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Onion Growth
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Posted by jimster z7a MA (My Page) on Wed, May 4, 05 at 17:21
| After trimming the tops of my onion seedlings several times, it occured to me that they must be growing from the bottom, not the top. I had not observed this before. Many plants, such as tomato seedlings grow from the top.
I decided to get more proof of what I seemed to be observing so, about a week ago, I marked three onion leaves 2" above the pot rim with a sharpie pen. Here is how they look today.
Jim
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Follow-Up Postings:
RE: Onion Growth
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Good observation.
The entire onion leaf is growing. To see this mark a leaf in 1/4 inch increments and see what happens.
Let us know! |
RE: Onion Growth
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| How is this onion growing experiment going? Tracy |
RE: Onion Growth
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| Tracy, My experiment was considered done when I saw (as shown in the picture) that the leaves had grown by 1/8", 1/4" and 7/16" as measured from a starting point 2" from the bottom. I interpreted this as growth added at the bottom of the plant, not at the top. Byrdzeye suggested that the growth may be occuring along the entire length of the leaf. I started the experiment he (or she) suggested and will give you the results soon. What do you predict? Is the growth of an onion leaf entirely from the base or all along the length of the leaf? We already know it is not from the top. I hope Byrdzeye will make a prediction. :-) Jim |
RE: Onion Growth
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I don't know for sure but my guess is all along the length of the leaf. My guess is based on how almost all leaves grow. The number of cells that make up the leaf are generally fixed when very small and all the cells increase in size as the leaf matures.
Can't wait to see what you come up with. |
RE: Onion Growth
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| That is good reasoning, byrdzeye. I won't make a prediction myself because I have the unfair advantage of seeing the plants daily. Measurements haven't been made yet, but will soon. Jim |
RE: Onion Growth
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| By any chance, did you measure the total length of the leaf? |
RE: Onion Growth
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| "By any chance, did you measure the total length of the leaf?" No. But that's a good idea. It would have been useful. I would then compare the change in total length with the change of the marked intervals. As it was, and as you can see from the picture, my markings and measurements were not precise enough to give a definitive answer. I can tell you that the tallest marked leaf, the one which leans farthest to the left, grew substantially during this experiment. The markings are at 1/2" intervals. When this picture was made, there was noticable variation from the original 1/2". But it didn't seem that all of them had increased. Most stayed about the same. My conclusion is that this experiment needs to be repeated with more precision. Jim 
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