Saraca asoca

Plant Profile

Saraca asoca - tree

Therapeutic uses

• Stem bark of Asoka tree is strongly astringent and a uterine sedative, uterine tonic, and styptic, having a stimulating effect on endometrial and ovarian tissue.
• The bark is also useful in dyspepsia, fever, and burning sensation.
• It is also used to treat menorrhagia, leucorrhoea, internal bleeding, hemorrhoids, and hemorrhagic dysentery.

Morphological characteristics

• Sita Asoka is a medium-sized, evergreen tree with beautiful fragrant flowers.
• Leaves are alternate, paripinnate, copper red when young and green when mature, and 30–60 cm long.
• Bark on old stems is dark green in colour, often marked by bluish and ash white patches of lichens.

Floral characteristics

• Fragrant flowers are orange or orange yellow in colour.
• Fruit is a four to eight seeded, flat and black coloured, leathery pod.
• The pod is dehiscent, woody, and tapering at both ends.
• Seeds are ellipsoid–oblong and compressed. Flowering and fruiting occur from July to October.

Distribution

• Asoka is distributed throughout India, naturally frequent in South India, Sri Lanka, Orissa, and Assam.
• The species also occurs in central and eastern Himalayas up to 750 m altitude.
• It is grown as an avenue tree due to its foliage and fragrant flowers.

Saraca asoca - flowering and fruiting

Climate and soil

• Asoka grows well in moist tropical areas with well-distributed rainfall.
• It also thrives well in partially shaded locations.

Propagation material

• Seeds are the most suitable propagation material.
• Mature seeds are collected from more than five to six-year-old plants in December–January.

Agro-technique

Nursery technique

Raising propagules

• The seedlings are raised in a nursery in March.
• The seeds are sown in mother beds or polybags of 25 cm × 20 cm size.
• The potting mixture consists of equal quantities of soil, sand, and FYM (farmyard manure).
• The seeds germinate in about 15 days.

Propagule rate and pretreatment

• Approximately, 2 kg seeds are required for raising seedlings for planting in 1 hectare of land at a spacing of 3 m × 3 m.
• The seeds may be soaked in water for 12 hours before sowing, which improves the germination percentage.

Saraca asoca - seeds

Planting in the field

Land preparation and fertilizer application

• Pits of size 45 cm × 45 cm × 45 cm are prepared at a spacing of 3 m × 3 m.
• The pits are weathered and refilled with topsoil after mixing with 10 kg FYM per pit.
• An additional 10 kg manure should be applied as the follow-up dose during October–November.

Transplanting and optimum spacing

• Two-month-old seedlings are transplanted in the pits during monsoon season in June/July.
• About 1100 seedlings per hectare are required for planting at an optimum spacing of 3 m × 3 m for a pure crop.
• When intercropped with plantation crops like coconut, only about 200–250 seedlings may be planted per hectare, alternating with coconut rows.
• When intercropped with herbs, it may be planted at a spacing of 3 m × 6 m, requiring approximately 550 plants per hectare.

Intercropping system

• Saraca performs better when grown as a mixed crop with perennial trees like coconut, which provide partial shade to the crop.
• Intercropping with herbs and medicinal plants can also be done for earlier economic returns.

Interculture and maintenance practices

• FYM at the rate of 10 kg/tree/year is applied twice: first in May–June while filling the pits and again in October–November at the time of second weeding.
• Chemical fertilizers are not applied.
• First weeding is done one month after planting and the third weeding is done in December.
• The interspaces are kept weed-free either by hand weeding or protected by spraying of non-selective herbicides like 0.8% paraquat or 0.4% glyphosate.
• Partial shade along with frequent irrigation is provided to growing saplings for the first one or two years from December to May.

Irrigation practices

• The crop is raised over high rainfall tracts.
• During the months without rains, the seedlings require frequent irrigation.
• Watering of grown-up trees is done by forming a ring channel around trees’ base to hasten growth.

Disease and pest control

• No serious pest or disease is observed in this crop.

Saraca asoca - intercropping

Harvest management

Crop maturity and harvesting

• Flowering in Asoka takes place in the early growth stage.
• The plant flowers profusely at six to eight years of age and produces fruits during July to October.
• The tree survives for about 50 years.
• It is often felled after it reaches 20 years of age for collecting bark.
• It is cut at a height of 15 cm from the soil level.
• If sufficient irrigation and fertilizers are provided, the stumps will regenerate new coppice shoots, which can be harvested again after 10 years.
• Alternatively, the bark can be collected without cutting down the tree.
• The bark is peeled off in vertical strips with 6 cm interspaces between each strip.
• The peeled off area is renewed with fresh bark in one to two years.
• Then, the bark on the other areas can be peeled off without cutting the tree.
• This non- destructive method should be preferred for harvesting.

Post-harvest management

• The bark is dried in the shade, packed, and stored in containers.

Chemical constituents

• Major constituents in the stem bark of Asoka are tannins (0.57%–7.85%), ash (2.43%–6.69%), and other extracts (5.74%–14.07%).
• A large variation has been observed in the quality of Asoka crude drug collected from important markets in the country.
• Age factor may probably be responsible for such quality variations.

Yield

• One tonne of dry stem bark per hectare is produced from a sole crop.
• When grown as mixed crop with coconut, yield is reduced to 0.6 tonne per hectare.

Source : Agro-techniques of selected medicinal plants