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Rudolph

So over the winter I've been doing a lot of research on the light spectrum and how it effects your plant throughout its life and I found something interesting I'd like to share, what drives germination? Water and warmth? Yes but what else drives it? Light! Hence if you sow your seeds to deep your seeds have a harder time germinating, your seed won't waist there energy to germinate if it has to climb through 4 inches of dirt, so what wave leigh drives germination? As most people might know the light spectrum is large and the light that helps drive photosynthesis is called PAR (Photosynthetically active radiation) which is 400-700 in the light spectrum above 700 you get into light that is dark red, below 400 you get into uv light, both those lights have benefits to your plant but that's another topic what we're trying to find is what light wave leight triggers your plant to use it's stored energy to germinate.... Red light in the 600-700 range it's important you don't go over 700 this will have ill effects on germination, so how can we apply this knowledge? Most growers soak there seeds before planting them, if you put a red grow light on your seed during the duration of your soaking process you'll trigger you seed to start the process of germination it will give you a higher percent chance of a successful germination.

3/19/2018 12:18:09 AM

Oak Grove, Mn

Interesting Josiah, I have never done any experimenting with spectrums and germination. I know that the red light will induce flowering in tomatoes..never thought about what it does for germination. Do you have any charts of what the spectrum looks like for a season. I have heard that the spectrum changes depending on the time of day, but I am wondering if it changes by day length and sun height. I have a PAR meter...have shopped for a spectrometer.

3/19/2018 5:54:14 AM

Rudolph

In full sun you'll have almost a level spectrum think of this as all the switches being on, in the morning and evening you'll have very low light in the 400-450 range (blue) which is why the sunrise and sunset are red/pink, if it was a sunny day out you'll have a even spectrum but if you were to go in the shade you'll have almost no blue in the spectrum with no blue in the spectrum your plant will believe it's under a leafy canopy and will grow tall to get out of the canopy, this is one way you can manipulate plant size with artificial light, by using a spectrum that has no blue you'll get very tall plants.

3/19/2018 7:29:21 AM

Rudolph

The reason you don't want far red in the spectrum during germination is under a leafy canopy you get almost no blue but you also lose some red not all but some because plants don't use a lot of far red it passes through the canopy so by using dark red(far) your seed will believe it's under a canopy and will not waist the energy to germination.

3/19/2018 7:37:27 AM

Western NY

Very interesting!

I'm guessing intensity matters too? I wonder if there's a more pronounced effect in white seeds as compared to the tan ones, which might block out more of the light.

3/19/2018 8:56:42 AM

Menomonie, WI (mail@gr8pumpkin.net)

Phytochrome and Cryptochrome

3/19/2018 1:15:36 PM

Guelph, Ontario

Some species need light to germinate. Usually small seeded plants. Research shows max germination of C.maxima (giant pumpkin and squash) to be about 30C, and no effect of light.

https://www.sciencedirect.com/science/article/pii/S025462991500232X

3/19/2018 1:19:01 PM

Oak Grove, Mn

I looked at the article...that might be an incomplete study. It says : Light was provided by six OSRAM DULUXSTAR light bulbs (14 W/840, 220–240 V, 116 mA, 50/60 Hz). I looked these up...compact florescent bulbs. Even with 6 14W bulbs, I don't think they would have enough intensity to affect a thick shell like pumpkin seeds. If I am reading the data correctly, it looks like the C. maxima had nearly 100% germination with both light and no light at 240 hours..that is ten days. How many growers want to wait ten days for their seed to germinate. I am sure I am not reading all the info correctly, Next winter maybe we could set up a more distinct test for AG's....use high PAR LED lights and compare germination rate by time for dark, blue light only , red light only, and full spectrum. Would need at least a couple hundred sacrificial seeds out of the same pumpkin to do to the test.

3/19/2018 4:03:39 PM

Little-TON - Colorado

All very interesting. Yes light intensity is a big factor to consider. Wanna really get into it - try growing soft corals and salt water invertebrates with artificial light. There are Actinic florescants that put out 400nm wave length, same lights used in tanning booths....a bit lower than black lights... All very interesting to grow something half plant half animal.

3/19/2018 5:00:26 PM

Warwood

In the area around WV and as far north as Barnesville, OH that would be about 40 Latitude. Below this area tends to have sun that burns leaves and I've either needed to use 6 mil greenhouse plastic with about 40% shade or shadecloth at 40%.
If not it gets like a humid jungle between 11a-5p I need to shade out whatever spectrum I'm getting between this time. I mostly block out the penetrating overhead damaging light. At least need to cover new vine tips if not you'll have a cooked plant. I believe it shuts out ultraviolet range. Very interesting discussion. I'll experiment some and present what I've found.

3/19/2018 7:34:06 PM

Guelph, Ontario

For seed germination in seeds that require light, it is a trigger effect of red light. Not an intensity effect. This can be sensed at quite low levels. Even by seeds under some soil. Pumpkin seed shells do transmit light. Shell a seed and put a light source behind it. If light was needed to trigger germination, there would be no germination under no light conditions.

3/19/2018 11:36:06 PM

Rudolph

You are correct that you don't need light to germinate a pumpkin seed irischap, the idea I was trying to get across is if light does benefit the germination process of a pumpkin seed it might be a good idea to use a light on a 10 year old seed or a 500 dollar seed if it will give you greater odds of germination.

I'm running tests right now and will do so a few more times as the summer progresses I'll share my results at the end of the year.

3/20/2018 12:28:39 AM

Guelph, Ontario

For tests, be sure to use same seed in each group. Also be sure temperature is the same in both groups. Most lights produce heat, and you want to be sure it is not a confounding variable. Research on seed germination has not shown any benefit of light intensity or duration on light insensitive seeds. But it is always fun to do experiments. Here is a nice reference you may want to look at "Seeds : physiology of development and germination" / J. Derek Bewley and Michael Black.

3/20/2018 8:47:30 AM

Central Illinois

I wonder if light travels through the seeds edge, it appears to be a different material than the shell

3/20/2018 10:28:57 AM

Rudolph

Irischap-I'm using LEDs for the tests I have 12 lumi grow lights set up at different heights and wave leights even if there's a difference between the lights it won't be conclusive because there needs to be multiple tests.

Baitman-I actually thought about that but haven't tried it yet it makes sense that it would add in light passing through the seeds shell.

3/20/2018 7:12:47 PM

JACKSON, WISCONSIN. ; )

Interesting....

3/22/2018 8:29:34 AM