TV programme growing fruit and veg using LED's

[atoll]

Just watched a short TV report on an experiment using approx 5 red to 1 blue LED's to grow things like tomatoes. The professor being interviewed stated the tomatoes being grow prefered a combination of red and blue LED's. Although he never meantioned the ratio of each from what I could see of them the were approx 5 reds to blue. He went on to say they are getting excellent growth rates and are very healthy. The tomatoes grown in a green house aslo get sunlight during the day with the LED's on at night with just a 2 hour rest period when they are in the dark.

[SantaMonica]

Yes that sounds like a standard plant-grow LED.

[atoll]

Yes that sounds like a standard plant-grow LED.
So just what if anything is the difference between the best light to grow GHA and terestrial plants? There is plenty of blue in sunlight and it's the last colour to be filtered out in salt water so shouldn't we be using it to grow GHA along with red?

[SantaMonica]

The GHA we want grows mostly intertidal, attached to rocks in the waves. Here the red is very strong. And from experience, adding blue just does not help that much, and makes it much harder to build.

[atoll]

The GHA we want grows mostly intertidal, attached to rocks in the waves. Here the red is very strong. And from experience, adding blue just does not help that much, and makes it much harder to build.
Understood however the blue is still there along with more or less the full spectrum of light it's just that the red isn't getting filtered out as it would lower down the reef but all the other colours are still there. If GHA does indeed grow best with just red then fine but why I am not sure.

[SantaMonica]

That's what green is: White minus red. Since GHA absorbs so much red, the remaining color reflected looks green.