1. Hypothesis: If Coriandrum sativum and Ocimum basilicum grow in an aquaponics tank with Carassius auratus, then basil will have a higher % increase in biomass.
2. Literature:
Review: Basil has a higher yield (mass) when grown in aquaponics than hydroponics on conventional field basil. This was evidenced by a 14% higher yield and consistently higher height measurements (Monroe, Day). However, cilantro did not grow well in an unrelated floating bed aquaponics experiment. This was characterized by yellow leaves and dark marks in the roots, which may be signs of a fungal infection (Silva et. al).
a) Selection of plants for soil-less systems is critical. Basil (Ocimum basilicum L.) is an annual herb that is commercially important and both fresh and dried leaves are used for culinary purposes (Chalchat and Ozcan, 2008). Basil is considered a medicinal herb (Ahmed et al., 2014) for its diuretic and stimulating properties and also used in perfume compositions (Nguyen et al., 2010). Basil is suitable for soilless production, and several studies have used basil as aquaponic or hydroponic crop (Rakocy et al., 2004; Roosta, 2014; Mangmang et al. (2016)). Basil responds with better yield under soilless systems than conventional systems. Rakocy et al. (2004) reported that aquaponic basil produced higher yield (1.8 kg m−2) than field basil (0.6 kg m−2). However, no studies have compared aquaponics and hydroponics systems for basil production.
Plant growth and yield were higher in aquaponic basil (AqB) than in hydroponic basil (HyB). The basil mean plant height at harvest was 14% higher in AqB (89.9 cm ± 4.5) than in Hyb. (78.7 cm ± 3.9) (Fig. 1). Weekly height measurements also indicated a consistently higher growth pattern for AqB compared to HyB (Fig. 2). Both fresh and dry biomass yields were higher in AqB than in HyB. AqB (150.2 g ± 18) generated 56% more fresh mean harvest weight than HyB (96.6 g ± 10.4) (Fig. 3). Corresponding mean dry weight for AqB (15.9 g ± 2) was 65% higher than HyB (9.6 g ± 1) (Fig. 4).
APA Reference: Saha, S., Monroe, A. and Day, M. (2018). Growth, yield, plant quality and nutrition of basil (Ocimum basilicum L.) under soilless agricultural systems. [online] Science Direct. Available at: https://www.sciencedirect.com/science/article/pii/S0570178316300288 [Accessed 12 Jan. 2018].
b) In aquaponics, Kotzen and Appelbaum [28] report poor coriander growth in an aquaponic system using fresh and brackish water in a floating bed technique system. However, in our case, in the COR treatment the cause of the poor plant growth was the disease which can be associated with a fungal infection by fungi of the genus Rhizoctonia or Pythium, as indicated by symptoms of poor growth, yellow leaves, and dark marks in the root [29,30].
APA Reference: Silva, L., Gasca-Leyva, E., Escalante, E., Fitzsimmons, K. and Lozano, D. (2015). Evaluation of Biomass Yield and Water Treatment in Two Aquaponic Systems Using the Dynamic Root Floating Technique (DRF). 7th ed. [ebook] MDPI, p.15394. Available at: https://pdfs.semanticscholar.org/a614/c5be9fc7185e198e25c5eb7185a832eead05.pdf [Accessed 12 Jan. 2018].
3. Independent variable: Species of plant (Coriandrum sativum and Ocimum basilicum)
4. Dependent variable: % increase in biomass of dried leaves (%). Additionally, height (mm) will be recorded after germination.
5. Control variables: Distance from light fixture, color of light (red and blue LED), water temperature, number of seeds
6. Experimental group: Net pots with Coriandrum sativum, Net pots with Ocimum basilicum
7. Control group: Net pots with hydroton
8. What unexpected challenges have you encountered thus far? Our ammonia levels are in the "danger" zone. This is alarming considering ammonia was "stressful" just 4 days before. This is most likely the result of increased pH.
9. How will you know your experiment is a success?
We will know if our experiment is a success if the growth rates of the basil and cilantro plants in our experimental group differ from our control group and if basil grows more quickly than cilantro. Growth rate will be recorded by dry biomass, % increase in biomass, and height. This will support our hypothesis that basil will experience a greater % increase in biomass than cilantro. Greater growth in basil means it is the more quickly growing herb and is more marketable for aquaponics farming. This also means more energy is taken in by the plant(s) than released.
10. How your experiment addresses energy dynamics
Our experiment addresses energy dynamics because there is a constant energy cycle throughout the tank. The fish provide nutrients for the plants (after bacteria converts the fish waste to be usable for the plants). While the plants are taking the nutrients from the fish waste, they are also helping to keep the water clean of nitrates. Through photosynthesis, the plants are able to add additional oxygen to the water as well. The plants and fish both benefit from each other, allowing both to grow and survive. We will be able to tell that the plants grew through the biomasses and that fish survived by whether or not they are still living. Our net energy should be increasing because of added energy (fish food) in the system, allowing all species of organisms to live.
11. Before picture (left) vs After (right)