Shamima Akter
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Alif Layla Bablee
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
K. M. Shakil Rana
Assistant Professor
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Mahbuba Nigar
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Zubyda Mushtari Nadia
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
M. A. Salam
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh
Aquaponics, Epsom salt, Foliar application, Root application, Beetroot
The Aquaponics Laboratory (Aquaponics Oasis), Department of Aquaculture, Faculty of Fisheries, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh
Crop-Soil-Water Management
Site selection:
The experiment was conducted at the Aquaponics Laboratory (Aquaponics Oasis), Department of Aquaculture, Faculty of Fisheries, Bangladesh Agricultural University (BAU), Mymensingh from 17th february to 18th May, 2018.
Experimental design:
The experimental design was comprised of nine sets of aquaponics unit where nine fish holding tanks (diameter 58 cm, height 45 cm) each containing 120 liter of water and nine plastic containers for vegetable growing beds (38.5 cm length, 28.5 cm width, 22 cm height) were installed.
There were two treatments (T1 and T2) with Epsom salt application (foliar spray and direct application on plant grow bed respectively) and control (T0) with no Epsom application. Each treatment (T) were applied on three separate aquaponics unit as replication (R), therefore denoted as T1R1, T1R2, T1R3, T2R1, T2R2, T2R3, T0R1, T0R2 and T0R3 Which were placed randomly.
Bed preparation for beetroot cultivation:
Plastic containers which were locally available, cheap and good quality used as beetroot culture beds (plant growbeds). Each container (38.5 cm length, 28.5 cm width, 22 cm height) was cut longitudinally 1.27cm inch below from the upper surface to make it a bed, cleaned with detergent, rinse with clean water for 3 to 4 times and sun-dried before use. A hole was made above 0.5 inch from the bottom to facilitate clean water passage from the beetroot bed to the fish tank. Each grow bed was filled with brick lets of 2-5 cm sizes as plant growing substrates. The plastic containers were placed on a wooden structure for convenient management.
Planting beetroot saplings:
For the production of beetroot saplings first, the seeds were soaked for 24 hours. Then these were replaced to a plastic bucket containing 50% cocoa dust and 50% vermicompost and covered with paper. Before that a pore was created into the plastic bucket 0.5 inch above the bottom for emergency water exit. After germination 2 saplings were planted in two opposite corners of each growbed.
Application of Epsom salt:
Locally available Epsom salt was collected and prepared for application in T1 and T2. In T1, 5% epsom salt was applied as foliar spray on beetroot plants of each replication (R). Foliar spray for each plant growbed was prepared by dissolving 5 g of Epsom salt in filtered water to make the final volume 100ml and sprayed on plants fortnightly. Whereas, 5g of epsom salt was applied directly on each growbed fortnightly in T2. T0 was control, therefore no Epsom was supplemented. The concentration of Epsom salt was selected according to Kristek et al., 1997.
Fish tank preparation:
Nine fish holding tanks (diameter 58 cm, height 45 cm) with the volume of 90 L of water were used for fish culture. The tanks were prepared by washing, drying, setting up pipes, filling up with water. The tanks were brought from local market. At first tanks were uncovered and then these were washed with disinfectant to remove chemicals if any. An 18 watt submersible pump for watering the vegetables and one air pump with two air stones for oxygen supply were set in each aquaponics unit.
Stocking and rearing the fish:
Monosex tilapia (Oreochromis niloticus) were collected from a renowned hatchery. During transportation oxygenated polythene bags that contained 2/3 oxygen and 1/3 water was used. Acclimatization helps to minimize stress of fingerlings and to adapt with the differences of water temperature, pH, and oxygen between the transported bag and the fish tank water. For acclimatization, the polythene bag containing fish was kept in fish tank for one hour to reduce the temperature difference between polythene bag and fish tank. After acclimatization the bag was untied and created current by hand so that the fish can move freely into the tank. The fish which could not swim freely against water current was discarded. Ten fish were stocked in each tank containing 90 L of water. Fish were stocked after thirty days of beetroot plantation to allow beetroot sapling grow enough to support the recirculation process in aquaponics.
Fish and vegetable sampling and harvesting:
Fish and vegetables were sampled fortnightly. During each sampling, 10% fish of each tank (each replication) were caught randomly with a scoop net and individual length-weight was measured with an electronic compact balance and wooden measuring scale to ascertain fish growth performance. Number of leaves, leaf area, length and weights of plants and roots were also recorded during each sampling. All data were recorded in a notebook. After recording length and weight, fish were released in the respective tank. After 90 days of the experiment, fish and beetroots were cropped on the day of final harvest.
Water quality parameters:
Physicochemical parameters of tank water were measured to know the suitability of fish culture. Temperature, DO (dissolved oxygen) and pH were measured every 7 days interval. Electric conductivity (EC), carbonate (CO3), hydrogen carbonate (HCO3), potassium (K), total nitrogen (N), sulfur (S) and sodium (Na) content of aquaponics water were also measured at monthly intervals. The tests were done in the Humboldt Soil Testing Laboratory, Soil Science department, Bangladesh Agricultural University.
Data processing and analysis:
The data were processed for analysis using "Microsoft Excel 2010". The collected data were summarized carefully before the final tabulation. Data were analyzed by using one-way analysis of variance (ANOVA) and Duncan’s new multiple range test (DMRT). R-Stat software was also employed to visualize the significance of the treatments. Final results have been depicted in tabular and graphical forms.
Asian J. Med. Biol. Res. 2020, 6 (1), 56-66; doi: 10.3329/ajmbr.v6i1.46479; ISSN 2411-4472 (Print) 2412-5571 (Online)
Journal