Effect of fertigation using fish production wastewater on Pelargonium x zonale growth and nutrient content

Aquaculture effluent can supply certain plant nutrients in adequate amounts. However, the nutrients present in the fish waste solution are not balanced. Mixing this effluent in an independent unit with a hydroponic nutrient solution can help to optimize conditions for the plants and minimize such drawbacks. The objective of this work was to assess the crop production and the nutritional responses of Pelargonium zonale fertigated with different percentages of fish wastewater. Five treatments were performed: 100NS, 75NS+ 25AS, 50NS+ 50AS, 25NS+ 75AS and 100AS, where AS is the fish wastewater and NS a hydroponic nutrient solution. The species used to provide the fish waste solution was tilapia nilotica (Oreochromis niloticus). The results of this assay show that: i) fish wastewater can be utilized for the fertigation of Pelargonium zonale (a short-cycle crop) as there are no differences in the leaf, stem-petiole and flower dry matter, leaf water content, leaf area, plant height and leaf color compared to Pelargonium zonale fertigated with a chemical fertilizer; ii) the application of 75NS+ 25AS accelerated flowers, shoots and leaves production. A higher percentage of fish waste solution mixed with the applied nutrient solution significantly reduces the K concentration in the nutrient solution and in the leaf; however, tilapia waste solution supplies adequate N, P and Ca nutrients to the pelargonium plants. Therefore, the reuse of fish waste solution can reduce the application rate of some inorganic fertilizers, which in turn can reduce the cost of fertilizers while preventing environmental pollution.