Fhatuwani Nixwell Mudau

Effects of nitrogen, phosphorus and potassium nutrition on seasonal tannin content of bush tea (Athrixia phyliciodes DC.)

Three trials were conducted over four seasons (summer, autumn, winter and spring) to determine the nutritional requirements of bush tea regarding nitrogen (N), phosphorus (P) and potassium (K) and the influence of these nutrients on tannin content of cultivated bush tea leaves. Treatments consisted of 0, 100, 200, 300, 400 and 500 kg ha−1 N, P or K in a randomized complete block design with four replications. At the end of each season, tannin contents were extracted using 90% acetone. BuOH-HCl_FeIII reagent was used to analyze condensed tannins while hydrolysable tannins were analysed using potassium iodate. Extracts were analysed with a spectrophotometer. Results demonstrated that condensed and hydrolysable tannins increased in a quadratic fashion in response to N nutrition, reaching a maximum at 300 kg ha−1 N. Maximum condensed tannins (4.5%) occurred in autumn and winter and hydrolysable tannins (0.1%) in spring and summer. In the P trial, both hydrolysable and condensed tannins increased, reaching a maximum at 300 kg ha−1 P, regardless of season. The highest concentrations of condensed tannin (5.0%) were obtained during summer, whereas the hydrolysable tannin contents were best during spring (0.018%) and summer (0.020%). In the K trial, both hydrolysable and condensed tannin contents peaked at 200 kg ha−1 K, regardless of season, with maximum condensed tannins (5.0%) occurring in winter, and hydrolysable tannins (0.021%) in summer. Therefore, for improved condensed and hydrolysable tannins, 300 kg ha−1 N or P and 200 kg ha−1 K are recommended, regardless of season.

Bush Tea as a Herbal Beverage and Medicinal Plant in South Africa

The herbal value of bush tea has always been realized in South Africa and it has been demonstrated to be of significant value. However, the commercialization of bush tea has lagged behind that of the other herbal teas, such as rooibos and honeybush tea. Bush tea cultivation will contribute to the economy, and will create employment opportunities in rural areas especially in Limpopo, KwaZulu-Natal and Mpumalanga Provinces where it is naturally distributed. The current bush tea findings suggest that in terms of quality attributes and current usage, bush tea has an enormous potential to be developed as a competitive commercial product. Bush tea is proven to have no toxicity effects. A lot of exploratory research on micro-propagation and fertilization, effects of environmental factors on quality, and on utilization of bush tea as a beverage has taken place. There are also several reports on usage of bush tea by local communities. Further research should focus on field scale production management, quality and economic viability.