so instead of long slow electricity usage you get super spikes every 200ms? wouldnt that strain the hell out of your equip?
Exactly right SnS. You overdrive the LED's for a shorter period of time. The LED's are fine with this, as long as they are pulsed for the correct duration so they dont burn out (Most LED sompanies give pulse time and rate for overdriving LED's). The paper proves that with 100us pulses, photosynthesis remains 100% of that with constant light. Were not trying to trick the plants by "flickering" the lights, merely providing increased amount of light over a shorter amount of time by overdriving them for 100us pulses.

but is turning on/off so many times going to hurt the leds?
LED's can turn on in 200ns. There is no harm done to the LED's by pulsing them, it actually increases life expectancy (if overdriven than life expectancy stays same).

Opie- Photosynthesis only happens so fast(but still very fast)...its not like the more light you give it the more it will grow(there is a linear relationship between amount of light provided and plant growth, up to a point). Plants require certain amount of photons per unit time to attain cellular reactions for light cycle, sugar creation, ect.

this is from the paper:
Much of the light used for photosynthesis by leaves within canopies is from sunflecks (Pfitsch and Pearcy 1989; Pearcy 1990). These sunflecks range from milliseconds to minutes in duration and their photon flux densities can be as bright as full sunlight.

So plants undergo photosynthesis naturally with these "pulses" of light.

Also from the paper:

We measured photosynthesis under light/dark times of 15/135, 7.5/142.5 and 1.5/148.5 us which required instantaneous pulse PFD of 500, 1000, and 5000 pmol mp2 s-', respectively, to achieve an intcgrated PFD of 50 pmol m-2 s ' .

Basically this confirms what you guessed Opie, that there is still the same amount of light reaching the plant by pulsing the lights at a greater power.

The photosynthetic apparatus integrates the pulsed light and uses it as effeciently as continuous light

Thus saying pulsed light for photosynthesis is just as effecient at continuous light.

So say we have 200 5W LED's (as my plans are). By pulsing them at a 10% duty cycle, the actual power used y the LED's is only 100W compared to the original 100W. However we are providing the LED's with more power (from 1000mA to approx 2500mA), so the power used would be approx 1/5 of the original, saving 800W of energy. The plants still received the required amount of photons for photosynthesis, but with way greater effeciency by pulsing the LED's.

Of course I do not take every word of this paper and assume it is true, I am merely showing how pulsing LED's could be used for greater effeciency. I created a simple 555 timer circuit and hooked up 7 LED's to it and pulsed them at the required specifications (100us on, 900us off, 5kHz), and recorded the power consumtion, and indeed there was an increase in effeciency (by that I mean less watts used by the LED's). The effeciency does not come from giving the plant less light, but form giving the LED's a smaller total energy consumption. Hope Im was able to clear some thing up without confusing anymore people.

Look at the top left of pg 265 of that site....nice graph showing increased photosynthesis with increased photon density (amount of light in the pulse).