Lemon Grass

Cymbopogon citratus/Cymbopogon flexuosus
Family : Graminae

History

The oldest known text about lemongrass oil had been found from the Philippines in the 17th century. It had been introduced to Jamaica in 1799 and to Haiti and USA in 1917. First commercial cultivation of lemongrass was reported in Florida, USA, and Haiti in 1947. It is not known when or by whom introduced lemongrass to Sri Lanka. According to the reports available at the national herbarium in 1905, a Sri Lankan researcher called Mr. J.F Jovit had acquired several plants of “Kochin Sera” (Cymbopogon citrates) From South India and had planted them at Bandarawela Farm for research purposes. Several large-scale cultivations of lemongrass had been existed in Sri Lanka in several decades ago but currently, only a few small cultivations exist.

Products and Uses

Lemongrass is used for oil extraction. It is ranked among the top ten oil-bearing crops in the world and India leads in the world export market  Lemongrass oil is mainly used in the perfumery industry and in the pharmaceutical industry. It is also used in the production of detergents, disinfection and deodorizing compounds. In some countries, lemongrass oil is reported to have been used as a flavoring agent in ice creams, cakes, beverages, confectionaries, puddings and chewing gums. In India, dried lemongrass, mixed with other ingredients, is used in making writing and printing papers.

Major Growing Areas

In Sri Lanka, lemongrass is reported to have been grown in Badulla and Hambanthota area but no exact figure on the extent could be found. Based on the available information it is estimated that the total extent of lemongrass in Sri Lanka is less than 25ha.

Varieties

West Indian Lemon Grass (Cymbopogon citratus) and East Indian Lemon Grass or Cochin Lemon Grass (Cymbopogon flexuosus) are commonly grown varieties.   

Cymbopogon citrates

Commonly called as “Sera” and largely used as a curry leaf in meat preparations. Plant exists as a small bush with long narrow leaves. “Sera” is also used in the oil distillation but the yield, as well as the quality of the oil, is comparatively lower than the lemongrass. The pseudostem is white in color and base of the plant has been formed to a bulb-like structure.  

Cymbopogon flexuosus

It is the commercial lemongrass used in oil distillation. The plant is indigenous to India. Two species of C. flexuosus are reported based on the color of the plant. The pseudostem of C. flexuosus Choomana pullu is red in color.  A bulk of the lemongrass oil is obtained from the red color type of Indian lemongrass. The other type is C. flexuosus forma albescens which have a greenish white or light red pseudostem. The quality of the white lemongrass oil is inferior to the red type variety.

Soils and Climatic needs

Soil:
Well-drained sandy soil is most suitable and hard clay soils are not good for the growth. Most of the poor soil types in Sri Lanka are suitable for lemongrass but higher yield can be obtained from soils with high humus. However, lemongrass can be grown even in the pathana lands, marginal tea lands, severely eroded lands and lands which are not suitable to grow any other crop.
Climate:
It can be successfully grown in almost all climatic zones in Sri Lanka but tropical hot areas with high sunshine are most suitable
Altitude – up to 100-1200 MSL
Temperature – 25ºC – 30ºC
Rainfall – Resistant to severe droughts and severe winds and wildfires. Well spread rainfall with a few inches is adequate. High rainfall reduces the oil yield.
Quantity and quality of oil is low when the lemongrass is grown under high shade, in cooler climates, and in highly fertile soils.

Crop establishment
Planting material:  Both seeds and suckers are used as planting material.
Flower of the Lemongrass is a panicle which produces large number of seeds. After maturity, flowers can be harvested and seeds can be separated after 2-3 days of drying. Seeds can be sown directly to the field and about 25kg/ha of seeds are required for direct seeding. Or else seeds can be sown in nursery beds to obtain plantlets, which can be transplanted in the field. Only 3-4kg/ha of seeds are adequate for sowing in nurseries.
Seeds have to be used as soon as possible since the viability of seeds decline drastically after the harvesting
The common practice of propagation is using suckers. Suckers are separated from mother bushes and planted in the field. About 24000-30000 suckers are required to plant one hectare at the spacing of 60cmx60cm or 60cmx45cm.

Crop management

Fertilizer application
Usually farmers do not apply artificial fertilizer. If applied, higher yield can be obtained.  

Fertilizer recommendation
Recommended mixture – 750 kg / ha.

Components of the mixture
Parts by weight
Nutrient in the mixture
Urea (46%N)1.517%N
Rock phosphate ( 28 % P2O5)1.511% P2O5
Muriate of potash (60% K2O)114% K2O
Age of plantation Maha Season (mixture Kg/ha.) Yala Season (mixture Kg./Ha.)
1st Year (kg)190190
2nd Year (kg)375375

Weed control
2-3 times weeding is necessary in the first year. But in the subsequent years weeding frequency is depending on the condition of the field.   

Soil Conservation
Lemongrass is highly suitable for sloppy lands with high erosion. However suitable soil conservation methods should be applied before planting in high sloppy lands.

Crop protection
No significant pest or disease problems have been recorded in Sri Lanka.

Harvesting and Post Harvest practices

Harvesting
The first harvest can be obtained after 3-6 months after planting. Subsequently, harvest can be obtained after every three months. Yield is low in the first year and the higher yield can be obtained in 3-4 years. Harvesting should be done only in sunny days and grass is cut 10cm above the ground. The harvested grass is spread in the field and allowed to wilt for about two days and make bundles before sending for the processing.
Yield – 3-10 mt. fresh yield/ha

Processing
Water distillation method is used to obtain oil.

Slandered Quality Specifications
Quality of lemongrass oil is guided from the citral content and from the solubility in alcohol.

Lemongrass oil (Cymbopogon flexuosus)
Citral content – should be higher than 75%
Soluble in 70% ethyl alcohol

Sera oil (Cymbopogon citrates)
Citral content is low
Not soluble in 70% alcohol

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