What have you started here, Lesley...
I've had a rummage through my collected seeds and have found a few candidates for a germination experiment -
comments for the improvement of the experimental design are welcomed.
These are not what you'd call recalcitrant seeds, being those that I have in sufficient quantity and aren't too special to have a play around with. However, they should serve for a rough'n'ready experiment, and given the claims for the effectiveness of the "cup of tea" method we might see some difference in germination (and subsequent growth/flowering?) even in these species. The seeds have all been collected by me this year, except for 6. which is from the SeedEx and so a 2013 collection:
1.
Muscari armenaicum2.
Muscari - un-named cv., pale blue
3.
Narcissus pseudonarcissus - un-named cv., big trumpet
4.
Scilla siberica5.
Scilla verna - wild-collected ex Berneray
6.
Scilla verna - wild collected ex Orkney
I will test the following five treatments:
A. soaking as per Lesley's instructions using green tea
B. soaking as per Lesley's instructions using black tea
C. soaking as per Lesley's instructions using water
D. soaking for 24 hours only using water
E. no soaking
I've included treatments D and E as they will help to quantify the magnitude of any effect of the "cup of tea" method. Applied to each of the seed collections the five treatments will give 30 experimental pots in total.
We might expect to see a range of germination rates ranging from the highest/fastest (treatment A) through to the lowest/slowest (treatment E). So, the null hypothesis is that: soaking seeds prior to sowing has no effect on germination rates (speed and %age) and our alternative hypotheses are that:
- Soaking seeds in water results in faster/higher germination rates
- Longer soaking of seeds (>24 hours) results in faster/higher germination rates
- Soaking seeds in black tea as per Lesley's instructions results in faster/higher germination rates than using only water
- Soaking seeds in green tea as per Lesley's instructions results in faster/higher germination rates than using black tea
Other variables will be kept the same as far as is possible:
- seeds have all been exposed to the same storage conditions;
- 15 seeds will be sown for each treatment;
- seeds will be soaked in equal volumes of liquid from the same source/brew
- they will be soaked/sown on the same dates;
- the same size pots will be used (7x7x8cm);
- and the same medium (my usual gritty, loam-based bulb mix and top-dressed with grit);
- sown pots will be kept in the same location (in a frame covered with shade netting to keep the harshest winds off, but otherwise exposed to the elements);
- subject to the same watering regime; and
- anything else done to one pot, will be done to them all.
I will make regular* observations of the pots to record whether there are any signs of germination (cotyledons breaking the surface of the sowing medium) and if so how many seedlings there are. The results will be recorded in a table for later analysis. I'll let the experiment run until all germinated seedlings have gone dormant next summer.
*I'm unsure what the frequency of observation should be. Lesley's experiences with her Irises suggests rapid results, which would require daily observation. But I suspect that the seeds I'm using, that require a period of cold to germinate, may not react so quickly so less frequent (weekly?) observations might be adequate. However, there's rarely a day that goes by that I'm not checking on my pots, so I'll start with daily observations and see how it goes.
As regards observations of growth (leaf height? leaf number?) and time to first flowering... let's see how things go. It might be better to focus on germination rates at this stage, but making observations of growth probably would not be onerous (i.e. monthly).
Assumptions (can't be verified/measured with the means available):
- any effect of the "cup of tea" method is due to the presence of giberellins (rather than any other factor)
- unfermented green tea contains higher levels of giberellins than fermented black tea
Limitations:
- I don't have access to the Iris seeds for which Lesley reported an anectodal effect (not meaning to disparage your observations Lesley, just being scientifically rigorous)
- the use of cold germinating species may hide/diminish any effect of the "cup of tea" method
- holidays in Sept (timed with the Late Bulb Display)
and at Christmas will mean there are gaps in the data set.