Variation of N and P Fertilizer Combination Ratios on the Growth and Morphology of Caulerpa racemosa in a Closed System Cultivation

Caulerpa racemosa lives in waters with sand, coral and mud substrates, and is widely used by coastal communities as food. The purpose of this study was to evaluate the effect of nitrogen (N) and phosphorus (P) fertilizers using Urea (NH2CONH2) and SP-36 (P2O5) with different concentration variations on the growth and morphology of C. racemosa. This research was conducted at the Brackish Water Aquaculture Fisheries Center (BPBAP) Takalar. C. racemosa was maintained in basin containers equipped with a water circulation system in each container. This research design uses a complete randomized design (CRD) with 5 treatments and 3 replicates. The treatment used were the following ratios of Urea and SP-36 fertilizer: A (100 : 0%), B (75 : 25%), C (50 : 50%), D (25 : 75%), and E (0 : 100%). The results indicate that the addition of nutrients to the closed cultivation medium using a combination of N and P fertilizers resulted in the highest growth rate of 2.2% per day in treatment C and the lowest growth rate of 1.64% per day in treatment E. While the stolon diameter and rachis length showed no significant differences, the distance between rachises in treatment B was significantly different (P<0.05) compared to other treatments. These data are useful for considering the optimal combination of urea and SP-36 fertilizers for the cultivation of C. racemosa.