Influence of air temperature on productivity and quality of some medicinal plants under controlled environment conditions

Cultivation of medicinal plants under controlled environment is a good opportunity to study the influence of main exogenic factors on herbal yield and quality. Such studies can give new data about the yield raise of species, as well as about improvement of content and composition of bioactive substances with practical applications. The main purpose of this study was to investigate the effect of different air temperatures (15, 20, 25 degrees C) under controlled environment conditions on herbal yield and content, composition and antioxidative capacity of secondary metabolites of lemon catmint (Nepeta cataria L. f. citriodora), lemon balm (Melissa officinalis L.) and sage (Salvia officinalis L.). It was found, that tested air temperatures had substantial influence on productivity of studied medicinal plants under controlled environment conditions. In case of lemon catmint 20 degrees C gave maximum raw medicinal material, for lemon balm 25 degrees C was more effective, while in sage, both 20 and 25 degrees C were optimal compared to the lowest temperature treatment (15 degrees C). In lemon catmint and sage, 15 and 25 degrees C temperatures provided high content of essential oil, while 20 and 25 degrees C treatments gave maximum recovery of essential oil. In case of lemon balm, 25 degrees C temperature gave high content and yield of essential oil. The composition of herbs' essential oil essentially depended on air temperature, as well as on harvest rounds. Air temperatures had less effect on content of flavonoids. However some differences were noted in connection with harvest rounds. Antioxidative capacity of flavonoid-rich extracts by ABTS-system showed differences according to air temperatures and first or second cut.