engleski

Mineral content and yield of lettuce in aquaponic production

Aquaponics is an integrated recirculating system that combines aquaculture and hydroponic plant production. In the period of evident climate changes and limited water resources, aquaponics presents a sustainable way of agricultural production. Considering that this kind of production is still less known in Croatia, it is necessary to study the agronomic traits and the nutritional value of vegetables produced aquaponically. The aim of the research was to determine mineral content and yield of lettuce in floating aquapon in comparison to floating hydropon. The experiment was conducted in greenhouse during spring period of 2016 at experimental station of Faculty of Agriculture in Zagreb. The aquaponic system was consisted of ponds with African catfish (Clarias gariepinus) connected with basins for lettuce (Lactuca sativa L.) production. Floating hydroponic system with a standard nutrient solution was used as a control treatment. Abiotic parameters (temperature, pH, electroconductivity, content of dissolved oxygen, ammonia, nitrates and nitrites) were measured regularly during vegetation in both growing systems. During harvest yield of lettuce rosettes was determined and samples for analysis of mineral content (dry matter, total nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, manganese and copper) were prepaired. Concentration of ammonia, nitrites and dissolved oxygen in the aquaponic system varied significantly during the production cycle, while the values of the abiotic parameters of the floating hydropon nutrient solution were stable. Among the tested production systems, statistically significant differences in the content of all minerals, except for copper, were determined. Higher content of nitrogen (5.17 % N dry weight (dw)), phosphorus (0.80 % P dw), potassium (8.37 % K dw) and iron (157.60 mg kg -1 dw), as well as the yield (4.1 kg m-2) were determined in the lettuce grown in the floating hydropon. Aquaponically produced lettuce contained higher values of dry matter (5.02 %), calcium (2.35 % Ca dw), magnesium (0.38 % Mg dw), zinc (702.12 mg kg -1 dw) and manganese (60.25 mg kg -1 dw). The optimization of water quality, considering the requirements of produced plants and fish, is the most important for sustainability and success of aquaponic production.

African catfish, dissolved oxygen, lettuce, macroelements, microelements

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