Pollen germination, What's it worth?

by Chris Thomas

So, after reading John Garrett's excellent article, frantically raiding your larder for onions or leeks (good lateral thinking there John!) and decapitating all flowering plants in your garden you've set up your little germination experiment and are waiting for it to work! What do you do now? Well, you could consider adding any information you gain to the fount of human knowledge. I would be very interested in hearing from you about your results and if we get enough of a response, we could try publishing it.

It will take a little more care on your part. Try to provide the following information:

1. Where geographically you obtained the pollen (flower). Latitude & Longitude if possible.
2. Date you conducted experiment.
3. Local time of day of experiment (24 hour clock or state am or pm.).
3. Name of flower from which you took pollen - Latin name and common name if possible.
4. Any additional points you thought of interest.
5. Pollen germination scores for three separate experiments determined as below.

Scoring pollen germination.

Apply pollen to the surface of onion epidermis as described by John Garret within 1 hour of picking flower. It is important that the pollen is streaked on the epidermis surface that has been in contact with the flesh of the onion - see John's picture! Place in humid sealed container. Score for germination 3 hours after applying the pollen to the epidermis and transferring to a humid environment in the sealed box. View using a x10 objective (circa 100 x magnification). Pollen grains are considered germinated if the length of the pollen tube exceeds one pollen grain width. Germination is scored visually by scanning the sample and assigning to one of seven score classes as follows:

1. no germination
2. 1% to 2% germination
3. 3% to 10% germination
4. 11% to 25% germination
5. 26% to 50% germination
6. 50% to 90% germination
7. 91% to 100% germination

The latter method is fast, reliable and better suited than direct counting to experiments where a number of samples have to be scored at the same time or where samples are likely to dry out under prolonged observation.

Once you find a species that gives very good germination, always include a test slide with that species with any new species your testing. That way you can be sure that any results you see are real.

For photography or observation of pollen tube germination on surfaces, the slide can be covered with a coverslip to prevent drying out on the microscope stage. The light source to the microscope has to be reduced with neutral grey filters (or use a cold light source such as a white LED - JG) to prevent heating of the sample that could cause the accumulation of condensation on the coverslip.

Please send your results to me by mail, I really look forward to hearing from you!

Chris Thomas
7 The Oaks
United Kingdom

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