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W. Letchamo and A. Gosselin

Camomile (Chamomilla recutita Rauschert) is an annual plant from the Asteraceae. Camomile is one of the most frequently used medicinal plants, and has a commanding place in the world market. The flower heads are used in pharmaceutical preparations, and the cosmetic and beverage industries. The extracts from camomile flowers, to mention some, are known to have the most-effective sedative (3.29× compared to papaverin), antidepressive, tumor -protective, antiinflammatory, and accelerative properties in the regeneration of skin tissues. It is considered a panecia, due to its strong effects among many others, in the treatment of gastric ulcers, stomatology, respiratory complications, nephritis and nephrolithiasis (dilution of the kidney stones), and urinary bladder stones (cystolithiasis). Recently, successful research programs have been carried out to develop new camomile varieties with higher flower yield and better content of the active substances, suitable for mechanical harvesting under conventional cultivation. Apart from growing consumer demand for organically grown herbal products, the use of some herbicides and insecticides has resulted in the shifts of the content of active substances. The yield stability, content, and composition of the active substances under organic cultivation, particularly in areas with extreme climatic conditions, such as northern North America, should be investigated. We identified and introduced new camomile varieties and studied their suitability for organic field cultivation in Quebec, Canada. We studied over-wintering ability, yield potentials, and the content and composition of essential oil, flavonoids, and coumarins under field conditions. The physiology of the new varieties, particularly the relationship between photosynthesis and yield formation, and the accumulation of the active substances under different cultivation conditions remain to be studied.

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W. Letchamo, C. Mengle, and A. Gosselin

The content of essential oil, thymol, and carvacrol in a thymol-type of clonally selected thyme plants during different developmental stages were investigated under greenhouse and field conditions. Plants in the greenhouse were grown from July to November, under natural light and natural light supplemented by a PPF of 200 μmol·m–2·s–1, provided by HPS lamps, while plants in the field were studied from June to November. Shoot yield and the accumulation of the active principles from greenhouse-grown plants were determined by harvesting the plants at 40-, 60-, and 120-day intervals, while field-grown plants were harvested in August, September, October, and November. Essential oil content, qualitative and quantitative changes in the oil were determined by subjecting the samples to steam distillation and subsequent gas chromatographic analysis. There were important changes in shoot yield, essential oil, thymol, and carvacrol content in the course of plant development. After 120 days of growth under greenhouse conditions, the essential oil content increased by >150%, while thymol content increased by ≈200% compared with the 40-day-old plants. We found some differences in oil content, thymol, and carvacrol accumulation between field- and greenhouse-grown plants. The pattern of crop yield and the accumulation of the major active substances under field and greenhouse conditions are presented and discussed.