Sesbania grandiflora (L.) Poir.
Author: J.M. Suttie
Agati, Brède Malabar (Mascareignes)
The exact origin of S. grandiflora is not known but it is considered native to many southeast Asian countries. Until recently, the use of perennial Sesbania species has largely been restricted to south and southeast Asia. Most of the early research on the use of perennial Sesbania for forage production was conducted in India (Patel 1966, Kareem and Sundararaj 1967).
In India, sesbanias have had a long history of agricultural use, primarily as green manures and as sources of forage. The wood of S. grandiflora, on the other hand, is not highly valued for cooking as it has poor burning qualities and produces much smoke. The density of its wood increases with ageing and the timber from 5-8 year old trees can be used in house construction or as craftwood. The flowers and young leaves of S. grandiflora are edible and are often used to supplement meals (Gutteridge and Shelton 1998) Tender pods may also be eaten as vegetables. The dried leaves of both S. grandiflora and S. sesban are used in some countries as a tea which is considered to have antibiotic, anti-helminthic, anti-tumour and contraceptive properties.
Sesbania grandiflora was declared inappropriate for alley cropping in the lowland humid tropics of Nigeria because it showed a high mortality of up to 80% when coppiced.
Sesbania grandiflora is a loosely branching tree up to 15 m tall. Its leaves are pinnately compound up to 30 cm long with 20-50 leaflets in pairs, dimensions 12-44 x 5-15 mm, oblong to elliptical in shape. Flowers are large, white, yellowish, rose pink or red with a calyx 15-22 mm long. The standard has dimensions up to 10.5 x 6 cm. Pods are long (20-60 cm) and thin (6-9 mm) with broad sutures containing 15-50 seeds.
It is well adapted to hot, humid environments and does not grow well in the subtropics particularly in areas with cool season minimum temperatures below about 10°C.
It is outstanding in its ability to tolerate waterlogging and is ideally suited to seasonally waterlogged or flooded environments. When flooded, they initiate floating adventitious roots and protect their stems, roots and nodules with spongy, aerenchyma tissue. Evans and Macklin (1990) report that S. grandiflora is adapted to rainfall conditions of 2,000-4,000 mm but will grow in areas receiving only 800 mm.
Another outstanding feature is its tolerance of both saline and alkaline soil conditions (Hansen and Munns 1985). However, its tolerance of highly acid, aluminium saturated soils is not known.
It is usually established from seed. Sesbania grandiflora is not hard-seeded and usually germinates well without scarification. It has specific rhizobial affinities so Domergues et al (1999) recommend inoculation with the appropriate strain of Sinorhizobium saheli if native rhizobial populations are inadequate. One of the major advantages of perennial Sesbania species over other forage trees and shrubs is their rapid early growth rates.
S. grandiflora appears to be pollinated by birds (Brewbaker 1990). Seed collection from most of the perennial sesbanias is easy and large quantities of seed can be rapidly hand-harvested and processed.
Crop use and grazing management
Cutting management has a very important influence on the productivity of perennial Sesbania species. Sesbania grandiflora cannot survive repeated cutting (Evans and Rotar 1987) . Farmers in Lombok, Indonesia have devised a system where only the side branches of trees are cut for fodder leaving the main growing stem untouched. The trees are grown on rice paddy walls at 1.5-2 m intervals and forage is harvested in this manner for 3-4 years, yielding up to 2 kg dry matter per harvest per tree. When the foliage is no longer within easy reach the trees are felled and the long straight pole can be used for firewood or for construction. More research is required to determine appropriate management systems to maximize yields of edible material. The trees are grown on rice paddy walls at 1.5-2 m intervals and forage is harvested in this manner for 3-4 years, yielding up to 2 kg dry matter per harvest per tree. When the foliage is no longer within easy reach the trees are felled and the long straight pole can be used for firewood or for construction (Gutteridge 1987).
In northern Thailand, S. grandiflora was an excellent supplement to dairy cows fed predominantly grass hay. Most reports indicate that the crude protein content of S. grandiflora foliage is generally greater than 20% and often above 25%. Dry matter digestibility of Sesbania species is superior to that of most other tree and shrub legumes. In northeast Thailand, Akkasaeng et al. (1989) found that the in vitro dry matter digestibility of S. grandiflora, S. sesban and S. sesban var. nubica was 66, 75 and 66% respectively, all higher than that of 15 other tree legumes that were tested. van Eys et al. (1986) reported that S. grandiflora contained more crude protein but less fibre than Gliricidia sepium and Leucaena leucocephala while their in vitro dry matter digestibilities were 73.3, 65.2 and 62.2% respectively.
It appears that the most economically efficient and safest use of perennial Sesbania forage for ruminants is as a protein supplement to low quality roughages such as crop residues or dried grasses. This dilutes the effects of anti-nutritive factors and greatly improves the utilisation of the roughages.
It appears that the use of the perennial Sesbania species should be restricted to ruminants because of the deleterious effects often observed when they are used as feed sources for monogastrics. However, even with ruminants, there may be adverse effects on animal productivity and health when Sesbania comprises a high proportion of diets for long periods. Research is required to determine whether anti-nutritive factors are present in Sesbania forage and whether they can be controlled or reduced by management practices.
Sesbania grandiflora appears to be relatively pest free.
Akkasaeng, R. et al.(1989); Brewbaker, J.L. (1990); Dommergues, Y. E. et al.(1999); Evans, D.O. and Macklin, B. (1990); Evans, D.O. and Rotar, P.P. (1987);Gutteridge, R.C. (1987); Gutteridge R. C. and M. Shelton (1998); Hansen, E.H. and Munns, D.N. (1985); Kareem, S. and Sundararaj, E.D. (1967); Patel, B.M. (1966) ; van Eys, J.E.et al.(1986);