Tiger shrimp farming in rice-fish farming system using salinity-tolerant rice lines

Rice-fish farming for tiger shrimp, Penaeus monodon, is a system in the rice fields, carried out simultaneously with rice plants on unproductive land due to seawater intrusion, optimizing land potential and increasing farmers' income. This study aimed to obtain rice lines that have salinity tolerance to be cultivated in an integrated manner with P. monodon. The research was conducted in Marana experimental pond, Maros Regency, from March to August 2019. It was carried out on 5,000 m2 pond rice field, which was idle due to brackish water intrusion. Evaluation experiment of the rice strains was arranged in a randomized block design with four repetitions in 4x5 m2 plot size. The test material consisted of 12 rice lines (IRIT184 and HHZ 14-SAL19-Y1) and 2 comparative varieties originating from the Indonesian Center for Rice Research (ICRR). Then, 21-day-old seedlings were planted with a spacing of 25x25 cm. The field for the strain test was in the middle of the pond, surrounded by an irrigation channel with a size of 8 m, delimiting the tiger shrimp farm. The size of the basins for each block was 650 m2. Stocking density treatments for tiger shrimp are 2 individuals m-2 or 1,300 individuals plot-1 (treatment A) and 4 individuals m-2 or 2,600 individuals plot-1 (treatment B). The specimens have been previously adapted to low salinity (±5 ppt). The results after 70 days of maintenance showed that the final weight, survival and production obtained in treatment A were 13.95 g individual-1, 54.96%, and 154.80 kg ha-1, and in treatment B there were 13.45 g individual-1, 51.05%, and 278.22 kg ha-1, respectively. The final weight and survival rates between treatment A and B were not significantly different, but the production of P. monodon between treatment A and B was significantly different. The results of the evaluation on 14 rice lines showed that there were 2 rice lines that were able to adapt to high-salinity land (with a conductivity of 10.21 dS m-1), but were not able to provide grain yield due to high panicle sterility. The results of the study indicate the need for farming technology intervention in order to increase the productivity of rice-fish farming and to obtain an optimal rice yield.