In vitro regeneration of hybrid Dendrobium sect. Spatulata through pseudobulb segment culture

Resumo

The low rate of Dendrobium regeneration through seed culture is a significant limitation of mass propagation development in new hybrids. An efficient protocol of in vitro regeneration through pseudobulb segment culture has been established for Dendrobium ‘Danny Dame’. Leaves and roots of seven-month-old seedlings were detached from the pseudobulb. Unsegmented pseudobulb and segments of apical, medial, and basal excised from seedlings. The four types of explants were cultured on Murashige and Skoog (MS) basal medium supplemented with different combinations of 1-naphthaleneacetic acid (NAA) and 6-benzyl amino purine (BAP). The highest number of shoots was observed in 1 mg L^-1 BAP and 0.1 mg L^-1 NAA using unsegmented pseudobulb explant after 2 months of culture. The unsegmented pseudobulb had a higher survivability rate and the number of shoots per explant than segmented pseudobulbs. However, if accumulated, segmented pseudobulbs can produce the number of shoots 2-4 times more than unsegmented pseudobulbs. The segment that had the highest average number of shoots was the basal segment. Two types of shoots were observed, both single shoot and multi shoot.  The new shoots formation was developed from protuberance and or axillary bud. Roots were kept to grow only on the basal part of unsegmented explants and basal segment.