Sesbania Grandiflora, more commonly known as Agati or Hummingbird tree is a fast growing tree that grows primarily in hot and humid tropical areas of the world.
Common Names
| English |
Agati or Agathi August Flower Hummingbird Tree Sesban |
| Tamil |
அகத்தி
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| Hindi |
गाछ मूंगा
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Taxonomy
| Kingdom |
Plantae – Plants |
| Subkingdom |
Tracheobionta – Vascular plants |
| Superdivision |
Spermatophyta – Seed plants |
| Division |
Magnoliophyta – Flowering plants |
| Class |
Magnoliopsida – Dicotyledons |
| Subclass |
Rosidae |
| Order |
Fabales |
| Family |
Fabaceae – Pea family |
| Subfamily |
Faboideae |
| Genus |
Sesbania |
| Species |
Sesbania grandiflora |
| Synonyms |
Aeschynomene grandiflora, Agati grandiflora, Robinia grandiflora, Sesban grandiflorus |
Geographic Distribution
The exact origin of Agati is not known (India or Indonesia have been suggested), but it is considered native to many Southeast Asian countries. It is widely distributed throughout the tropics, from southern Mexico to South America. It has been cultivated for at least 140 years in West Africa, and more recently in East Africa.
Ecology & Biophysical Limits
Because wild populations of Agati are unknown, its natural habitat is uncertain. Agati is well adapted to hot, humid environments. It is commonly seen growing on rice bunds, along roadsides, in home gardens and in mixed croplands. It is not wind resistant.
Altitude & Temperature
Only adapted to the lowland tropics up to 800 m, occasionally to 1,000 m above sea level environments with mean annual temperatures of 22-30ºC. Agati is frost sensitive and intolerant of extended periods of cool temperatures(below about 10ºC).
Shade Tolerance or Light Requirement
Poor shade tolerance. Its rapid early growth and erect habit usually enables Agati to access sunlight by overtopping neighbouring plants.
Soil Requirements
Agati is tolerant of soil salinity and waterlogging, and withstands occasional short periods of flooding. It is well adapted to heavy clay soils. It is Tolerant of a wide range of soils including soils that are alkaline, poorly drained, saline, or of low fertility. Agati has some tolerance of acid-soils down to pH4.5.
Moisture
Best adapted to regions with annual rainfall of 2,000-4,000 mm, but has been grown successfully in semi-arid areas with 800 mm annual rainfall and up to 9 months dry season. Tolerant of flooding over short periods and is ideally suited to seasonally flooded environments.When flooded, it initiates floating, adventitious roots, and protects their stems. It seems to prefer a bimodal rainfall distribution, growing rapidly during the wet season, but is capable of withstanding prolonged dry seasons of up to 9 months.
Tree Management
Agati establishes rapidly from seed or by vegetative propagation from stem and branch cuttings. It is not hard seeded and usually germinates well without scarification. Scarification may improve uniformity of establishment but is not considered essential. Stored seeds lose viability within a year or two. Seeds can be sown directly into well-worked soil at the beginning of the rainy season. Pretreatment could involve either scratching or nicking the round end of each seed, avoiding the cotyledon, or soaking in cold or tepid water for 24 hours; 85-90% germination occurs. In the nursery, plants can be raised in polythene bags. These plants can be established in the field in 1 month. Agati can also be propagated vegetatively by stem and branch cuttings.
Seedling growth of Agati may be very rapid. Under harsh conditions or neglect, however, seedling survival may be poor. The species is very fast growing, hence does not live long and can be harvested on a 3-year short rotation. The growth rate depends on type of soil, cultural practices and amount of water available, which can be supplemented by irrigation. Agati plantations have reached 3.2 m in 9 months when raised in loamy soils, but only 1.8 m in sandy soils. In well-drained, deep loamy soils, plantations raised at 0.9 x 0.9 m can yield 4 t/ha per year. The height growth is extremely fast in the 1st year; it slows down considerably in the subsequent 1-2 years, but the diameter growth rate does not slow down. The leaf canopy is open and casts only light shade, hence its popularity in gardens.
Agati will not tolerate repeated cutting of the main stem above a certain height. Intensive harvesting, such as managing for a hedgerow, shortens the life of the tree. For example, cutting at 1 m high five times a year can result in tree mortality. A suitable system involves cutting for fodder only the side branches of trees, leaving the main growing stem untouched. Because Agati 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. When the foliage is no longer within easy reach, the trees are felled and the long, straight pole can be used for firewood or construction. Under irrigation it grows well, and when grown in backyards the tree normally grows well as it gets waste water from the kitchen. For fodder production, Agati can be grown individually in gardens, house lots and mixed planting. It can also be planted in fence lines, field borders, rice paddy bunds and irrigation ditches. They are commonly planted as individual trees or in rows, spaced 1-2 m apart along fence lines, field borders and the bunds of rice paddies.Can be planted at high densities (up to 3,000 stems/ha) to produce pole timber, or sparsely planted to produce dry-season forage and fuel wood.
Companion Species
Agati's sparse canopy and erect habit enables grasses to be grown as a companion plant.
Pests & Diseases
A major problem in raising Agati is its susceptibility to severe pest attacks. Major pests are leaf webbers, leaf feeders and stem borers. In India, the stem borer Azygophleps scalaris has caused some damage. Larvae of the insect Bruchophagus mellipes infest and damage seeds. Highly susceptible to the root-knot nematode Melodogyne incognita. Susceptible to grey leaf spot Pseudocercospora sesbaniae. Sesbania mosaic virus is reported in India and is spread from infected growing trees.
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