Indoor LED 350Watt leaf burn or what?

[auto-p]

All I can tell you is I think single spectrum growing is foolish and you will get diminished results from it. I have always grown mixed spectrum, mainly with red and blues no matter the lighting type. You can look up the specs on blackstars anywhere on the web if you want info on the nm ranges I use. Your personal experience with coral may be extensive, but it means nothing to me as I have no way to verify that. I was asking for a solid link to back up uvb damage from standard grow lights used by pot growers, not for a shift in conversation. Not trying to be rude, just want the uvb mystery cleared up.

You're right hugo, there does appear to be more going on than just P but like I said, I've had P damage like that before. I also see purple in some of the stems. There does appear to be a Mg problem as well, and some yellowing starting to come up from the bottom that might be N. A full plant picture would be much better but I think we're all in agreement here, PH is the culprit! That bastard PH that strikes in the night.

As for actual damage from a grow bulb-- I could burn one of my own plants as a demo for you. I have more going right now than I need. And I've done it before using a 1000W MH at 20000K... From my notes the "bad" area started around 70cm distance from the bulb. Typically the leaves start to die at the tips first, drying very rapidly, and curl away from the light. Am I positive it was UVB that caused the damage? No, but my experience led me to that conclusion:

UVB is used as for sterilization, since it damages cells and DNA. A project I recently did analysis for was for a water sterilization unit using 320nm LEDs.
We would run different cell types through a 4 watt test chamber, then regrow the cells in an agar medium. Amazing how effective UVB is for destroying cells-- bacteria, yeasts, algae, macro algae, and higher plants (like kelp.) i dont know of any reason why cannibis migt be more suitable for growth under UVB... But I doubt my employers would like me testing cannibis...

For negatives for UVB in general on plant health, DNA damage, etc. --- this is very well documented, in many many journals. Ionizing radiation cleaves DNA strands, stressing the plants repair system, causing cancers and cell death.

 

[Muddy]

Getting way off topic here. Remember, this is Venars thread regarding the problems with his plants, not a discussion of LED lighting.

 

[Nelson]

I agree with Muddy get some idea of the pH and it will either confirm or eliminate the first place a grower looks when the plant is in trouble. Light spectrum has nothing to do with it. Keep an orderly mind like Muddy does and check the first place you should look when you have a problem - pH.

 

[autoberry]

I've seen burns from UVB-- both plants and corals from MH bulbs. Usually from high spectrum bulbs (20000K.). Close to the bulb, UVB levels are really really high, and can cause chromosome damage and cook offs.

You know, you might be able to help me out. --- I'm designing some LED lamps for growing right now, and I'm looking for some scientific data on grow spectrums... Unfortunately, I can't find any. Everything in this hobby seems to be anecdotal only, which as far as I'm concerned, is useless. (or less than useless--)

I have chlor A and chlor B and caratinoid data. But what everyone chats about doesn't seem to actually have anything to do with actual absorption spectrums. I'm looking for studies on THC and cannabinoid production specifically.

My last personal grow was under 1100 watts of LEDs, mainly 420nm Cree, and Cree broad spectrum whites.

In my current grow, I'm using the same 1100 watts, but more spread out, with more plants. Didn't seem to change a thing-- if anything my current grow is larger at five weeks than my previous grow. (but probably due to temps being about five degrees warmer in my grow room this time of year)

After this grow is complete, I'll be changing over to Osram horticultural 670nm LEDs. I want to see what happens when a grow occurs with only a single spectrum-- and if it changes anything.

Thanx!

you want the data on what spectrums to use.......look at..........quantumledbloom spec ranges. ill vouch they are on target "At Peak" chloroplast absorption specs.......

 

[autoberry]

Ps;..............Muddy, its cal/mag def.............most auto's get it in soil grows under poky led's etc...............as they go mental for anything they can eat up into sugar !!........