Effects of liquid extract of fish waste on growth performance of micro-propagated Water Trumpet (Cryptocoryne wendtii)

Abstract

Biological waste from fish processing and post-harvest handling is an environmental issue and the conversion of fish waste into organic fertilizer has been identified as an eco-friendly approach to address it. Therefore, this study was done to evaluate the effectiveness of liquid extract from fish waste as a liquid fertilizer (LFE) and its effects on the growth performance of the micro-propagated ornamental aquatic plant Cryptocoryne wendtii. Three levels of LFE, 0.25 gL-1, 0.50 gL-1, and 0.75 gL 1 were compared with the recommended level of inorganic fertilizer (0.5 gL-1 Albert solution) as the control for six weeks. Twenty-four micro-propagated plants were potted in individual plastic cups and plants were randomly allocated to 12 glass tanks (two pots per tank) with the respective level of fertilizer (40 L). Complete water exchange with the relevant level of fertilizer was done at two weeks intervals and, NO3−and PO4 3−concentrations of water were measured before water was renewed. In this study, measurements of initial and final plant wet weight, total plant height, stem height, rhizome height, root length, leaf length and width, leaf area, and the number of leaves and shoots were taken. Additionally, Relative Growth Rate (RGR), Leaf Area Ratio (LAR), and Net Assimilation Ratio (NAR) were calculated for plants in each treatment. These parameters were compared using one-way ANOVA. Plant wet weight, total plant height, rhizome height, leaf width, and leaf area of plants treated with 0.75gL-1 LFE showed significantly higher growth performance compared to the control. Significantly higher RGR, LAR, and NAR were reported for 0.75gL-1 LFE treatment followed by 0.5gL-1 and 0.25gL-1 LFE treatments. The results of this study revealed that liquid fish waste extracts at the concentration of 0.75gL-1 can be used as a liquid fertilizer for Cryptocoryne wendtii without compromising the growth performances when compared to the recommended level of inorganic fertilizer.