Growth of the Aquatic Plant Southern Naiad in Varying Percentages of Sand and Controlled-release Fertilizer

Abstract

Native aquatic plants are important to maintaining a balanced ecosystem, but they often are displaced by exotic invasive plant species. The research on the control and growth of the invasive aquatic species hydrilla (Hydrilla verticillata) using sand substrates and controlled-release fertilizers (CRF) provides a potential production technique for other aquatic plants. We questioned if we could use hydrilla production techniques to grow southern naiad (Najas guadalupensis), a Florida-native aquatic plant that is often mistaken for hydrilla. We grew southern naiad cuttings in containers filled with 100:0, 75:25, 50:50, 25:75, or 0:100 coarse builder’s sand and sphagnum moss (by volume). Before planting, containers were fertilized with 0, 1, 2, or 4 g·kg−1 CRF (15N–4P–10K). Containers were submerged in large storage tubs filled with rainwater and grown for 8 weeks. Southern naiad shoot dry weight was greater in the 100% sand substrate than that in the 0% sand substrate. Substrate electrical conductivity (EC) levels were greater in the 0% sand with no difference among the other substrates. Shoot and root dry weight of plants fertilized with 1–2 g·kg−1 CRF were greater than 0 or 4 g·kg−1 CRF. Substrate EC also increased as fertilizer rate increased, with the highest EC observed at 4 g·kg−1 CRF. Based on our results, we would suggest growing southern naiad in substrates with 100% sand and fertilized with 1–2 g·kg−1 CRF.