Nitrogen, Phosphorus, and Potassium Nutrition Increases Growth and Total Polyphenol Concentrations of Bush Tea in a Shaded Nursery Environment

Abstract

The objective of this investigation was to determine the effects of simultaneous applications of nitrogen (N), phosphorus (P), and potassium (K) nutrition on growth and chemical analysis of bush tea (Athrixia phylicoides). Four consecutive trials were conducted at Morgenzon (Louis Trichardt, Limpopo Province, South Africa), a commercial nursery, one at each season (autumn, winter, spring, and summer) under 50% shade. Treatments comprised three levels of N (300, 350, 400 kg·ha−1), three levels of P (250, 300, 350 kg·ha−1), and three levels K (150, 200, 250 kg·ha−1). The experimental design was a 3 × 3 × 3 factorial experiment arranged in a randomized complete-block design with four replications. Parameters recorded were plant height, number of branches and leaves, fresh and dry stem weight, fresh and dry root weight, stem girth, fresh and dry shoot weight, leaf area, and percent concentration of leaf and root tissue N, P, K, and total polyphenol concentrations as influenced by season in a shaded nursery environment. Treatment combinations of N and P at rates of 300 kg·ha−1 and K at 200 kg·ha−1 increased fresh and dry shoot weight, number of leaves, leaf area, and concentration of total polyphenols. Other treatments did not consistently affect concentrations of leaf N, P, or K during the study period, although the treatment that received combinations of N and P at rates of 300 kg·ha−1 and K at 200 kg·ha−1 always had the highest concentrations of leaf N, P, and K and lowest root N, P, and K concentrations. No differences in plant height, number of branches, number of flower buds (autumn and winter), stem girth, fresh and dry root weight, and fresh and dry stem weight due to treatment combinations were observed.