Effects of the Culture Medium, pH Level, and Type of Sugar on the Growth of Sphagnum cuspidatulum Müll. Hal.

Owing to habitat modifications and climate change, Sphagnum moss has gradually disappeared from many tropical areas. In Thailand, Sphagnum cuspidatulum Müll. Hal., which was one of the most abundant species in the past, experienced a significant decline in 2022. The in vitro conservation of this species in an axenic culture in the laboratory has not been attempted, and therefore our work focused on the gametophytic cultivation of S. cuspidatulum using the tissue culture technique. After collecting samples in the field, a gametophyte of S. cuspidatulum was prepared by growing the moss in a growth chamber for three months to induce shoot tip elongation. The explants were cultured for six weeks in different formulas of culture media, initial pHs of the treatments, sugar types, and sugar concentrations. The results showed that the highest dry weight was produced with the 1/6MS treatment, followed by the 1/8MS and 1/4MS treatments. Different initial pHs did not affect the dry weight or total chlorophyll content. It was also found that the pHs of all of the treatments gradually declined during cultivation to less than 3.0. When we supplemented the media with sugar, the 1/4MS treatment supplemented with 1.5% to 2% glucose had the highest dry weight. This study was the first to use MS media for Sphagnum cultivation rather than traditional media such as Knop and B5. The results demonstrated the potential of using micropropagation for the mass production and ex situ conservation of S. cuspidatulum in Thailand.