Exploring the Effects of KCl & NaCl on Stomatal Opening

In summary: So it's possible that there's simply more of it around, and as a result, more channels to move it into the cell. I don't actually know the answer to that. But potassium is, as you see, a signalling substance. (both in plant and animal cells), so its presence is fairly tightly and actively regulated. So it's possible that there's simply more of it around, and as a result, more channels to move it into the cell.
  • #1
rowkem
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0

Homework Statement



So we did an experiment where we put a leaf section in KCl and another leaf section in NaCl. There was a marked difference in the percent of stomata that opening between the two. We let the two sections sit in solution for 60 mins each.

The leaves in KCl had almost twice as many stoma open as the leaves in NaCl. Both were the same pH and had equal light exposure. The measurement areas were of roughly equal size.

That said, the key difference was the presence of K+ ions as opposed to Na+ ions. Now - I can't figure out why the two ions would produce such different results. Any ideas?

The Attempt at a Solution



I think it has something to do with on being positive and the other ion being negative. Though, I can't explain it in terms of the osmotic potential between the extracellular and intracellular regions, which cause the water to flow to regulate the guard cells of the stoma. Does K+ create higher osmotic potential which then means more water movies into the guard cells - thereby increasing the stomatal opening and therefore CO2 uptake, which means a higher photosynthetic rate? Or have I got this completely wrong? I've looked for lit on this topic and it's very limited, if at all existent.
 
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  • #2


rowkem said:
I've looked for lit on this topic and it's very limited, if at all existent.

I assure you, there's plenty of literature on what potassium ions do to stomata.
 
  • #3


alxm said:
I assure you, there's plenty of literature on what potassium ions do to stomata.

Yes, I realize there is much literature on what potassium does, seeing as how that's what typically moves through the transport protein. There isn't lit though, on why sodium is less effective is opening stomata.

Could it be that plants have simply evolved to use potassium, and therefore there's more transport proteins? Could it then be said that plants haven't evolved to use sodium and therefore there aren't as many transport proteins to pump the sodium into the intracellular region?

Are transport proteins that selective in the ions they move?
 
  • #4


rowkem said:
Are transport proteins that selective in the ions they move?

Yes they are. K+ channels have a set of four box-shaped 'cages' stacked on top of each other, where the corner of each 'cage' is an keto-oxygen from the protein backbone. The geometry is so precise that only potassium will coordinate to all six corners, and ultimately pass through.
2zi4f8g.png


MacKinnon got the 2003 Nobel prize in Chemistry for figuring out how it worked.
 
  • #5


alxm said:
Yes they are.

OK - that has help immensely. I realize now that sodium channels are highly selective and I did a quick read up on the topic. Thanks.

So - last question. Have plants evolved to have more potassium ion channels than sodium channels? If this is the case, then we can make some conclusions.
 
  • #6


rowkem said:
So - last question. Have plants evolved to have more potassium ion channels than sodium channels? If this is the case, then we can make some conclusions.

I don't actually know the answer to that. But potassium is, as you see, a signalling substance. (both in plant and animal cells), so its presence is fairly tightly and actively regulated.
 

1. What is the purpose of this experiment?

The purpose of this experiment is to study the effects of different concentrations of KCl and NaCl on stomatal opening. Stomata are small pores on the surface of plant leaves that control gas exchange and water loss. By testing the effects of these two salts on stomatal opening, we can better understand how they affect plant physiology and potentially inform agricultural practices.

2. How will the experiment be conducted?

The experiment will be conducted by preparing solutions of varying concentrations of KCl and NaCl, and then applying them to plant leaves using a sprayer. The stomatal opening will be measured using a microscope and a specialized leaf chamber. The experiment will be repeated multiple times to ensure accuracy and validity of the results.

3. What are the expected results?

Based on previous studies, it is expected that higher concentrations of KCl and NaCl will result in decreased stomatal opening, as these salts can cause water stress in plants. However, the exact results may vary depending on the species of plant and the specific concentrations used.

4. How will the data be analyzed?

The data collected from the experiment will be analyzed using statistical methods to determine if there are significant differences in stomatal opening between the different concentrations of KCl and NaCl. Graphs and charts may also be used to visually represent the data and make comparisons between the groups.

5. What are the potential implications of this research?

This research can provide valuable insights into the effects of KCl and NaCl on plant physiology, specifically on stomatal opening. This information can be used in agricultural practices to optimize plant growth and productivity, as well as in understanding the impact of salt stress on plants in natural environments.

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