Variation in polyphenolic content of Athrixia phylicoides (L.) (bush tea) leaves with season and nitrogen application

The high concentrations of polyphenols present in leaves of bush tea (Athrixia phylicoides L.), a popular herbal beverage with medicinal properties, were examined in wild and cultivated populations to determine their magnitude of variation with season and application of nitrogenous fertilizers. Concentrations of total polyphenols in leaves of wild plants were lowest in March, April and September and highest in June and July, with nitrogenous fertilizer applications below 300 kg ha− 1 N further elevating polyphenol concentrations in leaves of cultivated plants grown under restricted lighting. These findings, which contradict the Carbon/Nutrient balance hypothesis, conclude that the most suitable conditions for cultivating bush tea to obtain plants with an optimal leaf polyphenol content are those of reduced light intensity during winter and in soils supplemented with a nitrogenous fertilizer.