Micropropagation of eucheumatoids using liquid extracts from the brown algae Ascophyllum nodosum (Fucales) and Laminaria digitata (Laminariales)

Eucheuma denticulatum and Kappaphycus alvarezii , two tropical red seaweeds, are two of the most commercially important, cultivated carrageenophytes in Southeast Asia. Their large-scale farming through repeated vegetative propagation and virtual mono-cropping has resulted in a variety of phyconomic issues. The efficacy of two European, commercial liquid extracts from the brown seaweeds, i.e., Ascophyllum nodosum (ANE), a fucoid, and Laminaria digitata (LDE), a kelp, on the direct formation of axes and survival of these two eucheumatoids was examined using tissue culture techniques. Seaweed apical sections (3–5 mm long) were cultured for 45 days, with different concentrations of ANE and LDE (i.e., 0.005, 0.05, 0.5, 1.5, and 2.5 mL L − 1 ) and compared with a control (UV-filtered seawater). Both liquid extracts improved the growth and morphogenesis of E. denticulatum and K. alvarezii in tissue culture. This study recommends a dilution rate of 0.05 mL LDE per L for E. denticulatum tissue culture resulting in a high percentage survival (i.e., 95.3 ± 0.9%), formation of direct axes (i.e., 95.3 ± 0.9%), and the longest length (i.e., 10.0 ± 0.3 mm) after a typical 45-day culture period. These data combined with the highest percentage formation of axes on day 14 (i.e., 88.0 ± 4.9%). However, 0.5 mL ANE per L is recommended for the tissue culture of K. alvarezii , given the relatively high final survival and direct axis formation (i.e., 96.2 ± 2.2%) and shoot length (i.e., 8.2 ± 0.1 mm). This study supports the application of these temperate, brown seaweed-derived extracts as phycobiostimulant enrichment in eucheumatoid micropropagation for mass production of plantlets for out-planting purposes.