Journal of Taiwan Agricultural Research

Author:Chin-Yi Tsao, Uei-Chern Chen, Tzu-Ying Wu, and Chi-Ni Hsia*

Abstract:

    This study was conducted to verify the effects of seed maturity, growth media composition and media sterilization on in vivo asymbiotic germination and seedlings growth of Bletilla formosana (Hayata) Schltr. Seeds collected from pods 60, 90, 120, 150 and 165 d after pollination (DAP) were sown on autoclaved or non-autoclaved media, including sphagnum moss (medium 1), peat moss (medium 2), carbonized rice husk (medium 3), and mixed media of sand : loam : carbonized rice husk : perlite = 1 : 1 : 1 : 1 (v/v) (medium 4) and sand : carbonized rice husk : perlite : vermiculite = 1 : 1 : 1 : 1 (v/v) (medium 5). Results showed that seeds of B. formosana were able to germinate and to grow normally on various autoclaved media. Growth media composition, seed maturity and their interactions were found to have statistically significant effect on days needed for germination. However, a less significant effect was found between autoclaved media and seed matured after 120 DAP. In this study, immature 60 DAP seeds were capable to germinate, and the shortest time for germination was observed in 165 DAP seeds. Factors of growth media, autoclave and seed maturity as well as their interactions showed significant effects (P < 0.01) on seed germination. It was observed that seeds of 90 DAP had germination rates higher than 80% in the appropriate growth media, and the highest germination rate was found on the autoclaved peat moss (84.1%), followed by the autoclaved medium 4 (81.1%), and the autoclaved medium 5 (72.6%). Although survival rates of seedlings derived from different maturity of seeds sown in various media with or without an autoclave with no consistency, it was found that seeds of 120 DAP sown in appropriate growth media had survival rates higher than 70%. An separated experiment using seeds of 120 DAP was conducted by sowing seeds in various autoclaved or non-autoclaved growth media for evaluation of seedlings growth. Results showed that factor of an autoclave work and types of media as well as their interactions all had statistically significant effects at 0.01 level. It was found that autoclaved peat moss showed the best result on the growth of seedlings. In average, 3.5 leaves and 7.0 mm in leaf span were found per plant. The results confirmed that B. formosana had autotrophic feature during seed germination and seedling growth when mature seeds were germinated on appropriate growth medium. It was observed that embryos of seeds were enlarged and turned into green in 10 d after sowing, and the first leaf appeared in 17 d after sowing from protocorms, and a complete plant with roots was obtained in 120 d after sowing. Growth media and maturity of seeds and their interactions were all found had significant effects on days needed for germination. However, a less significant effect by an autoclave was found from the more mature seeds (≥ 120 d). Factors of growth media, autoclaving and seed maturity as well as their interactions showed significant effects (P < 0.01) on seed germination and survival of seeding.

Key words:Orchid seed, Asymbiotic germination, Orchid mycorrhiza

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