Asam gelugor, asam keping, kayu gelugur, gelugur
‘Asam gelugor’ is a large evergreen perennial rainforest tree native to Peninsular Malaysia and found growing wild through out the country and Southern Thailand. In Malaysia, the plant is widely cultivated in the northern states due to good economic and medicinal value. Sun-dried slices of the fruits, locally known as “asam keping”, are commercially available and are popularly used in Malaysian cooking.
|A fully grown ‘asam gelugor’|
The tree can grow to a height of more than 30 metres and has a long trunk, smooth grey bark and spirally arranged drooping branches. The leaves are dark green in colour measuring about 5 cm width and 20 cm long. The fruits are green in colour when young and turn to bright yellow when matured. The fruits are extremely sour in taste and have been used for centuries by the Malaysian folks in the villages both as a cooking ingredient and weight loss agent.
|The leaves are dark green in colour|
Medicinal Properties and Usage
The rind of ‘asam gelugor’ is sliced thinly before being air dried. The dried rinds are used widely in cooking as flavouring agent where sour taste is required. The young shoots are eaten fresh as ulam or cooked with other vegetables. Traditionally, decoction of ‘asam gelugor’ is said to improve blood circulation, reduce cholesterol, and as a treatment for high blood pressure. Expressed juice of leaves and roots is used to treat earache.
Soil Suitability and Climatic Requirement
This plant is suitable to be planted in moderate climatic condition, sub-tropical and tropical areas that receives about 2,000-3,000 mm rain per year. It can also survive well even in marginal soils such as peat but grows best on loam and mineral soils that have drainage.
The normal operations in the land preparations includes, land clearing, disc ploughing and rotovation. Field drainage should be established in areas that are prone to water logging. Planting holes measuring 45 cm X 45 cm X 45 cm are prepared. Triple Super Phosphate (TSP) at the rate 100 g/planting hole was applied as the basal fertiliser. Ground Magnesium Limestone (GML) at the rate of 100 g per planting hole was also used to increase the soil pH to the required level.
Production of Planting Materials
The seeds are normally used in the production of planting materials. The seeds cannot be kept for long term storage. Thus only the fresh seeds that are obtained from the matured fruits are used. The seeds are sown into the polybags measuring 13 cm X 18 cm. The bud collected from the selected successions is sometimes grafted into these seedlings in the production of good planting materials. The grafted seedlings also has shorter maturity period. The seedlings should not be planted in the field before being kept at least 24 months in the nursery.
The recommend planting distance is about 10 m X 10 m. This will give the population density of about 100 plants/ha. To avoid the planting stress, planting should be done at beginning of the rainy season. Intercropping with other shirt term cash crops is recommend at the early stages of crop growth to maximise land utilisation.
Three types of fertilisers are recommended that is chicken dung, NPK (15:15:15) and NPKMg (12:12:17:2). Chicken dung at the rate of 15kg/plant should be given once a year for the first three years. NPK (15:15:15) on the other hand should be given at the rate 100 g/plant at 3 months intervals. The NPKMg (12:12:17:2) should be given at the rate of 300 g/plant at 4 months intervals from year four onwards.
Manual weeding or rotor tillage operations between rows can helps to eradicate weed during the early crop growth. If there is a need to use chemicals, only the contact herbicides are recommended. Application of organic mulch around the planting points can also help to control weeds.
In order to reduce the effect of planting stress, field planting should be conducted during the wet seasons. Supplementary irrigation by using drip system is applied during the early stages of crop growth.
Pest and Disease Control
Currently, there are no serious pest and disease problems on the field planting of ‘asam gelugor’.
The plants normally start to bear fruits at 5 to 6 years after field plating. The matured fruits are harvested when it starts to turn yellow in colour. It takes about 100 to 120 days from anthesis. The harvesting poles are used. The yield potential depends on the crop maturity. An average yield per hectare for over 20 year period was estimated to be about 9.5 t/year.
|'Asam gelugor’ fruits|
The fruits are firstly cleaned while the seeds and the fruits stalks are then removed. The rind of the fruits are then thinly cut to facilitate the drying process. The slices are then sun-dried for about 2 to 3 days before being marketed as “asam keping”.
|The rind are slice into small pieces (about 1 cm thick)|
|The drying of sliced rind of ‘asam gelugor’|
The estimated cost of production for a 20 year period is RM 52,000/ha. This cost covers the cost of land preparations, planting materials, planting and crop maintenance. For the total fresh yield of about 192,000 kg, the cost of production for a kilogram of fresh fruit is RM 0.30. The production cost was estimated based on the cost of current inputs during writing of this article.