Aquaponics using Asian leafy vegetables - potential and challenge
Aquaculture became worldwide an integral part of the food production. In the same way different hydroponic systems are widespread in many countries. Asian leafy vegetables are cultivated in particular in the water culture system 'nutrient-film-technique' (NFT). A combination of the two cycles in an aquaponic system seems to be reasonable. This technique becomes more and more important for the food production and has an increasing popularity, even though the system is not methodologically sound and completely scientifically investigated. Therefore, three experimental series were conducted in order to investigate open and closed process water cycles, using parallel aquaculture and NFT system, as well as aquaponics, where the fish species tilapia (Oreochromis niloticus) was utilized. Three leafy vegetables were used in different experiments the South-East Asian herbaceous vegetable water spinach (Ipomoea aquatica), leaf mustard (Brassica juncea integrifolia) and water celery (Oenanthe javanica); all are suitable for water culture systems. Plant growth and development were investigated in both systems, in the hydroponic NFT and in an aquaponics. In the NFT system, mineral nutrient solution was used, whereas in the closed aquaponic system the plants were fertilized only with the fish water. The leafy vegetables were cultivated between four and seven months. In the end, the plant height and biomass were measured and the contents of chlorophyll a and b, ascorbic acid and carotene were analyzed. In the nutrient solution, respectively, the process water the EC and pH-value, as well the oxygen contend were measured weekly. There were no significant differences in plant development between the two cultivation systems, when water spinach was used. The yield of leaf mustard was much lower in the aquaponics in comparison to the NFT system. The plant development of water celery was at the beginning very slowly, later on the development of the plants was better in aquaponics. The tilapia development was better in the closed system as aquaponics in comparison to the aquaculture system. In general, it can be concluded that the closed aquaponics system has a good potential for vegetable and fish production if suitable plants are used. Furthermore, the aquaponics should be deeper investigated in order to get stable chemical and microbiological conditions. There is a potential for optimisation.
Böhme, M.H., Dewenter, M. and Gohlke, A. (2020). Aquaponics using Asian leafy vegetables - potential and challenge. Acta Hortic. 1273, 115-122
Asian vegetables, tilapia, Oreochromis niloticus, closed water culture, NFT