Light Quantity vs Light Quality Evidence ... Just for 4 u gg lol!

Do you think quantity is more important than quality

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Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
There seems to be a lot of confusion in here about what the actual truth is, with regards to the importance of spectrum as I have stated numerous times light quantity and light quality go hand in hand. Plenty disagree citing science journals, me personally I like to deal with real world facts I have observed, so for those of you who are interested in truth see the experiment below ...and yes I know it is not a canna experiment but I will present that data in due course:peace:
 
Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
Experiment to grow tomatoes under artificial lighting



Species of tomatoes grown:

Gardeners delight small cherry type variety.



Introduction

This first part of this experiment was created to test the effects of a low CRI Hps spectrum vs High CRI warm - coolish white spectrum at similar levels of light to see if there were any noticeable differences when fruiting tomatoes.

The second part of this experiment was to test the theory of whether “more is better” 2 LED panels of different wattage draws were tested against each other using an equal mix of warm & cool white COBs to test whether there is a point of diminishing returns – I.e could it be that more power does not necessarily equate to better growth.

The purpose of this test was about looking into ways of optimizing light with regards to growth.



Method

Three Tomatoes (1 tomato per lamp) were potted in 6 inch pots, with peat mix and small rockwool cubes ratio 5:1.

The tomatoes were taken from cutting rooted, then transplanted and grown in the vegetative phase for 6 weeks under 300 watts of cool white CFL using a photo-period of 16 hours of light 8 hours of dark. During this time they were pruned twice and then finally for a third time to exactly the same height.

Before the tomatoes plants were flipped into flowering all 3 were similar in size and stature.

The tomatoes were then switched to the flowering phase using a photo – period of 12 hours light 12 hour’s dark.

Tomato plant 1

This plant was grown using the following measurements;

219watt LED fixture with an equal mix of 3.5k & 4k 90CRI LEDs.

23,100 lumens@30cm distance dead centre

583umol@30cm distance dead centre

Avg350umol@30cm height in 50cm/sq grow area

DLI (Daily Light Integral) across canopy 15.12 (or 15.1mols per day)



Tomato plant 2

This plant was grown using the following measurements;

152watt LED fixture with an equal mix of 3.5k & 4k 90CRI LEDs.

15,750 lumens@30cm distance dead centre

380umol@30cm distance dead centre

Avg 195umol@30cm height in 50cm/sq grow area

DLI (Daily Light Integral) across canopy 8.424 (or 8.4mols per day)



Tomato plant 3

This plant was grown using the following measurements;

680watt HID fixture high pressure sodium dual spectrum lamp.

90,000 lumens

950umol@30cm distance dead centre

Avg 370umol@80cm height over 50cm/sq grow area

DLI (Daily Light Integral) across canopy 15.984 (or 16mols per day)
 
Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
Flowering/Fruiting time results

After 7 days the 219watt LED fixture was first to show signs of flowering. This was followed by the 152watt LED fixture which took 10 days to show signs flowering. And in third place the 680 watt HID fixture took 16 days.

By day 59 the 219watt LED fixture had finished producing its first batch of fully formed tomatoes. And by day 87 it had finished producing its 2nd batch of tomatoes.

By day 61 the 152watt LED fixture had finished producing its first batch of fully formed tomatoes. And by day 89 it had finished producing its 2nd batch tomatoes, initially growth was slower until feed was increased then so did the size of the tomatoes.

By day 69 the 680watt HID fixture had finished producing its first batch of fully formed tomatoes. And by day 76 it had finished producing its 2nd batch of tomatoes which showed good uniform growth.



Total yields produced as follows;

  • 219watt LED fixture = Batch 1 = 223 grams + 188 grams =411g

  • 152watt LED fixture = Batch 1 = 205 grams + 209 grams =414g

  • 680watt HID fixture = Batch 1 = 185 grams + 134 grams = 319g

  • Conclusion the fuller spectrum of the LEDs both outperformed the Hps and in the case of the tomato grown under 150watt LED it did so using virtually half the DLI of both the 220watt and the 680watt fixtures so clearly there is a point of diminishing returns. And clearly spectrum makes a difference.

Size and look of the tomatoes;

  • 152watt LED fixture produced a ratio of roughly 9:1 or 28 large to 3 small tomatoes. The colour of these tomatoes were bright red, see pics below.
 
Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
Taste and smell of the tomatoes

  • 152watt LED fixture produced really sweet and lovely tasting tomatoes, the little ones were a bit tart and sharp, and overall the tomatoes didn’t have much of an aroma

  • 219watt LED fixture again produced really sweet and lovely tasting tomatoes, the little ones were a bit tart and sharp, and the tomatoes didn’t have much of an aroma

  • 680watt HID fixture produced nice sweet tasting tomatoes, although they didn’t have much of an aroma

  • Conclusion: The HID tomato had a slightly stronger aroma than both the LED lamps, but both the LED lamp tomatoes had a much better flavour and a sweeter taste.


Conclusions

I expected the plant grown under the 680watt HID fixture, would have heavier feed/watering requirements than the LED fixtures surprisingly this was not the case. On average during the first 6 weeks of flowering the tomato plant under each LED fixture, needed watering every 48 hours with 600ml of solution, whereas the HID fixture was every 60 hours with 600ml of solution.

The plants grew quicker and more vigorously under the LED fixtures as can be seen in the timelapse video, and I believe this is why they had a higher feed/watering requirement than the plant grown under the HID lamp.

The plant grown under the HID produced a more uniform sized tomato. The ratio of larger tomatoes under this lamp when compared to the LED fixtures was higher. Because everything else was pretty much the same as the 219watt LED in terms of light delivered to the plant, but the only significant difference was the spectrum therefore my assumption is spectral output could have played a role in the higher uniformity rate, although this theory would need to be tested over a much larger sample to see if it holds up.

The LED grown tomatoes with their beyond PAR spectrum not only out-yielded the HID lamp but they using less light and they also produced a far better tasting crop. So clearly in the case of this experiment spectrum is very important to the optimisation process.

Note: I have noticed this with other beyond PAR spectrum's and I will post the datasheets of those I have previously tested in the coming days when I get some time.

I am sure if those of you who have switched from HID to LED think back then you will likely remember what the quality of your HID crop was like vs your LED crop and I am sure you will come to the conclusion that a fuller spectrum produces better quality ...but do not take my word for it run your own experiments and see for yourselves.
 
S

Shugglet

Well-Known Member
I followed a bit of the shitstorm of a thread that has led to this particular thread. I just dont think this experiment is really going to help you prove your case.

For instance your weight conclusions. How can / should that be extrapolated to cannabis cultivation?

Should one expect to get ~30% more yield out of your system that uses ~80% less power (152w vs 680w yields)? Sounds a little too good to be true I would think...
 
Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
Shugglet said:
You probably shouldnt test them yourself. Best to do a blind test with random participants. Of course this is only if you care about the integrity of your results.
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Of course I do which is why I implore people to do their own tests just like I have...I did a blind test with 3 participants with regards to taste and all 3 picked one of the LED tomatoes, I know it is not a massive sample but I went into the experiment with no expectations and came out surprised in certain areas like the feed rate of the LED tomatoes.

I have frozen the tomatoes and when I get time I will look to have them lab tested because I am willing to bet therre is a difference with regards to nutritional values... when I have that data I will present the results here as well.
 
Johnnycannaseed1

Johnnycannaseed1

Well-Known Member
I have done previous test on canna when I was a smoker and I noticed the differences but unfortunately at the time I was not interested in saving data, but I will do trials just to prove some points, some here know what I am talking about with regards to differences, others are just plain pretending or being mislead, The whole point is to further peoples understanding by getting out there for real ...not reading science journals and quoting off that like it is the Gospel truth.
 
S

Shugglet

Well-Known Member
Johnnycannaseed1 said:
I have done previous test on canna when I was a smoker and I noticed the differences but unfortunately at the time I was not interested in saving data, but I will do trials just to prove some points, some here know what I am talking about with regards to differences, others are just plain pretending or being mislead, The whole point is to further peoples understanding by getting out there for real ...not reading science journals and quoting off that like it is the Gospel truth.
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To get reliable, usable data though would be a massive experimental undertaking.

Then you factor in the differences between different LEDs and differences between strains and it wouldnt surprise me if your margins of error made the experiment borderline useless.

Johnnycannaseed1 said:
Yay another one who gets it..:clap:.

Keep spreading the word so we can get some actual truth up in this joint, rather than all this heresay Pseudo science that has been going on of late.
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The irony in this post is palpable.
 
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