Unlock the potential of Leucaena with our comprehensive guide. Learn about its benefits, uses, and how to incorporate it into your daily life.Leucaena leucocephala . Tree species belonging to the Leguminosae or Fabaceae family.
Leucaena is a genus of about 24 species of trees and shrubs, distributed from Texas , USA to Peru , Paraguay . Some spp. (such as Leucaena leucocephala) have edible fruits and seeds, used in animal feed, green manure, soil conservation, seeds for necklaces, plant source of fuel oil for energy (1 million barrels of oil/year (on 120 km²), anthelmintic in Sumatra and Indonesia .
Botanical characteristics
It is described as a tree that can reach up to 20 m in height with pubescent, petiolate branches, 3 to 6 cm long, with or without glands and upper pinnae a little shorter than the lower ones. Uniquilate leaflets, white flowers in globular, axillary or terminal, pedudunculate heads, mostly agglomerated, 1.5 to 3 cm in diameter. Legumes numerous, linear, flattened, membranous. Seeds ovate, flat transverse.
Within Mimosoideae, together with Lysiloma, Desmanthus, Calliandra and Albizia, it differs from Acacia, Prosopis, Dichrostachys and Pithecellobium, in not having thorns.
Adaptation
It adapts to environments with rainfall from 700.0 to 3 000.0 mm. It does not tolerate prolonged waterlogging. It prefers deep soils with good internal drainage and a pH between 6.0 and 7.5. It tolerates low levels of P. It adapts to clayey, heavy and saline soils.
Toxicity
The leaves and seeds of L. leucocephala contain a non-protein amino acid called mimosine, which is found in 3-5% of the DM of the leaves and is the main cause of the symptoms of poisoning that animals present when they consume them in large quantities.
In laboratory animals (not ruminants) symptoms of hair loss, abortion, infertility, loss of health, decreased milk secretion, deformities and other abnormalities have been found. However, in ruminants, these symptoms are not generally found, due to the transformation that mimosine undergoes by rumen bacteria into 3-4 dihydroxypyridine (DHP), a compound that has a potent goitrogenic effect.
The studies carried out show that when ruminant diets contain less than 30% Leucaena, animals can consume them for long periods, but when this forms more than 50% of the ration, symptoms of poisoning can occur when consumed for periods longer than six months.
The symptoms that appear in poisoned animals are: decreased weight gain, excessive salivation, hair loss and enlarged and enlarged thyroids. In these studies it was observed that the animals affected by goiter did not die and the toxic effect produced by Leucaena is reversible if the animals are changed from this pasture.
It has also been observed that exposure to temperatures of 70°C reduces the mimosine content or by adding ferrous sulphate to rations containing Leucaena not exposed to the sun, toxicity can be reduced.
Establishment and sowing method
Seed treatment
The process of scarifying the seed with hot water at 80º C for 2 or 3 minutes if they are old seeds that have been harvested for a long time, or soaking them in water at room temperature for 24 hours if they are young or recently harvested. Also the inoculation of the leucaena seeds with specific strains of Rhizobium and sowing when there is moisture in the soil , contribute to achieving greater germination and growth of the plants. In addition to the above, animals must remain in the areas until the very moment of sowing, in order to keep the grass as low as possible.
Regulations for sowing
The sowing orientation will be carried out according to the path of the sun (from east to west ) in order to avoid excessive shade in the rows. This is excepted in the case of very steep slopes where it will be done by contour to avoid soil erosion.
Sowing can be done in a light stream (less than 1 kg of seed/ha) or by placing 5 or 6 seeds at a distance of 1 m between them and covering them with no more than 1 cm of soil.
The sowing density should range between 1000 and 3000 plants/ha with a distance of 5 to 6 m between the rows or rows. Cleaning is a task that guarantees the survival and establishment of tree plants. The slow growth of the seedlings makes them vulnerable to predation by the leafhopper ( Atta insulares ), crickets and other insects, and to competition with weeds and the accompanying herbaceous layer, which is why clearing in strips is absolutely necessary until the trees reach a height that exceeds the herbaceous layer by several centimetres.
L. leucocephala cv. Cunningham
Seed production and quality
Pruned annually or every two years ( March ), it produces 356.0 kg total seeds/ha (1st year) and 1 860 kg total seeds/ha (2nd year) with 98.0% purity. The best distance for this purpose is 6.0 m between rows and 3.0 m between plants (550 trees/ha). It produces seed at the beginning and at the end of the rainy season. The freshly harvested seed shows up to 80.0% dormancy.
Scarification with hot water at 80ºC for two to six minutes increases germination from 20.0 to 94.6%. Bacterial gummosis ( Erwinia sp.) can cause losses of between 17.0 and 49.0% of seed production.
Establishment
Sown at the beginning of the rainy season ( April – June ) at depths of 2.0 to 4.0 cm (three seeds per seedling), it reaches its maximum germination peak between 20 and 30 days after sowing. It grows slowly in the first 65 days (1.0 cm/day), so cultivation of the ring is required.
After one year of sowing, it reaches a height of 1.50 m, with 15 to 20 branches/plant. In pure cultivation it should be sown in 3.0 x 1.0 m frames and in association with 3.0 x 3.0 m frames. In areas where mechanisation is difficult, transplanting in bags should be used, with 45.0 to 60.0 cm seedlings. It does not nodulate well with native rhizobia, so specific strains such as IH-016; IH-024 and CB-81 are recommended. It can fix up to 500.0 kg of N/ha/year.
Performance and chemical composition
Whole plant yields can be 14.2–18.0 t DM/ha/year under irrigation and 7.0–14.0 t DM/ha/year under rainfed conditions. Dry matter, crude protein, crude fiber, calcium , and phosphorus contents range from 20.0–32.0; 18.0–27.0; 27.0–34.0; 1.18–2.43; and 0.27–0.35%, respectively.