Seed viability testing for research and conservation of epiphytic and terrestrial orchids

Abstract

Background Seed viability testing is essential in plant conservation and research. Seed viability testing determines the success of ex-situ conservation efforts, such as seed banking but commonly testing protocols of orchids lack consistency and accuracy, therefore, there is a need to select an appropriate and reliable viability test, especially when conducting comparative studies. Here, we evaluated the suitability of three seed viability tests, Evans blue test (EB), Fluorescein diacetate test (FDA) and Tetrazolium test (TTC), with and without sterilization, on seeds of 20 orchid species, which included five epiphytes and fifteen terrestrials, using both fresh seeds and seeds stored at − 18 ºC for 6 to 8 years. Results We found that sterilization and lifeform of seeds affected seed viability across all tests but the storage time was not an influential factor. Sterilization negatively affected seed viability under EB and FDA test conditions but increased the detection of viable seeds in the TTC test in both epiphytic and terrestrial species. The EB test, when administered without sterilization provided the highest viability results. Being non-enzymatic unlike TTC and FDA tests, as expected, the EB test was the most reliable with similar results between sterilized and not sterilized seeds for most epiphytic and terrestrial species as well as when compared between groups. Conclusions The lifeform of the species and seed sterilization prior to testing are important influential factors in orchid seed viability testing. Since EB test was found to be reliable we recommend the EB test for seed viability assessment in orchids rather than the less reliable but commonly used TTC test, or the FDA test, which require more expensive and sophisticated instrumentation. Since storage time was not an influential factor in orchid seed viability testing, the recommendations of this study can be used for both fresh as well as long-term stored orchid seeds. This is helpful for research and especially for conservation measures such as seed banking. However, due to the species specificity of the bio-physiology of orchids, we call for comprehensive viability test assessment in the hyper diverse orchid family to be extended to a greater number of species to facilitate efficient conservation and research.

Nano-silver and forskolin regulate rice seed germination mediated byOsPIP2-1

“…TTC (2,3,5-tryphenyl tetrazolium chloride) staining and Evans blue staining were used to judge seed viability. TTC dyes viable tissues red, whereas Evans blue dyes non-viable seeds blue (Pradhan et al, 2022). As shown in Figure 1h, compared with the control, AgNPs and forskolin had almost no effect on embryo color, indicating that any regulation of germination by AgNPs or forskolin did not affect embryo viability.…”

The challenges of growing orchids from seeds for conservation: An assessment of asymbiotic techniques

“…Thus, when starting research on a new species, we suggest that incorporating seeds of varying age is ideal to explore how different pre‐treatments, media, and growth conditions may influence germination as well as protocorm and seedling development. Testing viability across seeds (Pradhan et al, 2022 ) of varying ages may be a cost‐effective means of identifying the optimal age of seeds for each developmental stage from germination to protocorms to photosynthetic plants (Hosomi et al, 2012 ; Seaton et al, 2018 ).…”

Correction to: Seed viability testing for research and conservation of epiphytic and terrestrial orchids

“…In the publication of this article (Pradhan et al 2022 ), there was an error in the current (3rd) affiliation for Francesco Martini. The error: “ 7 Present Address: Center for Interdisciplinary Research On Ecology and Sustainability, National Dong Hwa University, Hualien 97401, Hualien, Taiwan.” Instead his address is: “ 7 Present Address: Faculty of Forest and Wood Sciences, Department of Forest Ecology, Czech University of Life Sciences Prague, Prague, Czech Republic.”…”