LOCALIZATION AND CONTENT OF THE CHAMOMILE ESSENTIAL OIL

The essential oil is synthesized and accumulated predominantly from the flowers�

The glandular trichomes present on tubular florets of the capitula have been shown to contain essential oil� When the florets are exposed to chlorine or bromine (10% chlo-roform solution), appearance of blue color in the trichomes confirms the presence of chamazulene, which is a characteristic constituent of the essential oil of chamomile (Vaverkova and Herichova 1980)� The essential oil is also present in the herb (leaves and stem) and the root� Anatomical investigations had revealed that the oil is pres-ent in the modified parenchyma: oil cells, idioblasts, and schizogenous oil passages (Jackson and Snowdon 1968)� Glandular hairs have been found in the stems, which secrete essential oil� In addition, schizogenous ducts are also found in the stem and roots, which secrete essential oil (Andreucci et al� 2008)�

The essential oil has also been found in callus cultures� The oil has been distilled from callus (Magiatis et al� 2001) and from genetically transformed hairy roots (Szöke et al�

2004a; Szöke et al� 2004c) and the oil content and chemical composition determined�

4.2.1 essential oil Contentin flowers

The essential oil content of the flowers has been reported to be 0�46%–0�67% by Debska in 1958 (Lawrence 1987)� Piccaglia et al� (1993) reported the oil content of seven chamomile varieties grown in Ozzano (Bologna)� These varieties were sourced from Egypt, Argentina, Hungary, Germany, Holland, Czechoslovakia, and Yugoslavia� The oil content in these varieties was reported as follows:

• Egypt—0�22%

• Argentina—0�36%

• Hungary—0�31%

• Germany—0�22%

• Holland—0�22%

• Czechoslovakia—0�29%

• Yugoslavia—0�39%

In 1994, Salamon carried out a breeding experiment on the diploid Bona and tet-raploid Goral varieties of chamomile� He reported that the essential oil content of Bona was 0�93% and of Goral was 1�3% (Salamon 1994)� The ploidy levels determine the oil content in the plant, with the tetraploids yielding more than the diploids� Das (1999) also found that the essential oil content varied widely among different geno-types in India� In the 1995–1996 field experiment, she found that the oil content of 45 chamomile selections grown in Lucknow, India, ranged from 0�15% to 0�2%� In the next year, after selecting 26 genotypes and estimating the oil content in them, she found the oil content to range from 0�42% to 0�76%� The effect of the increase in oil content in the selections in the second year should be attributed to selection for high-yielding genotypes� The genetic aspects of the essential oil content will be discussed in detail in Chapter 5�

4.2.1.1 Variation in Essential Oil Content in Different Locations

The oil content varies with place or location� If the same variety is grown under different climatic conditions, the yield or content of the essential oil gets affected� Many researchers, such as Bazek and Starey, Juracec, Tyihak et al�, von Schanz and Salonen, and Peneva, have reported that the essential oil content in the flowers varies depending on the place of origin and cultivars or variet-ies (Lawrence 1987)� Franz et al� (1978a) reported a difference in the essential oil contents obtained from 14 chamomile varieties cultivated in two different regions of Germany� Gašić et al� (1983) reported that in the flowers of the chamo-mile plants taken from different localities of Yugoslavia, the essential oil con-tent ranged from 0�12% to 0�64%� Franz et al� (1986) reported that the yield of essential oil was found to be extremely variable in the samples collected from different places, such as India, eastern Europe, Egypt, and Argentina, which points out to the effect of ecological factors on the oil content� Salamon et al�

(2010) reported that the naturally occurring chamomile variety collected from 20 localities in Iran had a significant variation in the essential oil content, which ranged from 0�1% to 0�95%� The essential oil content was reported to be 0�3%–

0�4% in south India (Nidagundi and Hegde 2007) and 0�4%–0�5% in northeast India (Tandonet al� 2013)�

4.2.1.2 Variation in Essential Oil Content in Different Stages of Flowering The oil content and oil quality of the capitulum vary according to the stage of capitu-lum development (Motl et al� 1977; 1982; Marczal and Petri 1979; Gasic et al� 1986)�

Franz (1980) studied the essential oil content and composition in the flowers of four chamomile cultivars during their ontogenetical development� They divided the flower development into four stages: I, buds; II, ligulate flowers developed; III, tubu-lar flowers opened; and IV, decaying flower heads� On commencement of flowering, the flowers were harvested five times in intervals of a week� On steam distilling the oil, they found that the flowers of stages I (0�85% oil) and III (0�9% oil), that is, the buds and the tubular flowers opened, had more essential oil content than stages II (0�75% oil) and IV (0�6% oil)�

4.2.1.3 Variation in Essential Oil Content Due to Farming Practices

A variation in the essential oil content is attributed to farming practices such as growing season, plant spacing, irrigation schedule, fertilizers, and harvesting time�

Franz et al� (1985) studied in detail the effect of sowing time on the essential oil content using two varieties of chamomile H-29 and BK-2� The seeds of these two varieties were sown in August, September, October, April, May, and June in the years 1979–1980 and 1981–1982� They found that there was a variation in the essen-tial oil content in the flowers� The essenessen-tial oil content of the H-29 variety was found to range from 0�7% plants grown in April (1980) to 1�04% in those grown in June (1980)� The essential oil content of the BK-2 variety was found to range from 0�60%

in plants grown in April (1980) to 1�00% in those grown in October (1979)� They reported that sowing in spring led to less yield than that in autumn� Highest oil contents were obtained when the sowing was done in late spring� This variation

clearly shows that the sowing time has an impact on the essential oil content and has to be taken into consideration during cultivation to make optimum use of the climatic conditions�

Franz (1980) had reported, as mentioned earlier, that the flowering stages at the time of harvest determine the essential oil content� They further reported that the harvesting dates may be optimized according to the flowering stage� The flowers may be harvested during stage III, and the most favorable time would be 1 week after the beginning of the flowering (Franz et al� 1985)�

The irrigation and fertilization regime also seems to have an indirect effect on the essential oil content through an increase in the biomass (Franz 1983)� Mirshekari (2011) studied the effect of irrigation and nitrogen fertilizer on the Bodegold variety of chamomile� The irrigation was designed to be given after  60,  120, and 180 mm evaporation� Urea was applied at the rate of 50, 100, and 150 kg/ha� It was applied during planting, stem elongation, and early flowering stage� Irrigating after 180 and 60 mm evaporation resulted in the emergence of buds after 70 and 78 days, respectively� This finding indicates the possibility that less water is required for bud development� Further, it was found that application of urea during planting and stem elongation increased flower yield and consequently the essential oil yield (2�82 L/ha)�

4.2.1.4 Variation in Composition of Organ-Specific Essential Oil

Oil composition also differs depending on the plant parts used� The essential oils of shoot, root, and flowers, show an organ-specific differential distribution of certain chemical constituents� Lawrence (1987) compiled the data from different studies and presented the essential oil content in different parts of chamomile plant, such as the flower, tubular florets, ligulate florets, receptacle, seeds, the plant without flowers, leaves, and stem� The essential oil content in these parts was reported as follows: whole flower (0�91%), tubular florets (0�8%), ligulate florets (0�3%), recep-tacle (0�9%), seeds (0�3%), whole plant without flowers (0�6%), and leaves (0�2%)�

No oil content was reported from the stems or roots� Pöthke and Bulin (1969) reported that a high amount of oil is present in the receptacle and the tubular flo-rets� Reichling et al� (1979) carried out a comparative assessment of the essential oil content and composition of the various tissues such as the stem tumors, roots, and herb� They reported that the stem tumors and the herb (stem and leaves) con-tained essential oil� The oil content in the stem tumor and the herb was found to be similar� Reichling and Beiderbeck (1991) reported that there was 0�6% essential oil in the whole plant without flowers and 0�03% in the roots� Das (1999) studied the oil content and composition of different parts of the plant, that is, the whole flower, tubular (disc) floret, ligulate (ray) floret, leaves, stem, herb (leaves and stem), and root� The fresh parts were used to extract the oil� The oil content was highest in the tubular florets� On the basis of the oil content, the various parts could be arranged in the following order:

Tubular (disc) floret > whole flower > ligulate (ray) floret > leaves > root > herb

> stem�

The average values of oil content and color from the different parts of the chamo-mile plant are given in Table 4�1�

4.3 DISCOVERY OF THE COMPOUNDS IN THE ESSENTIAL OIL