Author Topic: sunburn from led lights?  (Read 1443 times)

incubator01

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sunburn from led lights?
« on: August 09, 2021, 05:04:19 PM »
I am trying to identify weather my 3 nagami kumquat seedlings are having sunburn from being 10 - 12h / day under a small LED growlight or if this is from something else.
They are not getting direct sunlight, however they are located near a window made of milk glass, so its completely blurred and milky white, the sunlight is heavily filtered.
The LED light I use is PARUS LED grow light SOL Series (PGL-E18) specs found in english here: http://parusplantlight.com/download/e18-specifications

I keep the plants definitely more than 20cm away from the light, when turning the light off at night I spray the plants with a foliar spray sometimes, rainwater other times to maintain moisture levels.
I water with rain water every 2 - 3 days a little bit because these things have tiny roots , the rain water is mixed with an auxine based root booster and once a week I add liquid fertilizer for citrus (planfor citrus , qualifies in most areas)
They're planted in seeding soil that drains very well and also dries out nicely inside.
However the first 3 weeks I had no sign of these burn marks, only since today did I notice it.
Thing is that this happens to every citrus seedling I tried so far, tomato or chili pepper seedlings do not have this problem.
Does anyone have a clue as to what is going on?
Attached are images of each plant.








CanadianCitrus

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Re: sunburn from led lights?
« Reply #1 on: August 10, 2021, 07:31:05 AM »
Itís only pumping 25 watts which is not very much right now. Iím using a 300 watt LED and I havenít had any problems yet. Could it be damage from soluble salts?

incubator01

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Re: sunburn from led lights?
« Reply #2 on: August 10, 2021, 08:05:44 AM »
Itís only pumping 25 watts which is not very much right now. Iím using a 300 watt LED and I havenít had any problems yet. Could it be damage from soluble salts?

Perhaps, I have no idea, that's why I put it up here, but maybe the nutrition I added has those.
Guess they're too young for that and I'll have to stick with root booster only then for now.

poncirsguy

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Re: sunburn from led lights?
« Reply #3 on: August 10, 2021, 12:51:34 PM »
Nagami and Meiwa kumquat seedlings are very difficult for the first 30cm of growth.  I gave mine 16 hours from a 23 watt daylight CFL set 4 inches from the top leaves inside a bright white chamber.  I lifted the plant so that a half inch of root was showing to protect it from damp-off disease.  I use Miracle Gro 24-8-16. with 6 plants in a 1/3 liter pot till they were 15cm-20cm tall.




incubator01

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Re: sunburn from led lights?
« Reply #4 on: August 10, 2021, 01:22:02 PM »
Nagami and Meiwa kumquat seedlings are very difficult for the first 30cm of growth.  I gave mine 16 hours from a 23 watt daylight CFL set 4 inches from the top leaves inside a bright white chamber.  I lifted the plant so that a half inch of root was showing to protect it from damp-off disease.  I use Miracle Gro 24-8-16. with 6 plants in a 1/3 liter pot till they were 15cm-20cm tall.




Wow, that's pretty strong nutrition, the liquid fertiliser (sunplant citrus) I use has an NPK 11-3-6 , the slow release I use has an NPK of 16-7-15,
My seedlings right now are about 3 weeks old, I read I should repot them once they have about 4 leaves but at what age did you lift this root?

poncirsguy

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Re: sunburn from led lights?
« Reply #5 on: August 10, 2021, 07:40:22 PM »
As soon as I had 3 inches of root.  Kumquats grow so slowly that it takes too long to get through the damp-off susceptible stages and are killed

incubator01

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Re: sunburn from led lights?
« Reply #6 on: August 11, 2021, 03:29:50 AM »
As soon as I had 3 inches of root.  Kumquats grow so slowly that it takes too long to get through the damp-off susceptible stages and are killed
ok, thanks, mine aren't that far yet, I'd say the roots are maybe almost 1 inch atm.

Ilya11

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Re: sunburn from led lights?
« Reply #7 on: August 11, 2021, 11:17:51 AM »
For me this is a damage due to  fertilizer excess.
Best regards,
                       Ilya

Millet

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Re: sunburn from led lights?
« Reply #8 on: August 11, 2021, 11:56:29 AM »
I totally agree with  Ilya11, it certainly looks like fertilizer soluble salt damage.

incubator01

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Re: sunburn from led lights?
« Reply #9 on: August 11, 2021, 12:47:37 PM »
Ok, thanks.
I'll stop giving it for a while then until they're showing signs of deficiency.

Millet

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Re: sunburn from led lights?
« Reply #10 on: September 21, 2021, 10:45:12 AM »
I seriously doubt the slight damage to incubator's tree leaves was caused by LED lighting.  I agree the leaves show soluble salts damage from the fertilizer over supply.

incubator01

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Re: sunburn from led lights?
« Reply #11 on: September 21, 2021, 02:15:21 PM »
I seriously doubt the slight damage to incubator's tree leaves was caused by LED lighting.  I agree the leaves show soluble salts damage from the fertilizer over supply.

And I too agree with your conclusion.
To try out I planted some kaffir lime seeds in the end of august, atm 2 seedlings are growing slowly but healthy and 2 are about to stick their heads out.
I did not feed them with anything at all yet, (so for one month now I watered with rain water without any kind of nutrients) and I used a soil of seeding soil mixed with some coco fiber.
They're doing very nice, good green leaves, tiny but healthy. and I put them under 14h of LED light, even placed a second one next to it to cover larger area, no problems at all.
With the kumquat seedlings and even with some adult citrus I admit I probably gave too much food and that caused this issue.

So I will wait with giving nutrients until they grow 3 pairs of true leaves and then I start with liquid fertilizer, but one that is on the weak side, because if I give a strong one right away I might kill them again.

 

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