Vetiver (Chrysopogon zizanioides L. Roberty) plant growth in modified floating net cage system

Abstract

Observations were carried out on the vetiver plant (Chrysopogon zizanioides L. Roberty) that functioned as a biofilter in a modified floating net cage (KJA) system in the Cirata Reservoir, West Java, Indonesia. The plant was designed to filter the residual organics and nutrients from the fish feed residue. In this study, the vetiver was planted in 30 L containers and fed continuously with water containing fish feed residue. Observations were made once a week for 75 days, focusing on the physical growth of the shoots or tillers, roots and leaves of the plants. Parameters that affected the environmental conditions were also analysed, namely pH, temperature, turbidity, dissolved oxygen, chemical oxygen demand (COD) and nitrate. The results show that the maximum root length was 110 cm and the maximum leaf length was 140 cm. The water pH was in the neutral range of 6–8 and the temperature was stable in the range of 28-30 °C. Vetiver could decrease the COD concentration from 24–28 mg.L⁻¹ to 14–18 mg.L⁻¹. This shows that the vetiver could utilize nutrients from organic waste derived from fish feed residue and act as a biofilter in the KJA system.