Seed dormancy is a common evolutionary adaptation in temperate plant taxa. Dormancy mechanisms can prevent seeds from germinating at inopportune times, such as a cold period. We report the influence of pregermination stratification treatments on in vitro seed germination and seedling development in Platanthera chapmanii, a rare temperate terrestrial orchid native to the southeastern USA. Seeds were subjected to 0, 8, or 12 wk of cold-moist stratification at 5°C; mean seed viability was 89%. At 9 mo after plating, seeds exposed to 8 and 12 wk of stratification resulted in higher germination (Stage 1; 32% and 35%, respectively) in comparison to 25% germination in nonstratified seeds. Once a protocorm developed a leaf primordium (i.e., reached Stage 2), development to Stage 3 (root development) was independent of the pregermination treatments. Exposure to artificial lights for 3, 4, and 5 mo resulted in 32%, 44%, and 63% of the Stage 2 seedlings, respectively, developing into Stage 3 photosynthetic root-bearing seedlings. Our results indicate that in vitro seed germination in this temperate terrestrial orchid can be improved by using cold stratification. Furthermore, leaf- and root-bearing seedlings can be obtained through the methods reported herein.
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1 December 2016
Cold-Moist Stratification Improves Germination in a Temperate Terrestrial Orchid
Kirsten E. Poff,
Jyotsna Sharma,
Matt Richards
Castanea
Vol. 81 • No. 4
December 2016
Vol. 81 • No. 4
December 2016
Asymbiotic germination
cold-moist stratification
ORCHIDACEAE
plant conservation
seed dormancy
sterile culture