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Wednesday, 4 April 2012

Watching seeds germinate

 Many seeds will germinate happily on moist cotton wool or a damp face tissue. Wheat, tomato and radish are good ones to try. As they grow, they can be observed under the low or high power of a binocular microscope.

The tissue stays damp longer in a Petri dish, so I have described using that, but you can always adapt the details, and sometimes I use a plastic berry box.

Fold a tissue in four, mark a circle with a pen and the base of the dish, then cut just inside the circle with scissors and put the tissue in the dish, add some water and seeds, and put the lid on. Then wait and watch.

Dandelions also work, as you can see from the shot above and the two on either side.

Seeds will also germinate in water agar in a Petri dish: add 1.5 grams of agar-agar powder to 100 mL of water, boil it, and pour a layer about 6 mm deep into as many dishes as you can fill (you can always scale up the amounts, but the aim is always to have a 1.5% powder to water ratio).

Radish seeds can be pressed into the jelly, and if you seal the dish with tape (so it won't dry out) and stand it on edge, you can rotate the dish 90 degrees every few days, and see how the root always grows downwards.

Other seeds to use: most weeds including cobbler's pegs. Bidens sp., (weeds have to be good at germinating fast!), wheat, or make your own choice from the garden.

Bird seed from a pet shop (NO, bird seed DOES NOT produce birds!) is sometimes treated with radiation to stop the seeds sprouting, but you could also try that.

Because I was writing about these seedlings, I kept them on the window-sill in my study.  This has a north-facing (i.e., sunwards in Australia) aspect, and naturally, the seedlings grew towards the light.

Then I put a handy quartz pebble (in my house, there are always pebbles to be had) in the tub, to mark what had originally been the sunward side, and then I turned the tub around.

This took a couple of days to take effect, but you can see the result in the third shot, and now you can see why I needed the pebble in there as a marker.

While testing methods for the book, I tried using scented face tissues to germinate one batch of cobbler's peg seeds and I found that the seeds took longer on "eucalyptus and aloe" tissues than they did on paper towelling.

This is easy to explain if you know that eucalyptus oil can stop seeds germinating.

To test this, put some seeds on a wet wad of tissue in a saucer and add a second small container with a tissue and a few drops of eucalyptus oil. Set the saucer and the container in a plastic bag and seal it with a fair amount of air inside.

Suitable seeds to use for this include cucumber, radish, lettuce and white mustard. If they are commercial seeds sold for planting, they have may been treated with pesticides, so don't chew them. Take care not to get eucalyptus oil in your eyes, as it is quite painful. Use goggles to be on the safe side!

Then we took the plants section out, so here it is in the blog: over to you!

A few seeds are fussy and difficult. For example, some Australian bush plants only germinates after a fire, and it appears that the trigger is chemicals found in smoke, rather than the heat of the fire—or that was the official line last time somebody quoted it to me—this makes them sprout after a fire.  There could be a nice project hiding in there!

She-oaks (Allocasuarina), Banksia and Hakea are among the species that drop seeds from woody fruits, almost as soon as the fire has died out.  Some of the banksias and other plants have underground stems which are protected from the heat of the fire, and these send shoots up after a fire.  Gum trees survive by sending out new shoots from living tissue, deep beneath the bark.

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This blog covers quite a few different things, so I tag each post. I also blog about history, and I am currently writing a series of books called Not your usual... and the first two have been accepted by Five Mile Press, The offcuts appear here with the tag Not Your Usual... . For a taste of Australian tall tales, try the tags Speewah or Crooked Mick.   For a miscellany of oddities, try the tag temporary obsessions. And language us covered under the tags Descants and Curiosities, while stuff about small life is under Wee beasties.

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