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lighter veins

Posted by lathyrus_odoratus 5A-IL (My Page) on
Tue, Oct 19, 10 at 3:51

Sometimes my Saintpaulia have light veins in a darker leaf. I am guessing that this is not normal, though I do see a fair amount of pictures showing plants grown this way.

Most recently this problem started to clear up when I lowered my soil solution pH to the 5.8 to 6.3 range. I'd inadvertently created a batch of soil that had too much lime. I am also guessing that this was caused by a deficiency of N, but that's just a guess.

I'd like to find out what the possible causes are and if it's something that can and should be fixed. For example is it always an N issue but different things cause the deficiency in N, or can it be different nutrients that are in short supply?

I'm posting a picture of a Saintaulia with these characteristics. It's not my plant, but interestingly enough, a person on another forum posed a similar question about her plant earlier tonight.

Here is a link that might be useful: Picture of lighter veins, darker leaves


Follow-Up Postings:

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RE: lighter veins

I am seeing this on some of my AV's too. I had thought it was because of what hybrid they are. I never thought that the veins showing could be a growing problem. Hopefully someone will answer that may know which it is. I had thought it looked pretty too!


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RE: lighter veins

  • Posted by tapla z5b-6a MI (My Page) on
    Tue, Oct 19, 10 at 8:47

What are you using for fertilizer?

Al


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RE: lighter veins

Hi Al, I'm using DG Foliage Pro.

I do not know what the other person - whose picture I posted - is using.

I wish I'd taken photos of mine 3 months ago when the problem was most pronounced. I can still see it in some - the leaves continue to get darker and glossier over time.

Frazzledgessie - I initially thought what you did. Then, when I realized my pH was too high (I started having other issues) and I lowered it with some vinegar in my water, I noticed that the veins started to darken. In some, it went away. That led me to wonder if it was supposed to be there or not!

I searched for quite a bit about veins and nutrient issues, but mostly can find only interveinal chlorosis. I did see one reference to sulfur deficiency as causing lighter veins than leaves, but many references about sulfur deficiency didn't mention this. DG's site says that FP has .05% sulfer. A document I found from Univ. of Florida suggested the moderate range of sulfur is .3 to .8 in Saintpaulia leaves.

Here is a link that might be useful: Saintpaulia percent nutrients in leaves


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RE: lighter veins

I use the same fertilizer that you do. There was only a brief couple of waterings this year that I used MSU on the violets. How do you test the pH of the soil?


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RE: lighter veins

  • Posted by tapla z5b-6a MI (My Page) on
    Wed, Oct 20, 10 at 17:04

I won't pretend that I know, but leaf color is a funny business. There are nutritional issues, mostly with micronutrients that can make the interveinal areas of leaves exceptionally dark, which makes the lighter veins more pronounced.

There are elements OTHER than nutrients that also affect pigmentation, and tiny variations of cellular pH can have considerable affect on the color of blooms and foliage.

You may glean something from this. It's something I wrote about pennies not changing the bloom color of hydrangea, and how that whole pigmentation thing works:

Pennies are made of zinc, aluminum ions are what affect the color of hydrangea blooms. Actually it is plant cellular pH that determines bloom color, not soil pH. Lowering soil pH makes aluminum ions readily available for plant uptake where it bonds to pigments in the blooms. Here is a post I left on the Botany Forum awhile back. It might be a little technical for new gardeners on this forum, but the general concept is easily understood:

"Three different pigments - chlorophyll, flavonoids, and carotenoids - mixed in different proportions, give color to plants. By mixing and matching the three pigments, an endless variety of colors can be created. E.g. most reds are the result of mixing orange carotenoids with magenta flavonoids. Cellular pH (not to be confused with soil pH) has a profound effect on plant color.

Even most experienced gardeners think that lowering soil pH produces blue blooms in hydrangea. Technically, it is only a part of the equation. Lowering soil pH makes aluminum ions more readily available for plant uptake. The aluminum is then available to bond with pigment compounds (anthocyanin, the colored component of flavonoids) changing the way color is reflected. Our perception is blooms changing from pink to blue.

The anthocyanidin group is what makes apples, autumn leaves, roses, strawberries, and cranberries red. They make blueberries, cornflowers, and violets blue. They also make some grapes, blackberries, and red cabbage purple. One of the things that changes the color of anthocyanins is the level of acid or alkali (the pH) in the cell surrounding the pigment. As cellular pH increases, the pigment changes structure and reflects different wavelengths of light. The anthocyanin reflects bright pink in acid cell environments, reddish-purple in neutral and green in more alkaline cells.

Since actual elemental availability and possible nutrient "lock-up" or overload due to soil pH can also have an impact on cellular pH, it's a good bet that having your soil professionally tested for pH and to see what nutrient problems there might be would be a good first step to definitively identifying the cause of the changes you observe." (skip the soil test part)

*****

It doesn't have to be one of the essential nutrients (if it is indeed a chemical issue), either in short supply or excess, causing what you described.

Like I said - not pretending that I have the answer to this - just throwing stuff at the wall to see what might stick - hoping you might see something that makes sense.

Al


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RE: lighter veins

Thanks, Al. Will ponder it for awhile and see if anything makes sense...

Frazzled, I have a pH meter that I bought for canning food. I take 1 part soil mix and 1 part water (with fertilizer and any other additives in it) and let them soak 5 minutes. I remove the soil mix and test the pH of the water.

Per the AVs, I've seen pictures of the same cultivar and the leaf color can vary tremendously, from light green to dark. In the same cultivar, sometimes the veins are same color as the leaves, sometimes not. There must be something going on that doesn't dramatically affect plant growth and performance, but that does show up in this way. Maybe I'll write AVSA and see if anyone has done any research about it.


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RE: lighter veins

I've received a response from some Gesneriad experts, but have been so busy I haven't gone through them all. I will post here when I can put all the info together. In the bit I did read, I found it interesting that in Saintpaulia sometimes the leaves and veins have different pigments. More to come.


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