahipa are harvested as soon as the tubers show a marketable weight, depending on consumer’s preferences. Mostly the preferred weight is minimally about .... Discover the Christi Doporto popular books. Find the top 100 most popular Christi Doporto books.