General plantation of citronella cv. Java 2 was maintained following recommended agricultural practices at the Experimental Farm of Central Institute of Medicinal and Aromatic Plants, Field Station, Hyderabad, India. The experimental station has a semi-arid tropical climate. The experiment was conducted in the same plantation for 2 consecutive years during the summer month of June 1996 and 1997, when the incidence of the disease was higher. In each year, 12 each of healthy and diseased plants were selected at random and harvested. The occurrence of the disease is generally observed during the hot summer season months, when the temperatures are in the range 36-43 ℃. Initial symptoms of the pest attack appear as yellow specks or blotches, mostly along leaf margins, that in later stages develop into yellow streaks running along the length of the affected leaves. Emerging young leaves are pale green to yellow coloured, twisted, crinkled, developed into whip-like structures and in severe cases of infection fail to open. Even if they do open, these leaves fail to exhibit a smooth leaf surface. Severely affected older leaves turn brown, dry and die. The overall growth and development of the infected plant is severely affected, giving it a dwarfed and unhealthy appearance.

The essential oil examined by GC and GC-MS from cultivated healthy plants contained citronellal (28.4%), geraniol (24.8%), citronellol (11.8%) and elemol (10.2%). The major components from diseased plants were geraniol (19.0-25.5%), elemol (15.3-20.4%), citronellal (13.4-19.1%) and citronellol (12.9-15.1%). Caryophyllene oxide (3.5-6.0%) was an important minor component.

Plant material: Samples of L. latifolia were collected in August 1998 during the full flowering period (L/La) and in October 1998 during the fruiting period (L/Lb) from three different spike lavender populations located into the Cazorla, Segura y Las Villas Natural Park (Jaen province, Spain). The plant material from each population consisted of the twigs of several single plants. L/La (Location: 'Garganta de Hornos', Altitude (m): 950, Harvesting date: August 14, 1998, Phenological stage: Flowering); L/Lb (Location: 'Garganta de Hornos', Altitude (m): 950, Harvesting date: October 15, 1998, Phenological stage: Fruiting).

The small amounts of linalool needed to match the standard can be reached in a natural way (from full flowering to fruiting) which means it is important to choose the most convenient time of harvest in the studied area.

The aerial parts of M. camphoratum were collected at Manaus, Amazonas (type A) and Vigia, Para, (type B).

The plants were collected from two different localities in the Amazon Region and their oils were found to be remarkably different. One oil obtained from the sample collected at Manaus was characterized by a high content of terpinolene (30.3%), limonene (13.8%) and delta-3-carene (13.2%). The main constituents found in the other oil distilled from a sample collected at Vigia were camphor (15.0%), alpha-phellandrene (20.5%) and beta-caryophyllene (8.9%)

Aerial parts of Ocimum basilicum var. purpurascens Benth, Ocimum basilicum var. dianatnejadii Salimi at flowering stage were collected from plants grown in Experimental Station of Pykan Shahr, near Tehran. Elevation 1215 m above sea level, latitude 35° 42′ North, 51° 8′ East, average humidity 36% and climatic category semi-arid.

Methyl chavicol (43.0%) and linalool (28.9%) were identified as the major compounds in the oil of O. basilicum var. purpurascens, while methyl chavicol (37.6%), linalool (33.4%) and alpha-cadinol (5.7%) were the major constituents in the oil of O. basilicum var. dianatnejadii.

Seeds of Ocimum basilicum cv. keskenylevelu provided from Hungary, were used in this study. Potted seedlings of Ocimum basilicum were subjected to study the effect of different irrigation rigimes on the essential oil content and composition at experimental farm of college of agriculture, Tarbiat Modarres, University, located in Tehran. (1215 m above sea level, latitude 35° 43′ north, altitude 51° 8′ east). The seeds were sown in spring of 2001 in pots. The irrigation regimes to induce of water stress were: 100%, 85%, 70% and 55% of field capacity. This percentage of field capacity kept constant in the soil by daily weighting of pots. The soil was sandy-loam with 22.6% of field capacity. The harvest of whole plants was performed at the beginning of the flowering stage.

The essential oil content of herb increased from 1.12 to 1.26% as plant water deficit increased (till 70% of field capacity). The number of component of the oil of Ocimum basilicum increased as water stress increase. Amount of the main constituents of the oil such as linalool, methyl chavicol, 1,8-cineole and trans alpha-bergamotene significantly affected by water stress.

The 36 'Genovese' and 24 'Foglia di Lattuga' samples preliminarily analysed were grown in Tavazzano (MI), and harvested at flowering, from 5th to 10th August 1998. The breeding program started in 1999, by crossing several selected lines of 'Genovese' with 'Foglia di Lattuga' and 'Compatto'. Selected F1 plants were selfpollinated in 2000. Plants of the F2 (2001), F3 (2002) and F4 (2003) generations were selected on the basis of agronomic and morphologic traits, and self-pollinated. Only the seeds from self pollinated plants with satisfactory essential oil content and composition were used to obtain the next generation. In 2004, some F4 plants were replanted in order to evaluate their stability in relation to environmental variations. All leaf harvests were carried out at flowering.

Genovese' showed higher essential oil and linalool content, with almost total absence of methyl chavicol, very abundant in 'Foglia di Lattuga'.

Plant material and horticultural practice: The experiments were conducted at the Universidade Federal de Lavras between November 2005 and January 2006. Seeds of O. selloi were sown in commercial substrate [Plantmax (Eucatex, Sao Paulo, SP, Brazil)] contained in 72-cell plastic trays and maintained in the greenhouse under intermittent nebulization for 60 days. Seedlings were transplanted to 10 L pots containing a substrate consisting of soil, matured cattle manure and sand (5:3:2), and cultivated under three different light regimes, namely, full sunlight, and sunlight with blue or red shading. Each treatment was repeated seven times and two plants were employed per repetition.

The compositions of the oils varied according to the quality of light. Although the qualitative profiles of the oils of plants grown under full sunlight or red shading were similar, that obtained from plants grown under blue shading presented a larger number of constituents. The highest level of methyl chavicol (93.2%), the major component of the oil, was observed in plants grown under full sunlight.

Plant materials were collected from Chalous Road (north of Tehran province) both at the flowering stage in June and the seed stage in September 2003. The fresh plants were dried at room temperature. Dried stems/leaves (S/L) (collected during flowering stage), seeds (S) were hydrodistilled for 3 h in a Clevenger-type apparatus to produce the oils.

The major constituent in the stem/leaf oil was trans-alpha-bergamotene (77.1%), whereas the major constituent of the seed oil was pregeijerene (87.0%). Nonadecane (8.6%) were the other major constituents in the stem/leaf.

The branches of pine were collected in July, 1996 in 15 different locations in Lithuania in the following regions: Western part (Silute, Jurbarkas, Kursiu Nerija), Eastern part (Salcininkai, Zarasai, Moletai), Southern part (Varena, Trakai, Radviliskis) and central part (Ukmerge, Jonava, Kaisiadorys). The branches in each location were collected from the trees in approximately 1 km radius.

More than 70 constituents were identified (64 positively and 10 tentatively) in the oils. alpha-Pinene (18.5-33.0%) and delta-3-carene (9.1-24.6%) were dominating constituents with the only one exception when the germacrene-4-ol content in one of the samples was 13.2%. The important bornyl acetate content varied from 0.5% to 3.0%. The main sesquiterpenes were beta-caryophyllene, germacrene D, bicyclogermacrene, delta-cadinene, gamma-cadinene, germacrene D-4-ol, cubenol (2.0-5.1%) and alpha-cadinol (1.9-7.7%).

The cultivars selected for this study are Sreekara, Vellanamban and one Indonesian cultivar Kutching grown in Kerala. These cultivars are commonly cultivated in the northern parts of Kerala. The fresh berries of the authenticated cultivars were collected from Indian Institute of Spices Research, Calicut and were dried in a cross flow drier at 45 ℃ and taken for the analysis.

The main components of vellanamban oil were sabinene (3.9-18.8%), beta-pinene (3.9-10.9%), limonene (8.3-19.8%) and beta-caryophyllene (28.4- 32.9%). Sreekara oil contained as major compounds beta-pinene (0-11.2%), limonene (20.1-22.1%) and beta-caryophyllene (16.8-23.1 %). Kutching oil contained alpha-pinene(2.3-5.4%), sabinene (6.7-13.3%), limonene (14.5-17.5%) and beta-caryophyllene (20.8-39.1%).

Wild growing Tanacetum dolichophyllum samples were collected during the period of full flowering, between September-October 2009 from high alpine meadows of Western Himalaya (Uttarakhand, India): Sample I (Dayara, altitude 3200 m) and Sample II (Tungnath, altitude 3800 m).

Plant collected from Dayara meadow (Sample I) afforded cis-lanceol (11.8%), beta-pinene (10.7%), (E)- beta-farnesene (7.4%), alpha-bisabolol (7.2%), beta-eudesmol (5.2%) and terpinen-4-ol (5.1%) as the major constituents, whereas in the sample collected from Tungnath (Sample II) beta-eudesmol (31.4%), alpha-bisabolol (10.7%) were the most abundant components followed by neryl acetate (5.8%) and (E)-beta-farnesene (5.7%). The composition was dominated by sesquiterpene hydrocarbons and oxygen containing sesquiterpenes (49.2-71.1%). The oils are clearly different from those of all other previously reported T. dolichophyllum oils.

Aerial parts of T. larvatum were collected in July and August during a five-year period, starting in 2001, in Montenegro on several locations: Planinica (Sample a), Visitor (Sample b) and Sinjajevina (Sample c).

Sixty-four components were identified, representing 83.1%, 96.6% and 89.4% of the total oils content in the Planinica [Sample a], Visitor [Sample b] and Sinjajevina [Sample c], respectively. The major constituent in Samples a and b , was oxygenated monoterpene, trans-sabinyl acetate (38.1% and 55.8% respectively). Monoterpene hydrocarbons, beta-pinene (13.5%) and santolinatriene (30.6%), were found to be the dominant components in Sample c. The toxic trans-sabinyl acetate was present only in traces in this sample. trans-Chrysanthenyl acetate, as one of major components in feverfew essential oil, has not been previously identified in the investigated essential oils.

The aerial parts of T. chamaedrys were collected at the flowering stage in June 2004 near Corti, Corsica, France and near Oristano, Sardinia, Italy

The Corsican and Sardinian oils of T. chamaedrys investigated in this study were qualitatively similar but they differed by the amount of their major components. The major components were beta-caryophyllene (29.0% and 27.4%, respectively) and germacrene D (19.4% and 13.5%, respectively), followed by alpha-humulene (6.8%) and delta-cadinene (5.4%) in the Corsican oil and by caryophyllene oxide (12.3%) and alpha-humulene (6.5%) in the Sardinian oil. These quantitative differences are also noticeable on the amounts of the different class compounds. Especially, the monoterpene hydrocarbons amounted for 10.3% and 4.1% in Sardinian and Corsican oils respectively and the oxygenated sesquiterpenes amounted for 18.9% and only 7.4% in both oils, respectively. Both oils were qualitatively rather similar in comparison with those reported in the literature from various geographic regions. However, among the 87 components identified in this study, 47 minor components (< 0.6%) reported were identified for the first time in T. chamaedrys oil. This study confirms the quantitative variability of the major components according to the plant origin.

The aerial parts of T. flavum were collected in different periods from December to July 2006, from plants growing along the Ionic coast of Sicily (Italy). LF 1-LF 2-LF 3: represent the composition of leaf oils of plant samples collected in December (vegetative stage), February (pre-flowering stage) and April (budding stage) respectively; FL: flower oil; FR: fruit oil.

Some components, in all investigated plant parts, remained more or less constant during all the different phases of the plant cycle life. Worthy of note, considering the leaf oils, was that beta-pinene, limonene and germacrene D increased in the pre-flowering stage, while a series of esters and alpha-copaene, beta-caryophyllene, viridiflorol, Tmuurolol and phytol increased in the budding stage (LF3); the vegetative stage oil is generally characterized by a rich chemical composition and some constituents such as isoamyl hexanoate, alpha-humulene, bicyclogermacrene, beta-bisabolene and alpha-bisabolol reached their highest levels in this oil. In the flower oil, linalool and 1-octen-3-yl acetate were the main components compared to the amounts found in the other oils. Fruit oil composition was relatively oil poor, with beta-bisabolene, caryophyllene oxide, cadin-4-en-1-ol and phytone as the major constituents.