Growth performance of roselle (Hibiscus sabdariffa L.) in aquaponics and determination of the optimal stocking density of Nile Tilapia maximizing its productivity

Abstract

This study was performed to evaluate productivity of roselle (Hibiscus sabdariffa) in aquaponics and determine the optimal fish stocking density which maximize its growth performance. It was conducted with Nile Tilapia Oreochromis niloticus (30.4±4.5 g and 6.5±1.2 cm) using fifteen plant/m2 and five levels of fish stocking density (3 kg.m-3, 6 kg.m-3, 9 kg.m-3, 12 kg.m-3 and 15 kg.m-3). After 45 days, the plants were examined with respect 18 growth and productivity variables. The results obtained show that plants with higher fish stocking density showed better growth performance as plant biomass (2736 ± 34.9 g/unit), plant height (95.0±7.1 cm/plant), number of leaves per plant (89.4±6.5), fresh leaves biomass (932.9± 23.8 g/plant), leaf area (35.8 ± 4.3 cm2/plant) and plant growth rate (115.11± 9.4%) observed with plants of 15 kg.m-3 for plant biomass, plant height, number of leaves, leaf area, and plants of 12 kg.m-3 for leaves biomass, plant growth rate and root weight. The linear regression analysis showed a highest correlation between fish stocking density and plant height (R² = 0.9693), leaves number (R² = 0.9209), leaf weight (R² = 0.878), plant weight (R² = 0.956), leaf length (R² = 0.8945) and leaf width (R² = 0.9234). Relationships between leaf area and leaf number per plant is also very high (R² = 0.9508). Polynomial regression analysis showed that the optimal fish stocking density maximizing roselle productivity is 14.1 kg.m-3 for leaf number and 13.0 kg.m-3 for leaf area.