Genetic expression or nutrient deficiency?

[seymore_budz]

Hey GR420,

I have a little issue I would like some advice with. I have started some mango sapphire from Humboldt Seed Organization. Everything was going great and they were growing fast and still are growing great but they seemed to have yellowed off a bit and have now turned purple on the underside of the leaves.

Room is sitting around 22C and about 50% humidity. Thats consistant throughout the day and night. They're in batmix that is about 10 days old. The batmix wasn't rinsed as adviced by Plagron but I'm not seeing any burning or signs of overfeeding.

This seemed to happen when I swapped over to the new T5HO lamps from my knackered CFL. I first thought it was stress due to the increase in light but I'm now thinking they could be humgry? The batmix was opened quite some time ago but I can't see that affecting the available food?

They're being watered with RO water with a bit of nitrozyme and some calmag to take the edge off the RO.

I've read this can also be a genetic thing? All three are doing the same thing and it's pretty consistent? Have I just got some cool looking plants or am I underfeedings? What do you think? I'm thinking P def with the slight purpling of the stems and the leaf discoloration but I don't want to correct a problem that doesn't exist. It seems a little early in the cycle to have such a dramatic P def in batmix? Could it actually be lightburn too? I'm bamboozled :)

Topside, as you can see, it's not yellow and actually looks healthy but almost lime green.



Underside of the leaf.

[Keeno]

Hey GG,

I've not used bat mix, RO etc so a bit out of comfort zone here. What I will say is I've not seen the like before, especially the pattern of the purps under the leaves. It is a lighter green but as you say dont look hungry. I'd be inclined to lean towards genetics and if it is it could be something real special to be colouring up so early. Treat her well mate, could be the next exo

[GMO]

from the way its clustered and not fully on any leaves it looks like it was a time period where they were struggling to deal with the about of light and werent able to produce proper green pigments

but again from where the colours are showing it looks like it was in the late stages of seed leaf growth and the start of the first node but seems to be subsiding now

id watch it for a few days and see if it spreads or just stays put

[seymore_budz]

Cheers Keeno and GMO,

I was leaning towards sunburn but wanted to get another opinion. I was toying with deficiencies etc but the light was always ringing in the back of my head. It's the only thing that has changed. Seems as I've underestimated the power of the sunblasters. I always thought you could get these low wattage t5s close because of how cool they run. I've got to admit, they look loads more powerful than the CFL and a completely different colour. Much more blue, do you think this is UV damage?

[Mafooo]

Hi guys. I think I might be able to chime in here

I will start off by saying she doesnt look unhealthy! I think she will be fine. Has she slowed growth at all though?

What spectrum t5 bulbs are u using, how many in the lamp fixture, and how close to the plant?

I am finding A LOT of interesting leaf color morphology expression in my plants grown under T5 and my LED panels. Seems that leaf color expression can be influenced by spectrum ratios and other environmental conditions like temp and light intensity

[Nanook]

I agree re light stress. I saw the same but worse on my 9 cdm grow.

[seymore_budz]

I agree re light stress. I saw the same but worse on my 9 cdm grow.

Yea man, got a bit excited I think Nanook and blasted them with too much :)

Hi guys. I think I might be able to chime in here

I will start off by saying she doesnt look unhealthy! I think she will be fine. Has she slowed growth at all though?

What spectrum t5 bulbs are u using, how many in the lamp fixture, and how close to the plant?

I am finding A LOT of interesting leaf color morphology expression in my plants grown under T5 and my LED panels. Seems that leaf color expression can be influenced by spectrum ratios and other environmental conditions like temp and light intensity

Hey Mafoo.Martin,

They haven't been slow if I'm honest, they still growing fast and reaching for the light. The bulbs are 6400K. They're sunblaster T5HO kits. I have 2x 24w kits. I first put them about 1.5inch above them as recommended but my old light was fucked and they were too young for all that light I think so they now about 3" above the canopy. I'll keep you all posted!

Here are all three today. They all look happy enough and reaching for the light and no necrosis yet thank god :) Fingers crossed I haven't burnt them lol.

[Mafooo]

Dude they look fine to me just keep em under ur watch. Keep taking cool pics of their colors!

[seymore_budz]

Hi GG,

I've had purpling on the undersides of certain strains too, I'm going to say it's genetics.

The T5 I keep about 6 inches away from the plants, they all lean into the centre of the tubes too you may start to notice.

I wouldn;t worry about burning them. I have had them grow into the tubes when forgotten about, you can literally put the light right on top of them when they're a bit bigger.

Plants look cool, a tad overwatered maybe? That could explain the lighter colour to them, roots not able to grow and uptake all that lovely bat poop!

I'm sure they'll grow into it.

Thanks Marcus,

I'm pretty sure it's light strees bud. Thanks for the tip on the T5s! I've used t5s before and had them pretty close without issues but never when the plants are this small. I think I just got way too excited. I used a lux meter to measure the old CFL and at the canopy it was outputting ~15k lux. Those two T5s were kicking out 50k lux at 1.5inch. I think 3-6" is more on the money when it comes to young plants. These are the high output T5s not sure if that makes any difference or not?

I'm on the watering pretty well bud. I've grown in batmix a few times now and I've got the watering pretty spot on I think. They look wet there because they have just been watered though. I don't really measure the amount of water they each get as it varies based on the environment but I stick my pinky in the tops of the pots and if the first inch is dry and they feeling light, they get water.

Hopefully they will come right again. They still growing but I suspect the necrosis will come in the next 48hours.

[seymore_budz]

Just an update, thanks all for your help. I'm pretty sure this was sunburn. I think I caught it just in time as they're looking better now and only with a slight bit of damage on the largest plant. You can just see it on the larger leaves just at the back. Looks kind of like Mg or wind burn. You can also see a slight bit of damage to the tip of the new leaf growing from the first one.

You live and learn hey :) Serves me right for trying to rush everything.