CMH and hps breed genes?

superpedro · May 30, 2018

I'm thinking about replacing my 600w HPS wit 2x315 CMH.
But has anyone noticed if landrace, or something breed not too far in generation from outdoor breed strains, show more benefits than those strains derived from many generations of HPS breeding?
My thought was, perhaps in selection under HPS, there would be a tendency to select and promote genes, better suited to deal with the "wonky" spectrum. And perhaps something good gets thrown because of more dependency to the full spectrum?

Natural high · May 31, 2018

I bought 2 x 315w as an alternative to 600w of hps and I have found that sativas and sativa leaning hybrids grow better for me under HPS than CMH. Under HPS they get long branches with solid buds (with very little leaf) up the length and a big long cola at the top. Under CMH I get very little stretch so the nodes end up close together, more like a leafy indica with only the top bud a decent size.

With HPS, the copious amounts of red light make the plant focus on flowers before leaf. This is more like Autumn sunlight, whereas CMH is more like midday in Summer. If I had to pick only one light I would choose the HPS.

Hope this helps.

.

superpedro · May 31, 2018

It helps

Not surprised there will be both pros and cons.
My only personal experience with fullspectrum, was the cfl microgrows I did for a short period 5-6 years ago. And for obvious reasons, I never tried tall sativas doing micro.

Did the CMH do anything positive for your sativas? Taste, color, effect?
Perhaps some strains could benefit from a late stage switch?

Koondense · May 31, 2018

Hi superpedro,
i think your reasonong is correct, i also believe indoor selections are always impacted by type of light used.
As NH said, the difference in leaf/bud ratio should be there but still i think the better spectrum is from cmh lights, more similar to sunlight so i would definitely go for a all cmh setup. There's a thread with side by side growing with 1000w hps vs 630 cmh in the equipment section, i suggest you take a look and see the differences in almost real time.
By the way, the spectrum changes in sunlight between summer and autumn are a myth, not reality.

If you go with cmh and primarilly aim for flower production i would suggest the 3100K bulb.

Cheers

Natural high · May 31, 2018

superpedro said:
Did the CMH do anything positive for your sativas? Taste, color, effect?
Perhaps some strains could benefit from a late stage switch?

The CMH gives better frost and terps if the grow temperatures are higher, but the difference is negligible when cooler. Taste and effect are similar. One other thing I have observed with CMH is the pistils will wither earlier than with HPS, with the buds appearing ready about a week earlier.

Koondense said:
By the way, the spectrum changes in sunlight between summer and autumn are a myth, not reality

Spectrum change with season, or time of day, or change of latitude is definitely not a myth. It all has to do with the angle of the sun relative to the surface (elevation angle). When the sun is relatively low in the sky, the sun has a long passage through the atmosphere. The longer the path, the larger the proportion of scattered radiation. Since the shorter blue wavelengths are more prone to scattering, the sunlight reaching the surface has a higher proportion of red when the sun is at a lower angle.

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superpedro · May 31, 2018

Natural high said:
The CMH gives better frost and terps if the grow temperatures are higher, but the difference is negligible when cooler. Taste and effect are similar. One other thing I have observed with CMH is the pistils will wither earlier than with HPS, with the buds appearing ready about a week earlier.

Spectrum change with season, or time of day, or change of latitude is definitely not a myth. It all has to do with the angle of the sun relative to the surface (elevation angle). When the sun is relatively low in the sky, the sun has a long passage through the atmosphere. The longer the path, the larger the proportion of scattered radiation. Since the shorter wavelengths are more strongly are more prone to scattering, the sunlight reaching the surface has a higher proportion of red when the sun is at a lower angle.

Thanks.

Yes I know about the daily change, particularly in the far-red spektrum. Fun fact, in the greenhouse industry where I used to work, regulating the f-red amount in a daily pattern was used to limit stretch in flowers.
They also came up with a way to keep a daisy in the bud-setting fase, by giving it an hour of pure blue before and after the normal light period.
Wouldnt be surprised if plant manipulation through light patterns became a topic among cannabis growers at one point.

Koondense · May 31, 2018

Natural high said:
Spectrum change with season, or time of day, or change of latitude is definitely not a myth. It all has to do with the angle of the sun relative to the surface (elevation angle). When the sun is relatively low in the sky, the sun has a long passage through the atmosphere. The longer the path, the larger the proportion of scattered radiation. Since the shorter blue wavelengths are more prone to scattering, the sunlight reaching the surface has a higher proportion of red when the sun is at a lower angle.

View Image

.

That graph seems fishy to be honest, can you put a source for those measurements? That would be helpful, I couldn't find the source.

This graph is way more similar to my measurements(did that once) and indicates some loss of blue, at the same time much more loss of total photons, also reds(almost proportional). The scattering is real but the scattered photons intensity is a few magnitudes lower than the sun's disk intensity.

im824-1024px-spectrum_of_sunlight_en-svg-png.164020

Source for measurements:
https://www.avantes.com/application...ar-irradiance-and-solar-uv-field-measurements

+ an interesting simulator
http://cprm.acom.ucar.edu/Models/TUV/Interactive_TUV/

This and my measurements correlate + many other reasons, so I will not believe the spectrum change claims until there's solid evidence to prove it.

Cheers

superpedro · May 31, 2018

Koondense said:
That graph seems fishy to be honest, can you put a source for those measurements? That would be helpful, I couldn't find the source.

This graph is way more similar to my measurements(did that once) and indicates some loss of blue, at the same time much more loss of total photons, also reds(almost proportional). The scattering is real but the scattered photons intensity is a few magnitudes lower than the sun's disk intensity.

View Image View Image

Source for measurements:
https://www.avantes.com/application...ar-irradiance-and-solar-uv-field-measurements

+ an interesting simulator
https://cprm.acom.ucar.edu/Models/TUV/Interactive_TUV/

This and my measurements correlate + many other reasons, so I will not believe the spectrum change claims until there's solid evidence to prove it.

Cheers

To be fair, the diagram you posted used measurements in an only 14-day timeframe. Not saying anything about your personal measurements or what is right or wrong, but I believe this diagram is unusable to support your claim about seasonal change.

superpedro · May 31, 2018

Here is more about the light pattern manipulation I mentioned. For use in greenhouses, you can find F-red filter curtains.
Off topic by a long shot, and not a study on cannabis. But for those who find the stuff interesting.
http://hortsci.ashspublications.org/content/42/7/1609.full.pdf

http://www.nrcresearchpress.com/doi/abs/10.1139/cjps-2016-0089

http://www.pcsierteelt.be/hosting/pcs/pcs_site.nsf/0/08E05EAACA9C5708C1257CFB003C1BB2/$file/Dierck%202017%20Light%20quality%20regulates%20plant%20architecture%20in%20different%20genotypes%20of%20chrysanthemum.pdf

But lets get back to CMH and plants reaktions

Natural high · Jun 1, 2018

Koondense said:
That graph seems fishy to be honest, can you put a source for those measurements? That would be helpful, I couldn't find the source.

This graph is way more similar to my measurements(did that once) and indicates some loss of blue, at the same time much more loss of total photons, also reds(almost proportional). The scattering is real but the scattered photons intensity is a few magnitudes lower than the sun's disk intensity.

Cheers

I don't have a source for the original data but I used the graph as it demonstrates the shift in spectrum in simple terms. This graph differs from yours in that the y axis represents relative spectral power with 560nm as the normalised wavelength. Yours measures total solar irradiance but only covers a two week period as pointed out by superpedro.

I found another graph of data from your same source which better illustrates the shift in spectrum with change of elevation angle.

https://www.avantes.com/application...ar-irradiance-and-solar-uv-field-measurements

These are measurements are taken throughout the day in the same location. For the highest measurement on the graph (1.12pm), the sun was at an elevation angle of 58.5 deg whilst the lowest (8.20am) was at 20.5 degrees. The shift in spectrum over this range is clearly observable in the flattening of the curve as the sun's angle falls lower.

A good experiment to demonstrate the effect of elevation angle would be to measure the irradiance throughout a clear day on the equator at the equinox. That would give the full range from 90 deg at noon down to sunrise/sunset. At my location at around 33 deg south, the sun is at an elevation angle of 80.5 deg at noon on the summer solstice, 57 deg at the equinox, and only 33.5 deg at the winter solstice. I expect that there is a significant change in spectrum over the year in my location.

Cheers
.

troutman · Jun 1, 2018

Metla Halide is closer to natural sunlight than HPS and why it's all I use for Sativas. :tiphat:

Been using the 7,200 K 600W MH kind of bulb.

Natural high · Jun 1, 2018

superpedro said:
But lets get back to CMH and plants reaktions

These two photos are of the same Jack Herer clone grown under HPS and CMH. The HPS photo is at 7 weeks and the other at 4 weeks, but I still think they show the different response to the different spectrum's.

HPS - longer internode spacing and a high flower to leaf ratio

CMH - short internode spacing and a relatively greater leaf to flower ratio

Cheers

superpedro · Jun 1, 2018

Natural high said:
These two photos are of the same Jack Herer clone grown under HPS and CMH. The HPS photo is at 7 weeks and the other at 4 weeks, but I still think they show the different response to the different spectrum's.

HPS - longer internode spacing and a high flower to leaf ratio
View Image

CMH - short internode spacing and a relatively greater leaf to flower ratio
View Image

Cheers

Very nice buds, a the difference tells a lot

superpedro · Jun 1, 2018

Natural high said:
I don't have a source for the original data but I used the graph as it demonstrates the shift in spectrum in simple terms. This graph differs from yours in that the y axis represents relative spectral power with 560nm as the normalised wavelength. Yours measures total solar irradiance but only covers a two week period as pointed out by superpedro.

I found another graph of data from your same source which better illustrates the shift in spectrum with change of elevation angle.

View Image

https://www.avantes.com/application...ar-irradiance-and-solar-uv-field-measurements

These are measurements are taken throughout the day in the same location. The shift in spectrum is clearly observed in the flattening of the curve as the sun's angle falls lower.

A good experiment to demonstrate the effect of elevation angle would be to measure the irradiance throughout a clear day on the equator at the equinox. That would give the full range from 90 deg at noon down to sunrise/sunset. At my location at around 33 deg south, the sun is at an elevation angle of 80.5 deg at noon on the summer solstice, 57 deg at the equinox, and only 33.5 deg at the winter solstice. I expect that there is a significant change in spectrum over the year in my location.

Cheers
.

Those are great arguments.
The biggest reason for the greenhouse experiments, involving those curtains i mentioned, is the slope of the sun at winter-times in Denmark. The peak position is ok. But the duration of sunset/sundown, from the point that shifts the f-R:R balance in a negative way, takes much longer.

Natural high · Jun 1, 2018

superpedro said:
Those are great arguments.
The biggest reason for the greenhouse experiments, involving those curtains i mentioned, is the slope of the sun at winter-times in Denmark. The peak position is ok. But the duration of sunset/sundown, from the point that shifts the f-R:R balance in a negative way, takes much longer.

I could only get one of those links you posted to work. From the link it seems too much far red (relative to red) makes the plant think it is shaded, and it responds accordingly with longer internodes and bigger leaves etc.

superpedro · Jun 1, 2018

Natural high said:
I could only get one of those links you posted to work. From the link it seems too much far red (relative to red) makes the plant think it is shaded, and it responds accordingly with longer internodes and bigger leaves etc.

Don't know why they won't work?
Try google "f-red 1609.full.pdf". First link.

superpedro · Jun 1, 2018

And btw. Wasnt involved in that experiment in any way. But a lot of spinoff-products and field testing on Daisys and light have gone on since then. And I have witnessed some of the results with my previous work.

superpedro · Jun 1, 2018

troutman said:
Metla Halide is closer to natural sunlight than HPS and why it's all I use for Sativas.

Been using the 7,200 K 600W MH kind of bulb.

Thanks.
Any experience with "leafy" tendencies with sativa and MH, compared to sativa grown under HPS?

Thinking about the CMH experience posted further up.

Koondense · Jun 1, 2018

Regarding spectrum shift, it's still not as you imagine. The thing is although there's less blue of course, the relative differences are minor and the total irradiance is much lower when the sun is low on the horizon, so overall much less reds also(which is boosted in the NH's graph due to autoscaling of the graph-wrong to do).
Remember to check the autumn light and try to find differences with summer light, you will only find difference in intensity because of the angle, except if you live in the arctic circle with high pollution. Also, if you can, do some proper measurements and show us how this spectrum shift occurs.
I know nobody will do it because it's not real

The picture of the JH shows an interesting difference which could be easily attributed to the effect OP is trying to understand, the adaptation of the variety to being bred(selected) under hps.

Cheers

CMH and hps breed genes?

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