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I want to know the physiological reasons of why the leaves of my study plant got twisted when treated for 10 days with spray of indole acetic acid. I want to treat seeds with IAA, and I'm thinking about testing what will happen when I treat the leaves.

Here is a picture of what the plant looks like:

twisted leaves


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Please add some images - ideally both treated and untreated leaves. – Chris Jan 22 '14 at 19:08
Add study species as well. Also give some background; why did you perform the experiment in the first place? Why indole acetic acid? – fileunderwater Jan 22 '14 at 19:25
IAA induces growth. perhaps that is leading to twisting. But unless you upload a picture and provide more information about the methodology it will be difficult for people to answer this question – WYSIWYG Jan 23 '14 at 4:59
@legend I think you need 10 reputation before you can add images yourself. I've added the picture now. – fileunderwater Jan 23 '14 at 9:59
Speculation on my part: since IAA can induce growth, spraying it mostly on one side of the leaf (by spraying from the top) might cause the upper part to growth faster, which would lead to the leaf twisting downwards. From the picture, this seems to be what is happening most of the time. +1 – fileunderwater Jan 23 '14 at 10:06

Disclaimer: Not my area of research

Since IAA (auxins) can induce growth, partially acting through cell elongation (, it seems likely that the explanation to your result is differential growth/elongation rates on the upper and lower side of the leaves. This could result from uneven spraying, e.g. by spraying the leaves from the top. Faster growth on the top part of the leaf would lead to downward twisting, which seems to be what is happening most of the time.

You could test if this is the case by doing a simple experiment where you carefully apply IAA with a brush on both sides of the leaves for some plants, while others are sprayed. If uneven application is the cause you should see twisting when spraying but not when applying with a brush.

However, auxin is toxic to plants at high concentrations, so you also need to consider the concentration you are using.

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The concentration was 50 ppm. – legend Jan 23 '14 at 10:34
@legend I have no idea if that is considered high or low. – fileunderwater Jan 23 '14 at 10:38

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