germination test

Ashley Clayton and Peter Zale, Longwood Gardens

At the Valmont Bog in Hazelton, PA, there are populations of three, state-listed taxa of Platanthera: P. ciliaris, P. blephariglottis, and P. xbicolor, a natural hybrid of the other two species. They are threatened by forest succession, climate change, silt-laden runoff, and herbicide spraying. However, as is the case for most native orchids, conservation efforts are hindered by limited propagation information. To support in situ and ex situ conservation of these species, this experiment was designed to determine the most effective mycorrhizal fungi for in vitro germination of each taxon. In August 2018, pelotons were isolated from the roots of each species and maintained in culture. Multiple capsules from each orchid species were then collected the following month. Seeds were surface sterilized in a 10% bleach solution for 18 minutes and rinsed with distilled water. They were plated on an agar-based medium containing powdered Liriodendron tulipifera wood and inoculated with one of the three fungal isolates. Visual inspection showed that at least 71% of seeds on each plate contained healthy embryos except for seeds originating from one capsule of P. xbicolor, which only about a third had embryos. Visual observation also revealed an association between the hyphae and the rhizoids of protocorms. The peak germination occurred between four and five weeks after sowing. After seven weeks, seed germination ranged from 0 to 27%. Compared to a previous preliminary experiment, the addition of mycorrhizae decreased the time of peak germination from several months to about one month. The effect of each mycorrhiza on germination percentage and protocorm development is still being determined.

Contributing Author(s): 
Date Recorded: 
Friday, May 3, 2019

Philip Gonsiska,Bok Tower Gardens

Ziziphus celata is an endangered shrub endemic to Polk and Highlands Counties in central Florida. Germination in this species has generally been very low, and previous observations have suggested that upwards of 75% of seeds set by Z. celata may not be viable. In January 2019, cutting tests were conducted to estimate the viability of Z. celata seeds harvested in summer 2018. Dissected seeds were categorized as “normal”, empty, moldy, “spongy”, and those having shrunken embryos. Those in the “normal” category were thought to be viable. Of the 103 seeds dissected, 36 (34.95%) appeared “normal”, 35 (33.98%) were empty, 24 (23.3%) were moldy, six (5.83%) had shrunken embryos, and two (1.94%) were “spongy”. In earlier work, soaking seeds in a 0.1% liquid smoke solution resulted in a germination rate of 26.7%, which thus far is the highest germination rate in our data set from any experimental seed treatment applied to Z. celata. Therefore, seeds from 2018 were soaked in either a 0.1% liquid smoke solution or reverse osmosis water for 24 or 48 hours. They were then sown in 72-cell trays along with unsoaked control seeds. These trays will be monitored for germination for six months, and the realized germination rate will be compared to the hypothetical percentage of viable seeds from the cutting tests. Preliminary results of this experiment will be presented.

Contributing Author(s): 
Date Recorded: 
Thursday, May 2, 2019

CPC 2019 National Meeting Videos now in PI Portal! See Cheryl's Germination Testing Video

Apologies for cross posting (this is why we need an announcements channel :)), but the CPC National Meeting Videos are ready for viewing in the PI Portal. They will be moved to plant nucleus in our next phase of development (coming soon!). Take a sneak peak at Cheryl's

Recommendations for incorporating phylogeny into a survival analysis of germination data?

According to the attached review of germination data analysis (McNair et al. 2012), time to event analysis (survival analysis) is the recommended approach for analyzing germination data. Does anyone know of a study that incorporates phylogeny as a covariate in a survival analysis?

Setting up germination tests

I'm new to germination testing and will be running germination trials on lots of different species (mostly midwest natives). What kind of plates/containers do you use? What kind of media- agar, blotter paper, sand?) do you use and what do I need to know about keeping it watered/sterilized/labeled? 

Do you always steralize your seeds before "planting" them? If so, what protocol do you follow?

Please share your trials and tribulations! Thanks!

What kind of germination/growth chamber do folks recommend for seed viability testing?

Our growth chamber broke recently and we're hoping to replace it with something cost-affordable, reliable and not too big for our relatively small space. It will sit in a room shared with seed processing equipment (and people), a biomass oven and is used with some frequency.

Does your institution have germination data of seeds stored after 1, 5 or 10 years?

CPC is interested in learning about general longevity of rare species after several years in storage.  If enough data exists, then we will be able to do a meta-analysis.



Ed Guerrant, Rae Selling Berry Seed Bank

Penstemon peckii (G3-S3 Federal SOC) is an Oregon endemic with a relatively compact range in the semi-arid Ponderosa pine forest east of the Cascade Mountains. The vast majority of known populations (ca 93%) are almost entirely within the Sisters Ranger District of the Deschutes National Forest. A 1992 Species Conservation Strategy by Cindi O’Neil found that it is “Best adapted to open full sun habitats, low vegetative competition and natural fire.” The natural fire frequency was 7 to 15 years, but active fire suppression for many decades had diminished and degraded habitat. Number one in the “What we do not know” list is “How long does Peck’s penstemon seed remain viable in the soil seed bank?” To address that question, in 1992 we gathered seeds from multiple populations across the species’ range. We mixed seeds from 11 populations into a single, large bulk sample in order to compare their survivorship in the soil seed bank and in an ex situ seed bank. In addition to initial trials of fresh and dried and frozen seeds, samples have been removed from the field and ex situ seed bank after 6, 12, 18 months, and then at 4, 15 and now 25 years. The current round of germination trials of 25-year old seeds is still underway, but to date, approximately 26% of those stored in the soil and 51% in the freezer have germinated. The species clearly has the capacity to form a long-lived soil seed bank.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018