wordwiz said:
Omri,
I do choose to ignore you! No hard feelings or animosity, it's just mostof the readings I have done say PAR light is important, as is the amount of LUX. I'm sure you know what LUX is and the more lumens a plant receives, the better - at least to a point. Consider this before stating Lux is not important: Calculations based on a model made by PPO, show that tomatoes cultivated in the Netherlands, lit with 10,000 lux can produce 92 kg/m2 annually, and with 15,000 lux it is possible to produce 104 kg/m2. (This was a study dealing with using lighting in addition to the sun - you can read one study here:
http://www.pllight.com/horticultural/sampleapps/vegetables.php )
With a higher amount of LUX, I do not need to keep the lights very close to the plants - a consideration when I have six inch cucumbers growing next to 1/2 inch tomatoes or peppers. There is enough light reaching the plants that they do not get leggy.
As for PAR, I believe what NASA and hundreds of reserches have said - plants absorb red and blue light while not absorbing yellow, green or violet. It seems quite foolish to waste electricity that will be used to excite phosphors that produce green and yellow light if my primary purpose it to promote plant growth.
I have no doubt one can achieve decent plant growth using 5000K lights and anyone who wants to certainly may. But science says while it makes the plants look better to the human eye, the light is not as efficent per watt. Here's what one lighting expert (from Envirolite) states: The main value of the PAR measurement is that it is the only measure that takes into account the actual light and light colours that the plant uses to energise its pigments and generate sugar energy, and it’s the sugar that makes your plants grow and produce such sweet fruits!
I will grant you that most reports say that 5000K lights tend to promote vegetation better but I am not finding that to be true. They are not as tall as plants that have been under 5000K lights but their leaves are larger.
YMMV and you are apparently doing a good job growing peppers. With all respect and in friendship, I feel it is best to let you run your railroad and I'll run mine!
Mike
wordwiz said:
Try growing plants under 700 lux of lights or use lamps that provide 100,000 lumens of violet wavelength light. Let me know your results.
To avow that lux or PAR is not important is doing a disservice to people who may not know better.
Again, no animosity. Just a difference in opinion, beliefs and experiences.
Mike
Let us first focus on PAR, shall we?
You apparently think the data I'm giving is "magical" or whatever. I too rely on science.
Fact. when measuring PAR there's no distinction between the different wavelengths used by plants.
Fact. different wavelengths result in different levels of photosynthetic activity, which means different levels of energy.
Fact. different wavelengths encourage different types of growth in plants, due to the fact the use of energy is mainly determined by the color of light they're getting.
Fact. both Chlorophyll a (the main pigment in both quantity and energy converted) and the Carotenoids absorb violet light.
In the past seven (7) months I've been testing different light sources (LEDs, CFLs, HIDs and several more), and within those different "groups" I compared the use of different wavelengths and overall light temperature.
When providing enough lumens, even the least efficient wavelengths showed growth. while red and blue separated did show growth, none of them showed the same healthy growth the plants getting a wider spectrum showed. it is important to say the results were somewhat identical in every other light source (when considering the variables). bulbs were compared to an equivalent bulb with the same wattage consumption and different spectrum.
Science tells us that providing 20W of a wavelengths providing only 20% of the photosynthetic activity is not as good as a 10W of wavelengths providing 80% of the photosynthetic activity.
Wattage efficiency is definitely not the main factor. just look at LEDs.
The general term of PAR is not important. the actual wavelengths are.
Now let us move to Lux.
Just to make things clear, Lux is unit measuring illuminance or how much visible light there is per square meter.
When using bulbs besides placing the bulb right on top the plants, there's nothing else you can do to increase Lux. for that reason alone, Lux is not important when growing with bulbs.
There isn't a certain amount of Lux required by the plant to do anything.
More of a certain light will be better, but not necessary. the same principal is what makes a 50W bulb better than an equivalent 25W. same with 400W, 600W, 1000W etc.
Like I already mentioned above:
Science tells us that providing 20W of a wavelengths providing only 20% of the photosynthetic activity is not as good as a 10W of wavelengths providing 80% of the photosynthetic activity.
Wattage efficiency is definitely not the main factor. just look at LEDs.
First you need to make sure you have the right wavelengths, only then worry abut if you have enough of them.
A good HID could easily provide more Lux than a not so sunny day, but the sun will still be better. why? because of the wide spectrum.
Giving a plant a lot of the wrong wavelength, won't make it healthier.
Lux is really not something you should be worrying about when growing with bulbs. therefor Lux is not important.
Mike, I like our little discussions and I already made peace with the fact you're confident you're right.
