Introduction
Vetiver or khus(Vetiver zizanioides) is a tall, perennial grass which grows wild in drier, periodically flood inundated tracts, of western and north central India. It produces spongy, much branched, root system(khus root)with fine rootlets, containing a fragrant oil which is a perfumes by itself. The dry aromatic roots are also to make curtain, mats, fans and other fancy goods as the product emits a sweet cooling aroma for long period when moistened. The oil is used as a valuable fixative in blending of perfumes, cosmetics and scenting of soap. Its cultivation is largely scattered over small holdings in Kerala, Karnataka, Tamil Nadu and Andhra Pradesh and to a lesser extent in Uttar Pradesh. Considering the high quality of oil produced in India compared to Indonesia, Brazil and Haiti, the north Indian Type Vetiver oil has good potential for export.
Khuu’s occurs wild in wet and damp environment, common over marshy lands in south-east Rajasthan, Haryana, and north –central Uttar Pradesh up to 1,200m elevation in the Himalayan foothills. It produces long, narrow leaves(75cm X 0.8cm) from a small stout rhizomatous tuft, having glabrous joints and scribed margin. The inflorescence is long, narrow, panicle (15-40cm)bearing numerous racemes ,in whorl, in central axis. Each spike has 2 florets, one is sessile and bisexual while other is stalked and staminate. The plants profusely bloom in north India and set viable seeds. But its commercial plantation is raised by only from rooted slips to maintain genetic purity and quality of the oil. It is unique xerophytes, which survives under seasonal flooding, endures long periods of drought and tolerates a fair degree of soil salinity and high atmospheric temperature .It is good soil binding property and can stabilize eroded slopes and bunds. The roots can travel long distance in light sandy soils to get moisture.
Two genotypes of vetiver are found in India. The first group is called as north Indian type, represented by Bhatpara bird sanctuary material(Rajasthan).It has thick stem, narrow leaves, profusely flowering with medium-growing and highly fragrant roots but has low oil content(0.2-0.8%).The oil is levorotatory. The other one is represented by material grown in Kerala and Karnataka. this genotype grows all over south Asia and Latin America. It has broader leaves, bushy growth, biennial flowering and high pollen sterility. Its roots are more branched, and produces higher iol content(0.6-1.2%).its oil is dextrorotatory in nature. Two commercial varieties have been developed in India. They are Hybrid 8 and Sugandh. These yield 14-18kg of oil with high vetiver content(70-85%).In south India, variety Nilambur is popular in Karnataka genepool. It produces high oil content(20kg oil/ha).the oil is dextrorotatory in nature.
Vetiver prefers sandy loam soils(6-8pH) in warm and damp weather conditions. It grows luxuriantly over higher rainfall tracts of Kerala and western Ghats region. The growth ceases in winter season in north India. A medium fertile soil is ideal. Clayey soils, where root growth is poor, should be avoided for its cultivation.
The land is deeply ploughed by cross harrowing .It is kept open for weathering to hot sun for 10-15 days. thereafter, it is levelled and laid out into beds. The farmyard manure @ 10 tones/ha together with 25kg of BHC(5%),and 20,40 and 20kg each of N,P,K fertilizers are added at land preparation.About15-20 cm long-rooted slips are separated from old root clumps. These’re planted at 60cm X 25cm during July-august, maintaining a plant population of 60000/ha. Their growth is slow in first 90 days. there fore, intercropping with cowpea(fodder),cluster bean ,black gram and green gram is advised. The crop is given additional dose of 60kg of N as topdressing. The plants are earthed up after planting when one-third N is top dressed ; remaining N is given in early spring season. About 2-3 intercultural operations are done to control weeds. A pre-emergent application of Atrazine or Oxadiazine (0.5kg in 800 gallons of water)control weeds in early kharif season(where intercropping is not done).It needs 8-10 irrigations of 5cm onset of autumn season to facilitate tailoring, good root development and reduce incidence of leaf-blight on regrowth.
The roots are dug out at 15-16 months after planting in next autumn. If delayed, its oil content reduces. Digging is expensive operation. Use of one disc in a disc plough, which may turn soil at 30cm depth, is recommended. The dug out roots are separated, cleaned and dried for 7-10 days in shade(till 10% moisture remains in them.) the roots are light in weight and yellowish in colour, taking 24-36 hr. to exhaust all oil content when charges in steam distillation under pressure. Dark coloured heavy viscous oil is received with highly persistent fragrance. Since the oil of high boiling fractions is obtained in the later part of distillation, the distillation is continued for long time so that it is not lost. The oil can be stored in aluminum containers, filled up to the brim and remains stable for a fairly long period but storage of roots over 30 days begins to lose its oil content and large percentage of the oil is lost in 6 month of storage.