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 softwooded 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).
Grandiflora's pinnate leaves may be 30 cm long, with 12-20 pairs
of oblong, rounded leaflets averaging 3-4 cm long and about 1 cm wide. The
leaves are borne at the terminals of branches, and the canopy is open, with a
thin crown which produces light shade. Its racemes bear 2-3 flowers. The pods
are usually 30-50 cm long by about 8 mm wide. The seeds are tan to red-brown,
6-8 x 3-5 mm, 14-20 weighing 1 g. The trunk may reach 25 cm diameter at breast
height Grandiflora may live 20 years or more.
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 birnodal rainfall distribution, growing rapidly during wet
seasons but capable of withstanding prolonged dry seasons of up to nine months.
Sesbania grandiflora
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 indicate 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 sources of
food. The young, tender pods are cooked similarly as the green beans. In South
Asia the young leaves are chopped and sauteed, 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.
Financial support for this NFT Highlight was provided by the
Rockefeller Brothers Fund through the Southeast Asia NGO Support Program.
A Publication of the Nitrogen Fixing Tree Association c/o
Winrock International Rt.3,Box 376 Morrilton, Arkansas 72110 USA Tel:
501-727-5435; Fax: 501-727-5417
NFTA 90-03 July
1990
