June 1994 NFTA 94-05
A quick guide to useful nitrogen fixing trees from around the world
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NFT Highlights
June 1994 NFTA 94-05 A quick guide to useful nitrogen fixing trees from around the world |
Sesbania grandiflora: NFT for beauty, food, fodder and soil improvement
Sesbania grandiflora is a tree that grows rapidly, provides light shade, and is often grown as an ornamental. This soft-wooded tree's leaves are used as fodder and its flowers as food. Grandiflora is planted in gardens for its intercropping compatibility and soil-improving properties.
| Botany
Sesbania grandiflora (L.) Poir. is a tree that grows to 8-10
m in height. The pink-red or white flowers of this papilionaceous (pea-like
flowered) legume are unusually large (5-10 cm in length and about 3 cm
wide before opening); this novelty may be the principal reason for grandiflora
having been distributed by man throughout the tropics and subtropics. Within
its genus, S. grandiflora is a member of the subgenus Agati, and
it is thus more closely related to the unusual littoral sesbanias of Pacific
islands than to the more typical sesbanias of subgenus Sesbania, such as
the perennial S. sesban and the annual sesbanias grown for green
manure (such as S. cannabina).
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Grandiflora is very closely related to the endemic Australian species, S. formosa. This relationship supports the supposition that grandiflora may have originated in Indonesia. S. formosa bears white flowers and is often indistinguishable from grandiflora to the casual observer. The two species appear to have similar growth habits and adaptivity, and it is possible that S. formosa also can be used for the purposes described here for grandiflora.
Distribution
Grandiflora is found in cultivation throughout the tropics and subtropics.
Ecology
Because wild populations of grandiflora are unknown, its natural habitat is uncertain. Grandiflora is grown most successfully in the lowland tropics (below 1000 m elevation) and warm, frost-free subtropics. It can be grown in regions with as little as 800 mm rainfall or as much as 2000-4000 mm. It seems to prefer a bimodal rainfall distribution, growing rapidly during wet seasons but capable of withstanding prolonged dry seasons of up to nine months. Grandiflora is tolerant of soil salinity and waterlogging, and withstands occasional short periods of flooding. It is well adapted to heavy clay soils.
Uses
Fodder, food, and soil improvement are the principal uses for grandiflora.
Fodder. Grandiflora is valued as a fodder in many regions. In
south-central Lombok, Indonesia, grandiflora grown around rice paddy bunds
provides up to 70 percent of the diets of cattle and goats during the annual
eight-month dry season (Mudahan Hazdi, personal communication). The leaves
contain as much as 25-30 percent crude protein.
Although ruminants readily consume grandiflora fodder, and its
digestibility is high, some feeding studies have indicated that antinutritional
factors are present. Until further research provides clear guidelines,
caution should be used in feeding S. grandiflora to ruminants and
other animals, and restricting feeding to less than 30 percent of dry matter
intake is suggested. Grandiflora leaf is toxic to chickens and should not
be fed to them or other monogastric animals.
Soil improvement. Grandiflora is often maintained in gardens and around crop fields for its contribution of nitrogen. The light shade cast by its canopy does not block much light, allowing the growth of companion plants. Falling leaflets and flowers recycle nutrients to the ground. Seedlings grow rapidly enough that they have been used similarly to annual green manure crops. For example, grown around paddy bunds for incorporation before planting the subsequent rice crop.
Wood. The wood is rather light and not ideal for firewood or pulping; the bark is thick and corky and is a further detriment to either of these uses. The trunks may be used as poles for temporary shelters and sheds, but they may not last very long due to rots and insect infestation.
Food. Leaves, seed pods, and flowers of grandiflora are prepared as food. The young, tender pods are cooked similarly to other green beans. In South Asia the young leaves are chopped and sautéed, perhaps with spices, onion, or coconut milk. In the Philippines, unopened white flowers are a common vegetable, steamed or cooked in soups and stews after the stamen and calyx have been removed. Selection of white-flowered varieties that flower profusely has resulted from this use in the Philippines.
Other uses. Grandiflora has been used to shade nurseries and some crops, such as turmeric, as support for climbing crops such as pepper and betel vine, and as an element of windbreaks. The leaves of the tree have various uses in the herbal medical lore of certain regions.
Culture and Management. Grandiflora is grown from seed, which
may be planted without scarification. Stored seeds lose viability within
a year or two. Seeds may be direct-sown or transplanted from nurseries;
bare-rooted transplants are usually successful.
Seedling growth of grandiflora may be very rapid. Under harsh
conditions or neglect, however, seedling survival may be poor. The leaf
canopy is open and casts only light shade, hence its popularity in gardens.
Grandiflora cannot be coppiced or pollarded. Harvesting leaves
for fodder must be done selectively, to avoid complete defoliation, and
cannot be done more than a few times per year. More intensive harvesting,
such as managing as a hedgerow, reduces the life of the tree. For example,
cutting at 1 m high five times a year can result in tree mortality. Because
grandiflora establishes so rapidly, frequent replanting is a management
option if heavy harvesting results in tree decline.
Where flowers and pods are harvested for consumption as vegetables,
the structure of the tree is shaped by pruning so that the canopy remains
low, within reach for convenient harvesting.
Symbiosis
The rhizobia strains that nodulate sesbanias are somewhat specialized and may not be present where sesbanias have not been grown previously. Test plantings should be done to see if infective rhizobia are present in the soil, or if use of a rhizobia seed inoculant at planting will be necessary.
Limitations
Grandiflora's soft wood is susceptible to damage by insects. Fodder cuttings cannot be severe. Seed recovery may be limited by pod pests. Seed viability declines after one year.
References
Evans, Dale O. 1990. What is Sesbania? Botany, taxonomy, plant
geography ,and natural history of the perennial members of the genus. In:
B. Macklin and D.O. Evans (eds), Perennial Sesbania species in agroforestry
systems. Nitrogen Fixing Tree Association. p. 5-19.
Evans, D.O., and Macklin, B. (eds). 1990. Perennial Sesbania production
and use. Nitrogen Fixing Tree Association. 41 p.
Evans, D.O., and Rotar, P.P. 1987. Sesbania in agriculture.
Westview Press, Boulder, Colorado, U.S.A.
This issue was prepared by Dale O. Evans, Research Associate, Department of Horticulture, University of Hawaii, 3190 Maile Way, Honolulu, Hawaii 96822, USA.
A publication of the Forest, Farm, and Community Tree Network (FACT Net)
Winrock International
38 Winrock Drive
Morrilton, Arkansas 72110-9370 USA
Tel: 501-727-5435
Fax: 501-727-5417
Email: forestry@winrock.org
www.winrock.org/forestry/factnet.htm
Financial support for this NFT Highlight was provided by the Rockefeller Brothers Fund through the Southeast Asia NGO Support Program.