Effect of LED shoplights on tomato plants

[rwsacto]

A week later, all plants are mostly outside in the sun. The new growth on the LED plants is bright green, just like the fluorescent raised plants. The original LED leaves remain dark green and purple underneath. There is no observable difference in the size or vigor of the different plants.

Rick

[Ricky Shaw]

The garden seems to be the great leveler of things. They were good looking seedlings, and the biggest takeaway for me is viability of LED in making seedlings. They put out so little heat they would seem a perfect fit for cold treatment techniques.

[bower]

Many years ago when I was studying ecology and plant physiology, I learned that different shades of green represent slightly different (differently modified) photosynthetic pigments, which are optimal for different ecological niches, depending on the amount and quality of light. For example, the mosses and some other plants adapted to grow in the forest have chlorophyll pigments that are optimized to get the most efficient light capture in a shade situation.
Maybe tomatoes are able to adapt their pigments for different light regimes.

On the other hand, when there's a lot of purpling on the leaf, it may alter the shade of green that we perceive too.
When I've put tomato plants outdoors here (much colder) some of them will completely lose their medium green tender greenhouse foliage in the first week or so. The new foliage is always tighter and a darker green, and is really rugged to the elements.
Don't know if the colour is from modified chlorophylls, other substances/pigments eg the purpling, or maybe due to slower growth, the pigment density is a variable too...???

Just some rambling thoughts.

[WhippoorwillG]

Thank you for sharing. Big difference.

This is the second season that I have grown some trays under LEDs. The color and stature of the LED trays is somewhat representative of your results. The antho expression and whatever other color pigments are elevated far above normal levels. Very dark drab green/purple on compact stout plants.

The stature may only have to do with the intensity that can be obtained at canopy level from an LED vs a regular FL setup.

Of possibly more importance, it has also been my experience that the root systems don't seem to develop at the same rate, with the LED lagging behind the florescents. That is an observation that has repeated a few times for me, but may be rooted in my setup and not the different lights.

[PhilaGardener]

Originally Posted by bower

Don't know if the colour is from modified chlorophylls, other substances/pigments eg the purpling, or maybe due to slower growth, the pigment density is a variable too...???

The purple probably is due in large part to the accumulation of anthocyanin pigments, made as a protective response to high light levels (and perhaps the different spectrum of LED sources compared to fluorescents). It is possible that with LEDs you can leave a bit more distance between the plants and the light source and get the greener growth to which you are accustomed - LEDs are very directional in their light emission (to the point where making them more like traditional lighting sources is an engineering issue).

[Worth1]

Originally Posted by PhilaGardener

The purple probably is due in large part to the accumulation of anthocyanin pigments, made as a protective response to high light levels (and perhaps the different spectrum of LED sources compared to fluorescents). It is possible that with LEDs you can leave a bit more distance between the plants and the light source and get the greener growth to which you are accustomed - LEDs are very directional in their light emission (to the point where making them more like traditional lighting sources is an engineering issue).

They sell LED lights to take the place of regular lights in vesicles.
I am going to get some for my turn signals and brake lights for my motorcycle for the very reason you said that I put in red lettering in your post.
They are so bright that other drivers cant miss them.
I have seen these things in action.
Worth

[Hntrss]

I switched to LED after reading this thread, just after they sprouted. Plants are doing great and much cooler. Stays around 70 degrees.

[Hntrss]

So I went away for 8 days. I didn't know what to expect when I returned. I watered them good and left, hoping for the best. Any doubts about LED lights are gone! Crazy growth, especially Mortage Lifters on left. Those are 2 Lithonia single tube LED shop lights from HD. 1200 lumens each I believe

[nhardy]

I have been looking at replacing the two short fluorescent lights units with one 4 ft. led. Any one have a preference? 6000 to 6500K for color. How many lumens are you going for?

[dmforcier]

Mmm. Careful about the color. If I understand it correctly, LEDs emit in a very narrow frequency band. Manufacturers mix LED colors to give the wider spectrum that plants like. If you are looking at a replacement tube you're probably okay.

As for rated color, I would go 6500K for a single lamp - closer to sunlight. For quad fluorescent, I mix two 6500K and two 4800K(?). But frankly, I don't think it's all that important.

.

[Worth1]

Originally Posted by dmforcier

Mmm. Careful about the color. If I understand it correctly, LEDs emit in a very narrow frequency band. Manufacturers mix LED colors to give the wider spectrum that plants like. If you are looking at a replacement tube you're probably okay.

As for rated color, I would go 6500K for a single lamp - closer to sunlight. For quad fluorescent, I mix two 6500K and two 4800K(?). But frankly, I don't think it's all that important.

.

This is why the (Grow) LED lights only emit in the red and blue spectrum and not in the green of middle spectrum.
This is why you see them looking purple.
This is not to say you cant use the ones made for us you just get light the plants dont need.
When they build the LED lights for human vision they mix all three spectrum's and we see it as white or yellowish light depending on what they use.

Speaking of this some guy was on a bicycle last night with a LED head light on his head.
It almost ran me off the road.

Worth

[schill93]

Originally Posted by rwsacto

I purchased two LED shoplights for the garage but set them up as grow lights for tomato season. Tomato plants were potted up at second true leaves. The tray on the left was placed under the LED lights for about two weeks. The tray on the right was under T12 and CFL lamps for the same 2 weeks. Both were raised in 50-70 deg temps.

The plant leaves under the LED lights are visibly more bluegreen with dark stems and more purple underneath. Otherwise they appear the same for size and vigor.
A few LED plants had mottled yellow on some leaves in the third photo.

From now on, the trays will be rotated, mostly under the fluorescent lights, until set outside.

Any observations or comments are welcome. Again, these are 4 ft. white LED shoplights ($25 at Costco), not LED growlights.

Rick

Rick, We'd like to hear the end of the story. How did your Costco lit plants grow and produce once they grew up. Also the rest of you who tried the plain white LED shop lights.

[Nematode]

This is an interesting topic, there is a lot of information/misinformation about different lights.

Best I can figure plants use blue and red for photosynthesis, but also other wavelengths as inputs for day length etc.

Commercial growers try and use blue and red leds because they line up on the photosynthesis bands and are very efficient.

White leds are less efficient and more expensive per unit of light output but have a good spectrum for growing.

This link is pretty informative about spectra and light levels vs flourescent.



http://www.carnivorousplants.org/how...ghting.LED.php

[rwsacto]

Originally Posted by schill93

Rick, We'd like to hear the end of the story. How did your Costco lit plants grow and produce once they grew up. Also the rest of you who tried the plain white LED shop lights.

They grew up fine and lived happily ever after

Once in the sun, there was no difference in new growth or roots compared to seedlings raised under fluorescents.

Rick

[Ambiorix]

What are the varieties of tomatoes which underwent both treatments?