Botanical Names
Polygonum minus Huds
Common Names
| Malaysia | Kesum. |
| English | Knotweed. |
| Thailand | Phak phai. |
Family
Polygonaceae
Introduction
‘Kesum’ (Polygonum minus) originated from Southeast Asia countries namely Malaysia, Thailand, Vietnam and Indonesia. It grows wild in damp areas near the ditches, river banks and lakes. It survives well on cool, hilly areas like Cameron Highlands and Genting Highlands.[1]
Morphological Features
‘Kesum’ is a herbaceous plant which is described as shrubby, lanky and creepy. It achieves a height of 1.0 m on the lowlands and 1.5 m on the hilly areas. The leaves are long and lanceolate measuring about 5-7 cm long and 05-2.0 cm wide. The dark green leaves are aromatic and arranged alternately on a stem. The stem is cylindrical, green and slightly reddish having short internodes with nodes that are easily rooted. Generally, there are two types of ‘kesum’ available namely creepy and vertical-growing. For commercial production, the vertical type is more suitable for efficient field maintenance and harvesting.[1]
Medicinal Properties and Usage
‘Kesum’ is popularly used as an ingredient in many Malaysian dishes. Traditionally, decoction of ‘kesum’ leaves is used to help in digestion, getting rid of scalp and as tonic taken after birth. Nutritionally, ‘kesum’ is rich in beta-carotene, vitamin A and vitamin C as well as minerals such as potassium, calcium and phosphorus. As a natural source of aliphatic aldehyde, ‘kesum’ oil is believed to have high potential in flavour and fragrant industries due to the scarcity of aliphatic aldehyde in the market.[1][2][3]
Soil Suitability and Climatic Requirement
In general, ‘kesum’ can be planted on various soil types from mineral to peat soil provided sufficient water supply is available. It requires well-distributed rain during planting and growing with a total of 2,500-3,000 mm annually. The areas with dry period of more than one month are not suitable for growing of ‘kesum’ unless irrigation is made available.[1]
Field Preparation
Land Preparation
Prior to planting, the land has to be prepared thoroughly. One round of disc plough followed by two rounds of rotovation is normally done to obtain good and friable soil suitable for ‘kesum’ planting.[1]
Production of Planting Materials
‘Kesum’ is easily propagated through stem cuttings. The stems of 15-20 cm long having 5-7 nodes are used. The cuttings are soaked for 7-14 days in water to induce rooting before field planting.[1]
Field Planting
The recommended planting density is 70,000 plants/ha. It is planted at 55 cm between rows and 25 cm between plants in a row in two hedge rows. These planting distances are to accommodate the use of machines for crop cultivation and harvesting. Planting is normally done at the onset of the rainy season.[1]
Field Maintenance
Fertilisation
Fertiliser at the rate of 80–100 kg N/ha, 50 kg P2O5/ha and 70 kg K2O/ha is recommended for good growth and optimum leaf yield. Fertiliser is split into three equal parts and applied at the 4th, 8th and 12th weeks after planting. For ratoon crop, the fertiliser is applied during the 1st, 5th and 9th week after harvesting of the main crop.[1][4][5][6]
Weed Control
Pre-emergence weedicide is sprayed after land preparation to inhibit weed seeds in the soil from germinating. The pre-emergence weedicide is able to control weeds effectively for 1–1½ months. The second round of spraying is done before the plant canopy has totally covered the area that is at the age of 2–2½ months after planting. Weeds that grow at later stages can be removed manually.[1]
Water Management
Sufficient water supply is very crucial for the good growth and high yield of ‘kesum’. Irrigation is critical during the first month after the rooted cuttings are transferred to the field. Without rain, the plants have to be watered daily. Watering is required for the first two months after field planting. Irrigation using sprinkler system is recommended.[1]
Pest and Disease Control
‘Kesum’ is sometimes attacked by thrips and aphids. Practising good sanitary practices can solve the problem.[1]
Harvesting
The main crop is harvested at 16−18 weeks after field planting. Harvesting is done by cutting 10−15 cm above the ground level using a shear. Sickle bar mower and reaper-binder can be used when the planting area is bigger than 0.5 ha. Ratoon crop is harvested at every 14–16 weeks after the first harvest depending on the growth condition of the plants. The yield starts to decline at the third and subsequent harvests. Therefore, ‘kesum’ is recommended for replanting after the third harvest (one round of main crop and two rounds of ratoon crops). Potential yield of fresh ‘kesum’ is 80−100 t/ha annually. The yield is based on three harvests that is one main crop and two ratoon crops.[1][4][5][6]
Postharvest Handling
‘Kesum’ is dried under the shade for one day to reduce the moisture content by 40% before the distillation process. The distillation process takes about two hours. The amount of extracted oil obtained is about 0.05%. The potential yield of extracted oil of ‘kesum’ is 40–50 kg/ha for each round of planting consisting of three harvests.[1][4][5][6][7]
Estimated Cost Of Production
The estimated cost of production of fresh ‘kesum’ is RM0.10/kg. The cost is based on the fresh ‘kesum’ yield of 80 t/ha and the production cost of RM11,000/ha including the cost of irrigation system and harvesting machine. The cost to produce a kilogramme of extracted oil is estimated to be about RM580 based on the extracted oil yield of 40 kg/ha and the total cost of RM23,300. The production cost was estimated based on the cost of current inputs during writing of this article.[1]
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References
- Abd. Rahman Azmil, I., Ahmad, A.W. and Omar, T. 2005. Kesum (Polygonum minus Huds). In: Penanaman tumbuhan ubatan & beraroma. (Musa, Y., Muhammad Ghawas, M. and Mansor, P., ed.), Pg. 102-107, Serdang : MARDI
- Anon. 2002. Compendium of Medicinal Plants Used in Malaysia (Vol. 2) Pg. 212, Kuala Lumpur : HMRC-IMR
- Karim, Y. 1987. Kesum oil – A natural source of aliphatic aldehyde. Perfumer and flavouris. 12: 27-30.
- Abd. Rahman Azmil, I., Omar, T. and Ahmad, A.W. 2001. Effect of agronomic practices on the yield and oil quality of kesum (Polygonum minus). J. Trop. Agric. and Food. Sc. 29(1):1-6.
- Abd. Rahman Azmil,I., Ahmad, A.W., Omar, T. and Hamdan, M. 2000. Cultivation of kesum and extraction of its essential oil. Technical paper presented at MARDI Scientific Council, 30 Mac 2000, MARDI Serdang, Selangor.
- Ahmad, A.W., Abd. Rahman Azmil, I. and Liew, K.L. 1998. Kesum (Polygonum minus)– Potential commercial crop. Conference on Herbs–The Way Forward for the Next Millannium, 19th September 1998. The Mines Resort Hotel, Serdang, Selangor.
- Ahmad, A.W., Abd. Rahman Azmil, I., Mohd Noh, J. and Liew, K.L. 1999. Production and processing of essential oils (tea-tree, kesum, patchouli and vanilla). International Conference and Exhibition on Herbs, 9-10 November 1999. The Mines Resort Hotel, Serdang, Selangor.
