The seaweed, Kappaphycus alvarezii, is the most widely cultivated commodity in Indonesia. The problem currently faced is seedling availability due annual seasonal variations such as heavy flooding This paper presents a study aimed at solving seedling scarcity: the first based on cultivating tissue-cultured seedlings in encircling tanks. The aim of the study was to determine the effect of different initial weight on growth and carrageenan yield of K. alvarezii using tissue – cultured seedlings. This research was conducted from March to June 2019 in the Shrimp Hatchery, Kendari, Indonesia. This study applied three treatments based on different initial weight and five replications. The treatments were 5g, B: 10g and 15 g initial weights (IW). The results showed that the daily growth rate (DGR) of all treatments tended not to differ significantly but the DGR of 5-g IW tended to be higher than those of the other two treatments. The means of DGR were 3.76±0.54%/day, 3.30±0.46%/day, and 2.84±0.27%/day for 5-, 10-, and 15-g IW, respectively. Healthy rates of all treatments were 90.28%, 94.45% and 87.47% for 5-, 10- and 15-g IW. The ratio of fresh weight (FW) and dry weight (DW of 5-, 10-, and 15-g IW were 9.51:1, 9.54:1, and 9.56:1, respectively. The ratio showed no significant differences among treatments. Furthermore, for carrageenan yield, 15-g IW treatment showed the highest yield (37.05±2.18%), but had no significant differences from the other two treatments. Furthermore, all water quality parameters, temperature, salinity, DO, pH, nitrat, phosphate and turbidity were within the normal range for cultivating the seedlings. In conclusion, 5-g initial weight is a prominent weight suitable to be used in cultivating the seedlings in the encircling tank.

Monitoring program is very important to evaluate the growth and performance of the seaweed K. alvarezii cultivated in the coastal areas. However, the program are rarely to be done in Indonesia continuously. In SE Sulawesi, tissue-cultured seedling are already been used by the seaweed farmers. The aims of this study were to evaluate the third period of growth monitoring program based on daily growth rate (DGR) and ratio of final wet weight and dry weight using tissue-cultured seedlings of the seaweed. This study was conducted in Bungin Coastal Waters, South Konawe. The result showed that the mean DGR of the seedlings were 7.01±0.63%.day−1 and significantly higher (p<0.05) than the two previous monitoring years (2017 and 2018). Ratio of final dry weight: wet weight was 9.42:1 and this ratio was also higher than the two previous years. In the present study, the epiphyte infection of Sargassum polycystum and an unidentified moss were also found. In conclusion, tissue-cultured seedling show good quality even though they have been used as seedlings for four years continuously.

Acadian Marine Plant Extract Powder (AMPEP) is a commercial organic fertilizer extract from brown seaweed, Ascophyllum nodosum. This study aimed to examine the effect of different concentrations of AMPEP extract on K. alvarezii “Kulisusu” seedlings. We investigated the daily growth rate (DGR), ratio of wet weight and dry weight (FW: DW ratio), and the survival rate of seedlings in encircling tanks. Concentrations of AMPEP used in this study were 0.2, 0.4, 0.6, 0.8, 1.0 g L-1 at 30 min immersion time and without AMPEP as control for a 1-month cultivation period. The results showed that the 0.2 g L-1 of AMPEP showed higher DGR in 6-18 days of culture period (3.43-4.25%/day), the 0.6 g L-1 was higher in the 24 days culture period (3.50%/day), and the 0.8 g L-1 concentration was higher in the 30 days of culture period (3.76%/day). For FW: DW ratio, 0.2 g L-1 of AMPEP concentration showed the highest ratio (8.73:1) and was significantly different from the other treatments (p<0.05). In addition, all treatments showed a high survival rate (>93.33%) with minor variation amongst the treatments (p>0.05). The results concluded that using 0.2 g L-1 of AMPEP in encircling tanks was suitable for seedling development.