## 4 Materials and Methods
### Greenhouse Experiment  
The experiment was conducted in a greenhouse on the Bellville campus of the Cape Peninsula University of Technology (CPUT). Plants were cultivated using aquaponic and hydroponic techniques. For the hydroponic system, 4-week-old rooted seedlings of _H. odoratissimum_ were transplanted into 23 cm diameter pots containing a substrate mix of two parts pine bark, one part perlite, and one part vermiculite. Fifteen replicates of _H. odoratissimum_ seedlings were used. The plants were watered daily using 400 mL of deionized water and supplied with Nutrifered fertilizer (Starke Ayres Pty. Ltd., Cape Town, South Africa), consisting of the following ingredients: nitrogen (65 mg kg\({}^{-1}\)), phosphorus (27 mg kg\({}^{-1}\) ), potassium (130 mg kg\({}^{-1}\)), calcium (70 mg kg\({}^{-1}\)), copper (20 mg kg\({}^{-1}\)), sulfur (75 mg kg \({}^{-1}\)), boron (240 mg kg\({}^{-1}\)), magnesium (240 mg kg\({}^{-1}\)), and zinc (240 mg kg\({}^{-1}\)). The fertilizer was mixed with deionized water at a dosage of 10 g/5 L. Each plant received 100 mL of the nutritional solution fortnightly, with a pH of 6.5 and an EC of 2 mS cm\({}^{-1}\), using Milwaukee EC 50 and pH 55 kits supplied by Spraytech Pty. Ltd., Cape Town, South Africa). A recirculating aquaponic system was used in the aquaporin system. The system consisted of a fish tank containing a pump and plant grow beds (four black 50 L plastic containers with perforated lids to fit the net pots). The aquaponic system had four fish tanks containing 400 L of water each and a submersible pump that pumped the wastewater (nutrient-rich water) from the tank to a grow bed through a PVC pipe. The grow bed had a deep culture design. It consisted of two black 50 L plastic containers with a perforated lid to fit the net pots. Fifteen _Helichrysum_ seedlings were transplanted into net pots containing a mixture of perlite and coco coir (50:50 ratio) as substrate. The plants were watered from the bottom through the drain holes in the net pots immersed in the nutrient-rich water pumped from the fish tank. Recycled water from the grow bed returned to the fish tank. Thus, recycling of the nutrient water was continuous. An air pump (Regent 7500) connected to an air stone using tubing was used to improve dissolved oxygen at 150 L/H in the fish tank. Each grow bed had 15 seedlings fed from the same fish tank. Ten-to-fifteen-centimeter Goldfish fingerlings (_Carassius auratus_) and fish food (Koi and Goldfish powder, small pellets) supplied by Stodels Nursery Pty. Ltd., Doncaster Road, Kenilworth 7708, Western Cape, South Africa, were used in this study. Twenty Goldfish (_Carassius auratus_) were placed in each tank (1000 L capacity). The constituents of the fish meal were maize, rice, wheat, wheat germ, dehulled soybean meal, lysine, methionine, lime, dicalcium phosphate, vitamins (A, D, E, K, BI, B2, B6, B12), biotin, folic acid, inositol, minerals, colorants, spirulina, immune stimulants, vegetable fats, natural antioxidants, and betaine. The fish were fed twice daily at 08:30 am and 4:00 pm. The aquaponic setup was replicated four times. The experiment lasted for 6 weeks. At the end of the experiment, plant height (cm) and fresh and dry weights (g) of aquaponically and hydroponically produced plants were recorded. The growth parameters of field plants were not assessed because the plants were already cultivated and established on the premises of the Bellville campus of CPUT before the commencement of the study. The harvested plant materials were used for tissue nutrient and secondary metabolite content analysis, and were screened for antifungal activities. The leaves of randomly selected field \(H\). _odoratissimum_ plants were harvested, secondary metabolites were characterized, and antifungal activity was assayed. The greenhouse conditions were 15-26 \({}^{\circ}\)C and 74% RH. The EC level of the nutrient solution in the fish tank was 0.8 mS cm\({}^{-1}\) and the pH was 6.3.