Introduction
Lemon Grass(Cymbopogon flexuous) is a stemless, perennial sedge which grows wild in tropical southern states of India. It is now commercially cultivated in many parts of India. The leaves contains an aromatic oil, with a characteristics lemon like odor, containing 75-80% citral. The oil is used in scenting of soaps, cosmetics, and as disinfectants besides it s aroma compound: citral is a starting material for manufacturing of ionone and vitamins A. the crop is commercially grown in about 30.000 ha land in Kerala and Assam mainly as rain fed crops, whereas smaller acreage is grown in Orissa, Andrapradesh and Karnataka. India has been a large and traditional producer and exporter of its oil, citral and its upstream aroma compounds.
Lemon grass reaches up to 2m tall under cultivation. It produces flowers and sets seeds luxuriantly during autumn under short day conditions only. The inflorescences is a long, terminal, branched panicle, bearing paired spikes, sub-tended by leafy bracts. A spikes consists of 5-11 spikeletels in pairs, of which one is sessile and other one is stalked .the sessile spikelet is awned, holds bisexual florets with 4 glumes while stalked ones are awn less with 3 glumes and staminate floret.
It is maintained for 4 years in fields(rained crop for 6-8 years),allowing 3-4 coppicing of leaves in a year. Several varieties have been developed. Of these, Sugandh is an old primary cultivar grown all over in Kerala. its selection OD 440,yields more oil under rainfed condition. Pragati, another clonal selection with dark purple leaf-sheath, is recommended for subtropical climate of the Himalayan Foothills. RRL 16 and tetraploid mutant Praman having erect, profusely tailoring habit are recommended for growing in fertile ,irrigated lands. They produce higher herbage and oil yields. None of these tolerant shady conditions.
Lemon grass is very hardy, drought tolerant crop, adapted to wide variety of soils and climatic conditions .In Kerala, it is grown as a rainfed crop over sub-marginal, sandy, lateritic soils and hilly sopes. It can tolerate alkalinity to some extent. However, well-drained, acidic, loamy, medium to highly fertile soils under warm tropical climate with high, well distributed rainfall (175-200cm) is good condition for rainfed cultivation. The subtropical tracts (40-100cm) need supporting irrigation. It ceases growth during winter in north India.
The crop is commercially propagated through seed, sown in nursery during April-May. About 4-6 kg of fresh seed is sown in 4 (raised) nursery beds of 60cm X 4cm size. These produce enough seedlings to plant a Ha of land. Seeds lose viability after storing for 8 months to one year. two months old seedling are planted in well prepared fields at 40cm X 15cm during rainy season. Higher spacing (50 cm X 30cm or 60cm X 40 cm) is given when the crop is grown in fertile lands. Compost or well-rotten spent grass and wood ash @2 tones/ha is applied. Kerala farmers, however, seldom use inorganic fertilizer. Consequently, their yields are low. OD 19 and OD 440 respond to 40kg of N,P and K applied basally together with 25-25kg /ha of N top dressed in rows after each harvesting give higher returns. Other varieties under irrigated conditions respond to N application up to 120kg/ha. The crop is given 1-2 intercultural in the first year and one such interculture is given after 30days of each harvesting .Earthling-up improves tillering .Pre-emergent application of Oxyfluron(1.0kg) controls rainy season weeds. Irrigation is given frequently(1-2month) in dry season in north India.
It is harvested after 90days in the first year and after 60-65 days thereafter except in dry summer season. The crop is cut a 20cm above the ground and left for withering for 4-6 hr in the field. It is cut into small pieces later and distilled in a steam distillation unit. It has 0.5 -8.0% oil. It yields 18-20 tones/ha of herbage from rainfed crop and 25-30 tones/ha from irrigated one, producing 80-100kg and 150-150kg oil/kg respectively from well-managed fields. Average citral content varies from 80-86%