Induced xenogamy enhances capsule formation, seed viability, in vitro seed germination, and seedling growth in the threatened orchid Diplomeris hirsuta: A strategy for conservation

Diplomeris hirsuta, a medicinally important yet threatened terrestrial orchid species, is vulnerable to extinction as per the IUCN Red List. This study aimed to investigate the influence of different pollination methods on D. hirsuta seed viability, seed germination in tissue culture media and their subsequent plant growth. A field experiment (on pollination systems) conducted in North Sikkim, Phamtam, revealed significant positive effects of different pollination treatments on capsule formation, with induced xenogamy demonstrating superior results. Cross-pollination techniques, particularly induced xenogamy, increased the percentage of capsule formation by 190% and enhanced capsule dimensions compared to natural pollination methods. Induced xenogamy resulted in seeds with higher viability (85.7% higher) and germination rates (737% higher), contributing to the better vigour and growth of D. hirsuta offspring compared to the control treatment, with the most promising results in BM-1 terrestrial media. Tissue culture experiments with BM-1 terrestrial media demonstrated the most successful seed germination and subsequent seedling growth. Thus, induced xenogamy treatment can be recommended for improving capsule formation, seed viability, and seed germination of D. hirsuta orchids. Additionally, BM-1 terrestrial media can be used for the successful mass multiplication of these orchids.