Plantlets directly developed from secondary phyllodes of Sargassum siliquosum J. Agardh: Implication for seedling production during the off-reproductive season

Abstract

Development of plantlets was observed from excised secondary phyllodes of Sargassum siliquosum within a two-week period under culture conditions of 20 °C ambient temperature, 26 °C seawater temperature, 200 μmol photons m−2 s−1 light intensity, 12:12 L:D photoperiod, pH 8, and 35 psu salinity. The plantlets developed along the entire margin and both surfaces of the phyllode. Initially, small protuberances of 57.0–76.21 μm diameter were observed to develop on the surfaces that ultimately developed into plantlets with rhizoids however, no protuberances were observed along the margin of the phyllodes. These plantlets were separately cultured under similar environmental conditions except at 40 μmol photons m−2 s−1 light intensity on different substrata viz. clay panels, sponge, and cotton-mixed nylon. Among these substrata, the maximum attachment of plantlets was observed on sponge substrate followed by clay panels, and least on cotton-mixed nylon. Approximately 1427 plantlets developed on a single phyllode. These plantlets could be used as a source of planting materials during the off-reproductive season of Sargassum.