Viện Nghiên cứu Hải sản

The Research Institute for Marine Fisheries (RIMF) has successfully completed the Ministry-level scientific and technological task "Research on the application of high technology in the production of seedlings and cultivation technology for high yield and quality carrageenan in Central Vietnam." This has led to the improvement of tissue culture technology, development of rapid propagation processes, and intensive cultivation models for Kappaphycus alvarezii. The results have produced a large number of high-quality, genetically uniform seedlings, significantly reducing production time. The seedlings introduced into intensive cultivation show increased growth rates, and the quantity and quality of carrageenan in commercial seaweed have improved.

Value of Kappaphycus alvarezii

Kappaphycus alvarezii (Doty) Doty ex P.C. Silva, commonly known as "carrageen moss," is a tropical seaweed belonging to the red algae (Rhodophyta) class. It has a high carrageenan content and is widely cultivated as a primary raw material in the food, cosmetics, pharmaceuticals, and organic fertilizer industries. Over the past 30 years, carrageen moss has been successfully introduced and reintroduced into non-native ecological regions in more than 20 countries. Currently, it is primarily grown in Asian countries such as Indonesia, the Philippines, Vietnam, and Malaysia to produce relatively pure carrageenan. Madagascar, India, Tanzania (Zanzibar), several Central/Southern Pacific islands (Kiribati, Fiji, and the Solomon Islands), and East Timor are also significant producers of this seaweed. Kappaphycus alvarezii exhibits rapid growth, with biomass potentially doubling within 15-30 days. Harvesting time can range from 6 to 12 weeks, depending on cultivation conditions. Typically, after 8 weeks, carrageen moss can reach optimal quality indicators (biomass yield and carrageenan content as well as gel strength), making it suitable for harvesting. Currently, the demand for raw materials for carrageenan processing products is increasing, driving the industrialization and commercialization of this seaweed species. In addition to its economic value, carrageen moss plays a significant role in absorbing nutrients, heavy metals, and some pollutants in marine environments. Thus, coastal cultivation of carrageen moss not only provides economic benefits but also contributes to environmental improvement.

Refinement of Tissue Culture Technology and Genetic Restoration of Kappaphycus alvarezii

The Research Institute for Marine Fisheries (RIMF) is a pioneer in the research and genetic restoration of Kappaphycus alvarezii, achieving significant accomplishments. From 2013 to 2017, the Institute conducted studies on the propagation of Kappaphycus alvarezii using tissue culture techniques, proposing a tissue culture process with a rate of callus formation exceeding 70%, good callus at 40-60%, and the capability to regenerate into seedling fragments.

Figure 1. Process of Producing High-Quality Kappaphycus alvarezii Seedlings through Callus Culture and Embryo Development.

A: Culture on agar plates
B: Formation of callus
C: Formation of micro-shoots from embryos
D and E: Morphology of tissue-cultured Kappaphycus alvarezii
F: Adapted tissue-cultured Kappaphycus alvarezii in the laboratory

The improved process established by the Institute shortened the seedling production time from 260 days to less than 180 days, while also increasing efficiency and reducing production costs. Agitation speed was increased from 100 to 150 rpm, achieving a regeneration rate of 97%, with a 1.5-fold increase in the number of shoots. The use of PES medium for cultivating seedlings has been studied and replaced with inorganic nutrient media with an N:P ratio of 10:1, leading to higher growth rates and lower costs. Adapted seedlings have a survival rate exceeding 90%. After adaptation, seedlings are transferred to nursery stages in mesh cages, achieving survival rates above 95% and average growth rates of over 3% per day. Through tissue culture methods, over 5,690 high-quality Kappaphycus alvarezii seedlings have been produced, enabling large-scale development of F1 plants through direct shoot regeneration, serving intensive cultivation models and supplying high-quality seedlings for mass production.

Figure 2. Rapid Propagation of Kappaphycus alvarezii via Direct Shoot Regeneration from Tissue-Cultured Seedlings:

A: Laboratory rapid propagation of tissue-cultured Kappaphycus alvarezii
B: Tissue-cultured Kappaphycus alvarezii reaching a size (2 cm) for intensive cultivation models

Figure 3. Nursery of Rapidly Propagated Kappaphycus alvarezii for Intensive Cultivation Models:

A: Kappaphycus alvarezii seedlings grown naturally
B: Kappaphycus alvarezii reaching input size for intensive cultivation models

Additionally, the project has refined the rapid propagation process through direct shoot regeneration, producing numerous tissue-cultured Kappaphycus alvarezii seedlings on a large scale, ensuring quality inputs for intensive cultivation models from high-quality Kappaphycus alvarezii seeds. The model (0.5 ha) achieves yields of ≥40 tons/ha/season (3-4 months); carrageenan content reaches ≥40% of dry biomass, with gel strength ≥500 g/cm², meeting technical specifications and product outputs. This model demonstrates the success of producing high-quality Kappaphycus alvarezii seedlings through tissue culture and direct shoot regeneration. The research results can be applied to develop commercial Kappaphycus alvarezii cultivation models in Central Vietnam and promote the development of the seaweed industry in Vietnam.

References

[1] E.I. Ask, A. Batibasaga, J.A. Zertuche-González (2003), Three decades of Kappaphycus alvarezii (Rhodophyta) introduction to non-endemic locations”, Proceedings of the 17th International Seaweed Symposium, pp.49-57.

[2] R. Campbell, S. Hotchkiss (2017), Tropical Seaweed Farming Trends, Problems and Opportunities: Focus on Spinosum and Cottonii of Commerce, Springer, pp.193-206.

[3] C. Gavino, J. Trono, (1992), “Eucheuma and Kappaphycus: Taxonomy and cultivation”, Bulletin Marine Science, 12, pp.51-65.

[4] R.D. Villanueva, J.B. Romero, M.N.E. Montaño, et al. (2011), “Harvest optimization of four Kappaphycus species from the Philippines”, Biomass Bioenergy, 35, pp.1311-1316.