HORTSCIENCE VOL. 40(6) OCTOBER 2005 1898 Plant Growth and Development of Bush Tea as Affected by Nitrogen, Phosphorus, and Potassium Nutrition Nixwell F. Mudau Department of Plant Production, University of Limpopo, Private Bag X 1106, Sovenga, 0726, Republic of South Africa Puffy Soundy and Elsa S. du Toit Department of Plant Production and Soil Science, University of Pretoria, Pretoria, 0002, Republic of South Africa Additional index words. Athrixia phylicoides Abstract. Bush tea (Athrixia phylicoides) belongs to the Asteraceae family. It is a popular beverage used as an herbal tea and as medicine for cleansing or purifying the blood, treat- ing boils, headaches, infested wounds, and cuts, and the solutions may also be used as a foam bath. In some parts of South Africa, people drink bush tea for aphrodisiac reasons. Bush tea was grown under varying N, P, and K levels in all four seasons to determine the seasonal nutrient requirements for improved plant growth. Three parallel trials for N, P, or K one at each season were laid out in a randomized complete block design (RCBD) with six treatments replicated eight times. Treatments consisted of 0, 100, 200, 300, 400, or 500 kg·ha –1 N, P, or K. Parameters recorded were plant height, number of branches and leaves, fresh and dry stem mass, fresh and dry root mass, stem girth, fresh and dry shoot mass, leaf area and percentage leaf and root tissue N, P, and K. Results of this study demonstrated that, in all trials regardless of season, N, P, or K nutrition increased bush tea fresh and dry shoot mass, plant height, number of leaves, number of branches and leaf area. Regardless of season, the optimum level of N, P and K fertilization for bush tea on growth parameters was 300 kg·ha -1 N or P and 200 kg·ha -1 for K. No significant differences in number of flowers and buds (fall and winter), stem girth, fresh and dry root mass as well as fresh and dry stem mass were obtained. Bush tea (Athrixia phylicoides) belongs to the Asteraceae family (Bremer, 1973). It is a small, pretty shrub, branched, with thin woolly stems. It also has small, dark green pointed leaves with white woolly backs and small pink daisy flowers with a bright yellow centre (Roberts, 1990). Flowers vary from pink to all shades of pink and attractive purple colour depending on soil types and geographic areas (Van Wyk and Gericke, 2000). It is a popular beverage used as herbal tea and as medicine for cleansing or purifying the blood, treating boils, headaches, infested wounds and cuts, and the solution may also be used as a foam bath. The foam bath brew can also be used as a lotion dabbed on to the boil, skin eruption or cut (Roberts, 1990). The tea infusion is also excellent for coughs and colds and as a gargle for throat infections and loss of voice. In some parts of South Africa, people drink it for aphrodisiac reasons (Mabogo, 1990). Cultural practices have a significant influence on tea growth and productivity of herbal teas (Owour, 1989; Ruan et al., 1999; Venkatesan et al., 2004). Among such cultural practices, mineral nutrition (Hilton et al., 1973; Barauh et al., 1986; Owour et al., 1990; Owour and Odhiambo, 1994); plucking (Owour et al., 2000), and irrigation (Stephens and Carr, 1991) have been widely reported to improve tea growth and maximize productivity. In mineral nutrition, the application of nitrogenous, potassium and phosphorus fertil- izers are the main normal agronomic practices and several studies have shown improvement on growth and yield (Keen and Zidenberg- Cheer, 2000; Marschener et al., 1996; Owour and Odhiambo, 1994; Owour et al., 2000), thus resulting in increasing biomass produc- tion of tea. The plant materials of bush tea are only harvested from the wild and the concept of domesticating wild plants is very important in order to avoid the natural population from becoming extinct from its native environment. Presently, the mineral nutrition on bush tea is not well established. Data are lacking on the response of N, P, and K on growth and produc- tivity of bush tea. Therefore, the present paper reports the effects of N, P, and K application on growth and development of bush tea under cultivation as influenced by season. Materials and Methods Experimental site and plant material. The study was carried out in Morgenzon, a com- mercial nursery in Louis Trichardt (23°N 50'E, 30°S17'E; alt 610m; subtropical-type climate i.e. summer rainfall and cold, dry winter). On 13 Nov. 2002, plant materials was collected from Venda (Limpopo Province) and 1500 planting materials of apical cuttings were dipped in Seradix No. 2 hormone (0.3% IBA) and established in seed trays on a mist bed. Rooted cuttings were transplanted into 1-L bags and placed in a hardening chamber for 3 months. After 3 months, planting materials were transplanted into 20-L bags. The medium was a 1 pine bark : 2 sand : 1 stryofoam bead mix (v/v), with AquaGro wetting agent (Aqua- trols, Cherry Hill, N.J) at 0.2 kg·m –3 . The initial media test chemical analyses were determined using (Hanlon et al., 1994) procedure. The EC was 0.9 dS·m -1 and pH was 4.7. The pine bark contained NO 3 -N of 1.2 mg·kg –1 , 0.1 mg·kg –1 P and 1.3 mg·kg –1 K. Experimental design and treatments. Three (N, P and K) parallel trials were conducted un- der 50% shade nets with one at each season in a randomized complete block designed with six treatments replicated 8 times. Fertilizer sources used were limestone ammonium nitrate (for N trial), single super phosphate (for P trial) and potassium chloride (for K trial) applied as post plant one week after planting in the form of granules. The treatments consisted of 0, 100, 200, 300, 400, or 500 kg·ha –1 N, P, or K. The standard nursery management applications of 1% MgSO 4 , ZnO, Microfel Fe (Fe = 29%), mono ammonium phosphate (Climax) [52% P 2 O 3 (P = 22%) and 34% K 2 O (K = 28.2%)] and urea (N = 46%) (except for N and P trial), sodium borate [Na 2 B 4 O 7 ·10H 2 O (27% boron and 18% Na)] and KCL (except for K trial) were applied twice per week as foliar sprays to supplement the rest of the elements necessary for the production of good quality tea. Data collection. At harvest, all plants per treatment per replication (fall, 30 May 2003; winter, 30 Aug. 2003; spring, 30 Nov.and sum- mer, 28 Feb. 2004), plant height (cm), number of branches, number of leaves, flowers and flower buds (fall and winter), stem girth (mm), fresh and dry root mass (g), fresh and dry stem mass (g), leaf area (measured by a LI-3100 area meter; LI-COR, Lincoln, Neb.), fresh and dry shoot mass (g), and percentage leaf and root N, P, or K content were recorded. Leaf and root tissue N content. Total N was determined using the Auto-analyser method (Technicon, 1972) on a Sanplus Segmented Flow Analysis System (Skalar Instruments, Netherlands). Leaf and root tissue P and K content. P and K were analyzed using the method by Adrian (1973). Statistical analysis. Analyses of variance were performed on data using the GLM (Gen- eral linear model) procedure of SAS version 8.0 (SAS Institute Inc., 1999). Treatment sums of squares were partitioned into linear and quadratic polynomial contrasts. Results and Discussion Nitrogen trial. Regardless of season, plant height, number of branches and leaves, leaf area, and fresh and dry shoot mass increased quadratically in response to nitrogen nutrition (Tables 1, 2, 3, and 4). Regardless of season, the optimum level of N for growth parameters was 300 kg·ha –1 . Most of the growth responses HORTSCIENCE 40(6):1898–1901. 2005. Received for publication 22 Mar. 2005. Accepted for publication 18 June 2005. The authors would like to acknowledge Morgenzon, a commercial nursery for providing the trial sites and the National Research Foundation (NRF) for financial assistance.