Between 2001 and 2002, plant collections from wild populations of Norwegian tansy (Tanacetum vulgare L.) were studied with a focus on essential oil (EO) yield and composition in order to characterize the chemotypical EO variability. Tansy collections of 40 different locations from North, Mid-, and South Norway were transplanted to the Apelsvoll Research Centre Div. Kise in 2000 and grown for 2 years before the aerial parts (leaves and flower buds) were harvested in June 2002. The EO from individual plants was isolated from dried plant material by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS) on a DB5 column at the Plant Biocenter. The EO yield ranged between 0.35 and 1.90% (v/w) (average: 0.81%); the most abundant thujone plants were especially rich in EO volatiles (0.95%). On the basis of GC-MS data, seven chemotypes could be identified as follows: A, alpha-thujone (two individuals); B, beta-thujone (22); C, camphor (six); D, chrysanthenyl acetate/chrysanthenol (three); E, chrysanthenone (two); F, artemisia ketone/artemisia alcohol (three); and G, 1,8-cineole (two). The thujone chemotype was dominated by beta-thujone (81%) associated with alpha-thujone, but tansy plants rich in alpha-thujone were also detected (61%). The chemotypical classification of Norwegian tansy genotypes was underscored by preliminary studies from 2001, indicating the genetic uniformity and biochemical stability of the domesticated plants.

In the period from 2000 to 2002, studies on peppermint (Mentha x piperita) herb and essential oil (EO) production have been conducted at Planteforsk, Apelsvoll Research Centre Div. Kise in Norway. The trials were aimed at finding the optimal harvest date and suitable drying methods to maximize EO yield and to obtain a desirable oil quality. Peppermint plants from the first production year (2000 and 2001) and the second production year (2002) were harvested during flowering at three developmental stages (early, full, and late bloom). Biomass and leaf production were recorded, and the water content of the plant material was detected after the application of different drying methods: instantaneous drying at 30, 50, and 70 degrees C and prewilting (ground drying) for 1 or 5 days followed by final drying at 30 degrees C. Finally, plant samples were transferred to The Plant Biocentre at NTNU, Trondheim, Norway, for hydrodistillation and gas chromatography-mass spectrometry (GC-MS) analyses of the EOs. Peppermint oil yield increased from early to full bloom and late bloom (average of all years and drying methods except for 50 and 70 degrees C: 2.95, 4.13 and 4.20 L/daa, respectively) as an effect of biomass production and leaf growth. The flavor-impact compounds, menthol and menthone, reached their optimum at full bloom (43-54 and 12-30%, respectively). Prewilting led to slight decreased EO levels after 1 day (7.7%) and 5 days of ground drying (1.5%) and no EO quality changes, compared to direct drying at 30 degrees C. The plant weight (H2O content) was drastically decreased to the average under 80 and 45% in all years, thus reducing the energy supply and costs for the necessary final drying step.

Tansy (Tanacetum vulgare L.) was cultivated at the Norwegian Crop Research Institute at the Apelsvoll Research Centre, Division Kise, in the period from 2000 to 2001. The study focused on different harvesting regimens for high biomass production and essential oil (EO) yield and quality. Two tansy genotypes from Canada (Richters and Goldsticks) and three Norwegian genotypes (Steinvikholmen, Alvdal, and Brumunddal) were studied. The Canadian genotypes reached a height of 130-145 cm and showed a higher dry weight of aerial plant parts compared to the Norwegian plants in 2000. Similar oil yields could be observed for the Canadian types and genotype Steinvikholmen in the range of 30.8-34.6 L/ha when the plants were harvested twice during budding and before flowering after regrowth (year 2001). In contrast, single harvesting at the full bloom stage resulted in higher oil yields, between 42.1 and 44.5 L/ha (Canadian genotypes), whereas 21.0-38.4 L/ha was obtained from the Norwegian types. Tansy genotypes could be grouped into the following chemotypes: the mixed chemotypes Steinvikholmen (thujone-camphor), Alvdal (thujone-camphor-borneol), Goldsticks (thujone-camphor-chrysanthenyl type), and Brumunddal (thujone-camphor-1,8-cineole-bornyl acetate/borneol-alpha-terpineol) and the distinct chemotype Richters, with average concentrations of (E)-chrysanthenyl acetate >40% in both leaf and flower EO.