Monday, 1 October 2012

Testing Phototropism

Another long day and so to relax I will blog.

Or try to! Keep getting distracted by March of the Penguins. Right game face on, last week I set up an experiment to show my year 9's the effect of phototropism. I will probably show them the photos in tomorrows lesson.

So hello 9Y1!

OK in order to do this experiment you need some seeds- in this example cress that I had grown in an experiment to show hydroponics to my year 10 class.

Hello 10C!

Here is the propagator.

And a close up of the cress in the propagator;

The next job was to take the cress out of one of the wells and place it in a small pot.

A modified plant pot with a hole in the side and the top sealed off. This allows light into the pot by one entrance only. Remember what should happen is that the auxin in the stem causes the shoots to move towards the direction which light is coming from. A time lapse video I took of this movement in some other seedlings can be found here.

The final experimental set up.

And the set up in situ in our greenhouse.

The experiment next to some pepper seedlings we are growing.

After 4 days the cress has clearly started to move towards the light.

And a close up of the cress showing positive phototropism. You can also just make out some slightly yellow leaves on the smaller shoots that haven't been able to get sufficient light during the experiment.

And a slightly different angle showing inside the pot and the yellower leaves more clearly.

And there you have it, a simple experiment to show phototropism. If you set this up on a Friday you should be able to see the effect on the Monday following. I will try and set up an experiment to show the effect of auxin on the stems if the shoot tip is covered etc - like you see in textbooks. 

So wish me look with that one!

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