dr-green-thumb
Well-Known Member
Lights & Plants
Plant growth, harvest, potency and even the time to flower are all dependent on the light they receive. Light quality, intensity and duration are all important. The following is a brief introduction to plants, light, lumens and PAR.
Light is a plants food, nutrients are only building blocks for the plant cells but it is light that provides the energy ~ so how does it work?
When light falls onto leaves it triggers the process of photosynthesis, which in simple terms is the process of turning light, which is radiant energy, into chemical energy. The amazing process of photosynthesis, turning light energy into chemical energy, is one of natures wonders. This energy transfer happens inside the plants cell structures called chloroplasts. The basic components of chloroplasts are individual membranous sacs, which contain fats, proteins and pigments (stay with us ~ it's worth knowing!)
Pigments & Chemical Energy
Pigments play an important part. They absorb light in the photosynthesis process of turning light energy into chemical energy. Chlorophyll, for example, is an important pigment, which absorbs red and blue wavelengths. There are different types of pigment and each absorbs different wavelengths of light. The light absorbed by the pigment causes a reaction, which produces chemical energy (it makes electrons out of the light, and the electrons use their charges to make sugar energy for the plant)
For those interested in the current theory of photosynthesis, it works something like this ~
The chemical energy produced by the chlorophyll (pigment) from light is sufficient to split the water molecules apart. This provides units of hydrogen (H) and hydroxide (OH). The hydroxide combines with carbon dioxide, which is absorbed from the air, to produce carbohydrates, which provides the energy for plant growth. (and you thought there was nothing going on in your plants ~ for more details visit your library!)
So to summarise ~ light falls on the leaves which convert it into electrons and the plant uses these electrons (electricity) to make energy as sugar.
Light & Light Measurement
Light, its intensity, quality, its colour, spectrum, wavelength are therefore all-important factors, but how do we measure light and what are the most important components?
Light is measured in photons (which we, or at least I, do not really understand). Light actually hits objects, just like a spray of water, and the sun emits lots of light photons ~ to give you an idea of how many; the sun hits our body with over 12,000,000,000,000,000,000,000,000 photons every second and a plant needs about 20 photons to make a finished molecule of sugar.
So our scientists can count the number of photons hitting the plant and even predict how much of this energy will convert into flowers or fruits. Each industry has its own way of measuring light. Photographers use a light meter, the lighting industry uses lumens or lux and the gardening industry uses PAR. All are only measurements; the actual light coming from a lamp or the sun does not change ~ only the methods we use to measure are different. Light Spectrums & Colours
Light from the sun is ideal but it's not the same as artificial light, where output quality, spectrum etc varies upon the type of lamp and how it is used. Many growers think that more lumens = better growth / yields, when in fact artificial light, even at its best in a HID or HPS lamp in not so good in terms of colours. Much of the light from the bulb is not used by the plant, mainly because it is not in the 400 to 700 nw (nanawave) spectrum, and plants can only see and use light in this range. Light quality and its colours are as important as lumens. < /FONT >
Light, as seen by plants, is not a single colour but separate bands of active colours and the plant senses each colour-band of light as a separate signal. Each band of colour has a different effect on plants and the following are only a few of the functions, which each band of light promotes.
Blue Light (350 - 500 NW) powers chlorophyll production, powers cell actively, energies the stomata movement and makes the plant follow light.
Green / Yellow Light (500 - 650 nw) ~ not much action from these bands of light.
Red Light (600 - 700 NW) makes sugar from CO2, powers chloroplast production, signals light and dark times among other functions.
Strong blue and red light photons (as above) are also needed for good carbon dioxide uptake.
The PAR scale measures all these coloured photons between 400nw & 700nw, the critical range for plants, as this is only range that plants can use light. If it is not in this range then it's wasted light.
Plant growth, harvest, potency and even the time to flower are all dependent on the light they receive. Light quality, intensity and duration are all important. The following is a brief introduction to plants, light, lumens and PAR.
Light is a plants food, nutrients are only building blocks for the plant cells but it is light that provides the energy ~ so how does it work?
When light falls onto leaves it triggers the process of photosynthesis, which in simple terms is the process of turning light, which is radiant energy, into chemical energy. The amazing process of photosynthesis, turning light energy into chemical energy, is one of natures wonders. This energy transfer happens inside the plants cell structures called chloroplasts. The basic components of chloroplasts are individual membranous sacs, which contain fats, proteins and pigments (stay with us ~ it's worth knowing!)
Pigments & Chemical Energy
Pigments play an important part. They absorb light in the photosynthesis process of turning light energy into chemical energy. Chlorophyll, for example, is an important pigment, which absorbs red and blue wavelengths. There are different types of pigment and each absorbs different wavelengths of light. The light absorbed by the pigment causes a reaction, which produces chemical energy (it makes electrons out of the light, and the electrons use their charges to make sugar energy for the plant)
For those interested in the current theory of photosynthesis, it works something like this ~
The chemical energy produced by the chlorophyll (pigment) from light is sufficient to split the water molecules apart. This provides units of hydrogen (H) and hydroxide (OH). The hydroxide combines with carbon dioxide, which is absorbed from the air, to produce carbohydrates, which provides the energy for plant growth. (and you thought there was nothing going on in your plants ~ for more details visit your library!)
So to summarise ~ light falls on the leaves which convert it into electrons and the plant uses these electrons (electricity) to make energy as sugar.
Light & Light Measurement
Light, its intensity, quality, its colour, spectrum, wavelength are therefore all-important factors, but how do we measure light and what are the most important components?
Light is measured in photons (which we, or at least I, do not really understand). Light actually hits objects, just like a spray of water, and the sun emits lots of light photons ~ to give you an idea of how many; the sun hits our body with over 12,000,000,000,000,000,000,000,000 photons every second and a plant needs about 20 photons to make a finished molecule of sugar.
So our scientists can count the number of photons hitting the plant and even predict how much of this energy will convert into flowers or fruits. Each industry has its own way of measuring light. Photographers use a light meter, the lighting industry uses lumens or lux and the gardening industry uses PAR. All are only measurements; the actual light coming from a lamp or the sun does not change ~ only the methods we use to measure are different. Light Spectrums & Colours
Light from the sun is ideal but it's not the same as artificial light, where output quality, spectrum etc varies upon the type of lamp and how it is used. Many growers think that more lumens = better growth / yields, when in fact artificial light, even at its best in a HID or HPS lamp in not so good in terms of colours. Much of the light from the bulb is not used by the plant, mainly because it is not in the 400 to 700 nw (nanawave) spectrum, and plants can only see and use light in this range. Light quality and its colours are as important as lumens. < /FONT >
Light, as seen by plants, is not a single colour but separate bands of active colours and the plant senses each colour-band of light as a separate signal. Each band of colour has a different effect on plants and the following are only a few of the functions, which each band of light promotes.
Blue Light (350 - 500 NW) powers chlorophyll production, powers cell actively, energies the stomata movement and makes the plant follow light.
Green / Yellow Light (500 - 650 nw) ~ not much action from these bands of light.
Red Light (600 - 700 NW) makes sugar from CO2, powers chloroplast production, signals light and dark times among other functions.
Strong blue and red light photons (as above) are also needed for good carbon dioxide uptake.
The PAR scale measures all these coloured photons between 400nw & 700nw, the critical range for plants, as this is only range that plants can use light. If it is not in this range then it's wasted light.
