Effects of differing wavelengths of light on cana growth.

[theguyman]

I just made this with paint. This picture demonstrates the first 3 layers of a plant absorbing a full spectrum light source. Its only an approximation so bear with me.

This again shows penetration vs quality. Notice that the more layers the light goes through, the lower %Pfr will converge at. This assumes you start with a full spectrum!!! if you only have a 660nm light source, the entire plant will converge at 85% eventually which i'd say is like lowering interest rates to attract a housing bubble you're telling the lower branches their light source is perfect, when in reality hardly gets any light at all. Having the yellow there gives a contrast of %Pfr between higher and lower layers of the plant. this is one reason I think led grows tend to fail and HPS do so well. Also, the yellow itself allows bottom layers to get some light.

Edited August 31, 2009 by theguyman

[Randalizer]

Great stuff! Thanks for that theguyman!

I'll be doing a 3rd diary in the next month or so. It will have some very interesting lighting experiments going on.

[theguyman]

I made one more diagram to continue my story. This picture demonstrates the common LED grows we've seen and my analysis.

[eurasian_farmer]

2nd best read all day!!

im using 2x400HPS and 400MH.

the thickness of my stems is astounding to me. al though the lower branches havent stretched up to the light. so the buds are all tight to the stem.

Awesome, but not ideal. but these were vegged under fluros

it would seem that the idea of vegging in mh is best.

forcing flowering using hps for about 3-4 wks

then either MH til finish for potency or a combination of hps and mh for bulk and potency.

Im goin with the combination of all three and despite the tightness of the growth, It Does Feel Right!!

ef

Cheers

E2A - now im gonna read up on the UVB(reptile lights)

Edited September 20, 2009 by eurasian_farmer

[Mugwuffin]

Good read here! always been interested with the different light wavelengths an how they affect plant growth, I've just finished my led veg cabnet, might have to invest in some UV leds Also read up on NextGen ballasts Hortilux bulbs - they look amazing, shame there's no supplier in england, but did a quick search on ebay and theres a US seller who ships to england does the stright 400w NextGen ballast for £161.34 inc postage or the switchable (400W or 600W) ballast for £205 all in and the Hortilux bulbs are between £50-£60 all in, the postage is a fair bit but seems worth it considering the quality of the equipment. The 400W Hortilux Eye Blue produces 80,000 lumens, thats crazy! my 400W MH only produces 55,000, and remember the key to ebay is comunication especially with international sellers. Hope this helps peeps looking for cutting edge grow tech, I'm gonna gets me first indoor grow down before I invest in this sort of kit tho. Out of interest could I use the Hortilux bulbs with my 400W lumatech digi ?

[groovelick]

Good read here! always been interested with the different light wavelengths an how they affect plant growth, I've just finished my led veg cabnet, might have to invest in some UV leds Also read up on NextGen ballasts Hortilux bulbs - they look amazing, shame there's no supplier in england, but did a quick search on ebay and theres a US seller who ships to england does the stright 400w NextGen ballast for £161.34 inc postage or the switchable (400W or 600W) ballast for £205 all in and the Hortilux bulbs are between £50-£60 all in, the postage is a fair bit but seems worth it considering the quality of the equipment. The 400W Hortilux Eye Blue produces 80,000 lumens, thats crazy! my 400W MH only produces 55,000, and remember the key to ebay is comunication especially with international sellers. Hope this helps peeps looking for cutting edge grow tech, I'm gonna gets me first indoor grow down before I invest in this sort of kit tho. Out of interest could I use the Hortilux bulbs with my 400W lumatech digi ?

Dont forget a 240vac to 110vac transformer then if it's a U.S. product

[Randalizer]

Dont forget a 240vac to 110vac transformer then if it's a U.S. product

NextGen ballasts (I own one) can handle 90V to 260V, although you may need a plug adapter. They are designed to work with generators which usually have fluctuating voltage output.

Edited September 20, 2009 by Randalizer

[Russkya]

Just so you know what you're describing is called "photomorphogenesis" in the main and is the science of how light affects plant growth.

In higher plants the main parts of the spectrum that influence growth is as we all know red and blue. The plant has 2 different receptor molecules for it - red is picked up by phytochrome and blue is picked up by cryptochrome.

UV-B is ultimately damaging to plants and the increase in resin production is probably at cost to yield as a stress response, most plants have adaptations to get around excess UVB which tends to be pumping more pigmentation into the epidermis, it's thought that compounds called Brassinosteroids are the receptors for this.

Phytochrome

Comes in 2 flavours which are sensitive to red and far red light, the differing ratios of red to far red are taken by the plant as indicators of total irradiance, the more far red the plant receives in relation to red the more the plant is being shaded and as such far red light influences plant growth in stem elongation as it searches out for more red light - in short the more far red there is it stimulates a shade avoidance growth habit by the plant. Red light is also taken by higher plants as a major stimulus for flowering and bulb formation.

Cryptochrome

Responsible for circadian rhythm in a lot of plants and animals [like a biological clock] cryptochrome being stimulated in cannabis signals to the plant that it is in full sunslight and inhibits it's shade avoidance growth mechanism. Cryptochrome also influences guard cell turgidity and thus stomatal openings which controls gaseous exchange but on this area i'm less knowledgable.

[Randalizer]

Thanks for that!

[GreenNinja]

(reproduced from Canna UK's site - it's behind a password so I can't provide a (broken) link.

The Influence of Colours on Plants

Light is essential for every plant. Chlorophyll allows plants to convert energy from light into sugars. Does light impact plants in ways other than just supplying them with energy? Do the colours even influence a plant’s growth and development? This article reviews these and other questions.

D. Kroeze, CannaResearch

The primary colours

Researchers have traditionally distinguished seven colours, the colours of the rainbow, red, orange, yellow, green, blue, indigo and violet. We may call these the primary colours. Put together, the primary colours create white light and are visible when a ray of sunshine is split by a prism.

Objects can absorb the colours in light, let them pass through or reflect them. Science tells us that objects themselves possess the colours they do not absorb. Because plants do not absorb green they must themselves be green. There are those who claim that light measurements show that plants themselves emit light particles in the dark and hence actively help create their own colour.

Just as we do, plants sense the light and colours surrounding them – but in a different way!

Red light

Plants are sensitive to red in the light spectrum, a sensitivity that arises from the plant having what is called a red light photoreceptor. The receptor is a blue-green pigment termed a phytochrome present in the cells of a plant. You might think of phytochrome as an eye that only senses red light.

Red light impacts a plant in many ways. Plants that are grown in plenty of red light are often large, but in general are also tall with plenty of branches. If the photoreceptor picks up a large quantity of natural red light, for example in the summer when there’s plenty of natural red light, production of a plant hormone (meta-topolin) is increased. This hormone prevents the chlorophyll in the plant being broken down, so that it stays green in the spring and summer. And that is only beneficial, for it is precisely at this time that the plant needs its chlorophyll to convert energy coming from the sun into sugars.

Red light also influences a plant’s flowering and seed production.

Using the quantity of red compared to the amount of far-red in the light the plant decides whether to start flowering. The flowering period can be extended by exposing the plant during the darker period to red-containing light. It will then take longer before you can harvest which of course you don’t want! This explains why it is unwise to enter the growing area when it’s dark.

The red colour in light also influences flavour because it increases the concentration of special oils in plants. The leaves may have a more bitter taste.

If you want to get seeds from your plants, and you’re looking for possible “female” seed then you need to avoid exposing your plants to excessive red light, because this will cause many seeds to grow, “if applicable”, into male plants. Unless you want it the other way round of course.

Blue light

Plants see blue light as well as red light, using a photoreceptor that is called a cryptochrome. If there is plenty of blue light, as in nature during the autumn and winter, this receptor dampens the operation of a plant hormone called auxin. This hormone is responsible for the plant’s stem growth. Auxin is also responsible for what is referred to as ‘apical dominance’, the phenomenon whereby growth points ensure that buds do not get entwined and create subsidiary branches. This causes the plant to create more side stems when exposed to bluish light and the plant stays a little shorter. This helps us to understand why plants enjoying an early growth phase with bluish light are often squat in appearance with a more robust structure. Experiments with blue light resulted in plants that are wider than usual. This can be explained by reference to the fact that more flowering buds (more branches) could form by reason of diminished apical dominance at the growth point.

Plants use the quantity of blue light to determine how far to open their stomas. The more blue light, the wider they open their stomas, so accelerating their metabolism. High levels of blue light will therefore promote increased metabolism, and by extension accelerate plant growth and development.

Blue light is also responsible for directing leaves and growth points toward the light. Blue light also avoids the multiplication of leaves around the fruits and fertilised plants give more seeds (if applicable to the crop – more female seeds). A shortage of blue light in the spectrum will quickly cause you to lose 20% of your harvest. The optimum red-blue light ratio is 5:1.

Green light and the other colours

Plants are hardly sensitive to green light. As far as we know, they lack receptors for this colour. This is probably the case because in practice plants do not absorb this colour. Plants grown exclusively in green light will be exceedingly weak and rarely grow old.

The clear inference is that plants only sense those colours for which they have specific receptors. Plants are therefore not blind but, to a degree, are colour blind when it comes to other colours. Plants react to orange and yellow light more or less as if it were red and to indigo and violet light as if it were blue.

‘Invisible’ light

The plant on the left is taller because it received

less red light in relation to far-red light. The plant

on the right was exposed to the usual red/far-red

light relationship.

Source: hxxp://www.le.ac.uk

Although plants are a trifle colour blind, they can sense colours that are entirely invisible to us. For example, plants can perceive far-red light. Plants often exploit the red/ far-red relationship. A seed uses this relationship to determine germination. Plants also use that relationship to determine the number of other plants in the immediate vicinity. Because plants absorb large amounts of red light whilst reflecting far-red light, there will be less red light in a plant’s immediate vicinity if other plants are in the area too. Seeds will hold off germinating and the plants that are already in place will grow faster in order to emerge above the other plants, so acquiring sufficient light for their photosynthesis.

The fact that far-red light has precisely the contrary effect to that of red light makes it unsuitable as a light for growing. The traditional light bulb is a rich source of far-red light.

Ultra violet light (UV) also influences plants. As with blue light, plants perceive this colour using the cryptochrome photoreceptor. It is unclear whether other photoreceptors can perceive UV light.

If the quantity of UV light is increased, the concentration of a purplish substance called anthocyan goes up. Anthocyans protect plants against UV radiation, but also against micro-organisms trying to get in. Anthocyan build-up can often be seen where there are flaws, such as a lack of oxygen. UV light doesn’t only damage the plant’s DNA and membranes, but immediately disrupts the process of photosynthesis. Therefore an excess of UV light is unhealthy for plants.

Light is seeing

As we have seen, light is not just essential for plants when it comes to supplying energy for photosynthesis. By revealing just a small part of the story we have seen how plants use colours to regulate many of their processes. Plants are capable of perceiving those colours that matter to them. Those colours give the plant an indication of its general environment and thus its chances of survival and reproduction. If your plants are to develop, grow and flower well, the composition of the light is at least as important as its quantity. Do not forget that a plant perceives the composition of both direct and indirect light. Indirect light here refers to the light that is reflected onto a plant by other objects such as walls or other plants.

[first-timer]

Hi,

I`m only a 3 time grower but I have read a lot.

My first grow was LED whit good yield but airbuds, second was 600w hps better yield.

I did also hear that plants uses mostly red light for the flowering so this time i`m using my hps combined with 90w LED (red and blue light) thaught it might be a good idea ...?

The clones I`m using is from the same mother as my first two grow so it will be fun to watch them, their 2 weeks into flowering and looking goood,its popping out everywere

[iky]

Freinds of mine have been growing with led s, not bad results.The results of crop size comparisons are not yet confirmed as amount of lights and their hight ., heating and ventilation ., are a new area for experimentation,The benefits of leds are no detectable heat source, cheaper electric bills,Crop size comparisons I think favor led s in cost production comparison Quality seems ok happy growing eric

[iky]

http://www.ledgrowlightinfo.co.uk/How%20to%20position.html

http://www.ledgrow.eu/diy.html

Lots of info on leds here

[Randalizer]

I still have yet to see a LED grow as good as an HID grow. And the LEDs are still waaaay expensive.

Forgive me for not checking those links (don't have the time) but the only LEDs that seemed good enough for cannabis seemed to be needing extensive cooling capabilities. Like a running water jacket. Hardly worthy of consideration if that is the case.

[PauloLx]

Hi there Rand!

Great topic as usual.

Maybe you can help me out.

I intent to use UV lights on my next grow in order to try to replicate the lovelly portuguese sun, i dont stand a chance but you cant blame a man for trying

Anyway i´ve found some cheap UV lamps on the web but i´ve never heard about those...Wood´s lamp???Made out of Wood´s Glass?!

Do you know these ones?Are they any good?

They run at 365nanometers, whatever that means...

Here´s the only mention to it that i could find...

http://en.wikipedia.org/wiki/Wood%27s_lamp

Many thanks