Erythrina edulis

Erythrina edulis
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fabales
Family:	Fabaceae
Genus:	Erythrina
Species:	E. edulis
Binomial name
Erythrina edulis

'Basul' (Erythrina edulis) is a nitrogen fixing leafy tree that is native in Andean region from western Venezuela to southern Bolivia. Nowadays it is known in Venezuela as “Frijol mompás”, in Bolivia, Peru and Argentina as “Pajuro”, “Sachaporoto del basul” or “Poroto del sacha”, in Colombia as “Chachafruto”, “Balú”, “Baluy” or “Sachaporoto” and as “Guato” in Ecuador. Although it is widely known, it’s still poorly cultivated. Future research is needed, especially in agroforestry.^[1] Besides the agricultural aspects, Erythrina edulis can also be used as a fence plant.^[2] Basul is a legume and so it produces protein-rich beans covered in pods which can be used for human or animal nutrition. The leaves and branches can also be used but only as fodder source.

Cultivation

Erythrina edulis is a vigorous, fast-growing precocious legume species that is known as the one of the easiest trees to grow. As it is sensitive to the cold, it grows only in the tropics in Africa, Asia and Latin America. Due to its temperature requirements (optimum between 15 and 22 °C)^[3] it is not suitable in Europe, North America and other temperate regions although it battens in a broad range of height (from 900-3200 a.s.l.). In their original habitat, the annual precipitation varies between 450 and 1800 mm.^[1]Erythrina edulis grows best in well-drained soils with a sandy or clayey texture and a pH range from 5.5 to 7.^[3] Erythrina edulis is a totipotent plant and thus propagates easily. Hence, stems can be cut, planted into the soil and will sprout. Propagation can also be achieved by planting mature seeds and in most cases they germinate easily. Grafting is another possibility, the advantage here is that the seed production will start earlier. The seeds must be planted very soon after harvesting because they lose their viability 8 days after harvesting. The viability can be extended to 20 days when the seeds are covered in a thin paraffin layer.^[4] Erythrina edulis produces red flowers which are formed in a raceme and are cross-pollinated by bees, wasps and birds.^[2] The ripening of the seeds is not synchronized. The harvest and processing is likely to beans. The tree can live for decades and the older it gets, the more grains it will produce. A three- to four-year-old tree can produce about 30 kg grains per year while a 20 year old tree reaches amounts between 120 to 210 kg grains per year.^[5] Thanks to the symbiosis with Rhizobium bacteria, Erythrina edulis can fix atmospheric nitrogen and therefore does not need any additional nitrogen fertilizer.

Agricultural importance

Erythrina edulis is a suitable crop for agroforestry. Thanks to nitrogen fixation, both crops included in the intercropping system are benefitted from the higher nitrogen content in soil.

Due to ameliorating effects of nitrogen fixation there is an additional chance to make wasteland more productive. In the same time, you can produce food during scarcity because the seeds are normally ripe when last year’s stocks are exhausted but when it’s still too early for the new harvest. The trees can be grown in association with other cash crops as sugar cane, coffee and cacao. A basul tree can grow very high (8–14 m). As it provides shadow, basul tree can serve to protect sun sensitive crops from strong radiation. This association is not only beneficial for the sun sensitive crop but also for basul because they are less harmed by different pests when they grow in association compared to a monoculture.^[5] Furthermore it provides a good alternative to the characteristic starch based diet in developing countries. The amino acid pattern of the seeds of Erythrina edulis forms a good complement to cereals and tubers. Because of the advantages of spatial diversity and the sustainability of agroforestry systems, this form of cultivation gains day after day on importance. Nowadays there is, even in the origin region, still very little known about Erythrina edulis apart from some rural areas of Colombia. Till now combinations with coffee, cacao, pepper, betel and grape were observed.

Basul as a food source

Basul can be used as a food source for humans and animals. The tree carries pods with grains. The length of these pods varies between 15 and 65 cm with an average around 32 cm. The green pods can be eaten, but it is more frequent to eat the mature grains. Every pod contains 6 grains. These grains are 1.4 – 6.4 cm long and have a weight between 15 – 30 g.^[6] The fresh grains have a high water content, around 80%. Due to this water content, the grains cannot be stored very well. On dry matter basis, the grains have a protein content between 18-23%. The protein is composed like protein in most legumes with a high lysine content and lower concentrations in sulfur-containing amino acids (methionine and cysteine) and tryptophan. The grains do not only contain proteins but also high amount of starch (26-40%).^[5] To use the grains in human food, they need to be boiled or fried for at least 45 minutes. If the grains are eaten raw frequently, they can be toxic because they contain some alkaloids.^[4] All the other Erythrina species contain much more alkaloids and are thus much more toxic. Some of these species resemble the Erythrina edulis species,^[7] the difference is clear for a trained eye. If you don’t have a trained eye, then be careful with harvesting and eating the beans. The cooked beans can be used in soups, cakes, salads, tortillas etc. They can be dried after the boiling process, grounded and used as flour with different purposes.^[4] Nowadays the grains are not yet very common. Till now its use is limited to the period when other food supply is scare, but the South-American governments are advertising this bean in the Andes. For example they distribute recipes that people become more aware of this possible food source. Also the Colombian government is trying to conserve these beans in cans with the aim to provide an opportunity to store them longer and to open the export market.^[5] The tree bean is not only useful as a food source for humans but also as a food source for animals. In animal nutrition the leaves, the grains and pods can all be used as fodder. The leaves are only used for animal nutrition due to their high protein content (around 24%). The leaves are rich in potassium and poor in calcium. When the pods and grains are used as fodder for chickens, fish, pigs or rabbits, they need to be boiled first, otherwise they can be toxic because of the alkaloids. The boiling process is not necessary when the pods and grains are fed to goats and cattle.

Future improvements

The tree doesn’t have a particular harvest time. The harvest time is variable for each tree, even if these trees grow on the same location. The grain is often used when other food is scare, for instance during the rainy season. This is good for small farmers which only uses the products from their own farm for feeding the animals and the family but not for breeding. One of the goals is to synchronize the harvest time of all the seeds in one cultivar. Another goal is to find a solution for the storage problem. The seeds can’t be stored due to the high water content, so they can try to find a cultivar with a lower water content in the seeds. Nowadays they are trying to avoid this problem by using the seeds very quick after harvesting in flour. Also the viability of the seeds need to be improved. The Erythrina edulis is not produced on a large scale yet, and probably this will never happen. But the tree is a good alternative for the small farmers because of the different uses (food, fence, fodder,…). Also, in South-America, and as well in the rest of the world, very few crops are cultivated and used as food and fodder sources. The Erythrina edulis can change this and can benefit the biodiversity.

References