Water use and the nutritional water productivity of bush tea (athrixia phylicoides DC).

Abstract

Bush tea (Athrixia phylicoides DC.), is a naturally growing South African herb. It is highly valued for its medicinal attributes and the potential of herbal tea industrialization could help to mitigate water scarcity challenges. Nevertheless, comprehensive investigations into the water utilization, nutritional water productivity, and cultivation of bush tea remain unexplored. Hence, the study’s primary objective was to assess how bush tea elucidates its development, how much water it uses and the quality attributes when cultivated in contrasting environments. Studies on water utilization, Nutritional Water Productivity (NWP) and of bush tea have not yet been explored. The study was undertaken during the year 2022 and 2023 growing seasons. A Complete Randomised Block Design (CRBD) was used, consisting of three water regimes, viz. 100%, 30% and the control (stress and rainfed) of the crop water requirements, replicated three times. The growth, development and productivity were measured weekly at budding stage, while Water Productivity (WP) and yield assessments were carried out at harvest. Thereafter, the concentration of micro and macronutrients was then analysed, and bush tea leaves were freeze-dried to determine the biochemical analysis. The results derived from Water Productivity (WP) and Nutrient Content (NC) measurements were used to determine the Nutritional Water Productivity (NWP). Under a controlled environment, the findings indicated that the 100% ETa water treatment yielded a higher crop output (95.62 kg.ha-1) compared to the 30% ETa water treatment (60.61 kg.ha-1) and the control (12.12 kg.ha-1). Similarly,WP was more favorable under 100% water treatment in comparison to the 30% water treatment. Based on the mean values, the highest (NWP_Ca, Cu, Fe, Mn &Zn) was attained under a 30% ETa water treatment which was significantly higher than the 100% ETa water treatment and stress (control) of the crop water requirements. Similar to the controlled environment experiment, the 100% ETa water treatment yielded more crop output (259.1 Kg. ha -1) under field conditions, compared to the 30% ETa water treatment (171.2 kg. ha -1) and control (stress) (68.2 kg. ha -1). The bush tea leaf extracts were shown to be phytochemically rich, with a variety of physiologically active metabolites that were distributed differently within each water application. In conclusion, bush tea thrives well under limited water application and stress conditions, and that its yield is satisfactory, without compromising its nutrients across the varying water regimes. Consequently, NWP in bush tea cultivation serves as a valuable indicator of its potential contribution to nutritious food in water shortage areas. Additionally, the study's findings also emphasized different kinds of metabolites, including a variety of

terpenoids, chlorogenic acids, lipids, and flavonoids. Under different water levels and constrained areas, this research also decoded newly formed metabolomes of bush tea for the first time. As a result, the study reveals new knowledge that will be valuable to other researchers working on the domestication and cultivation of bush tea. Additionally, it seeks to improve the economic security of rural communities by increasing access, availability, utilization, and stability of bush tea supply. The study primarily concentrated on how the influence of varying water regimes affect bush tea growth productivity, NWP, and the phytochemicals of bush tea plant species. Keywords: Herbal tea, growth development, water regime, water use efficiency, phytochemicals, molecular network, yield, nutrient content