splifchris
Well-Known Member
The existence of nearly all life on earth is fuelled by light from the sun. Plants are no exception. They use the energy of sunlight to turn air into simple sugars a process known as photosynthesis. These sugars are the building blocks which allow plants to grow. Light can be thought of as the motor of photosynthesis. Plants need light to grow and bloom they absorb light primarily using the pigment chlorophyll, which is the reason that most plants have a green colour. Photosynthesis occurs when green leaves catch light and transform it, using water as a fuel, into chemical energy. This energy is preserved as matter (sugar composed from carbon dioxide).
When it gets dark, photosynthesis stops. The plant closes its pores as much as possible and the stream of water inside the stem slows down and almost comes to a stop. When light returns, the first pores open to admit carbon dioxide and pass a sort of perspiration water. Carbon dioxide is the raw material for sugar the final product of photosynthesis. Through this process of evaporation the juice stream, beginning at the roots, commences once again.
In nature, light comes from the sun. The sun radiates the whole spectrum of light, some of which is invisible to the human eye. We can however feel and detect the influences of the non-visible radiation. We feel infrared as heat and experience the effects of sunburn and pigments of UV-light. Plants, on the other hand, are completely adapted to sunlight. A plant mainly uses the light elements of the visible spectrum from blue to red.
Over the last thirty years a lot of research has been undertaken into the light requirements of plants. We know that plants need light outside the visible spectrum the light we cannot see. Whilst some reactions to light have been accurately described and certain photo-active matters have been discovered, the secret of light remains a mystery. Assimilation bulbs (such as the Philips Son-T Plus) used for growing plants try to emulate the sun as accurately as possible.
Light influences plants in the following ways:
Light moves in waves and the distance between the two highest peaks is known as the wavelength. Each colour we see has a specific wavelength. When the waves change, such as when they are reflected, the colour of the light also changes. The wavelength is measured in nanometres (nm). One metre is the same as 1.000.000.000 (one billion) nanometres, i.e. one nanometre is a billionth of a metre!
The visible range of light is from blue to red. Visible blue light has a wavelength of 400 nanometres. Visible red light has a wavelength of more than 700 nanometres. Blue light is comprised of more waves than red light over the same distance so it moves more often and with greater speed. Consequently, blue light has more energy than red light.
Beyond blue light is ultraviolet light (UV) this has even more energy! Further along the spectrum are roentgen and gamma radiation. And, at the other end of the spectrum, red is followed by infrared (IR) and long-wave radio radiation.
In spite of photosynthesis only taking place with light from the visible spectrum, scientists have discovered that plants which receive only light of 400-700 nanometres succumb to more diseases. They also found that these plants did not grow and bloom as successfully, even when the amount of Watts was increased. We know that plants need both the blue and red parts of the light spectrum. When a plant is growing in the vegetative stage (especially a mother plant) it requires extra blue light. Extra red light stimulates blooming plants insofar as they bloom more often and have a greater number of larger flowers.
Blue parts of light will cause plants to become thick and stout. Light with a lot of blue parts is ideal for mother plants because the plants remain squat and produce a lot of side branches. These form ideal stock for healthy, quick-growing cuttings. Metal halide bulbs produce light with more blue parts.
Light streams, lumens and lux
Just as important as the structure of light is the light flux or luminosity. The luminosity (measured in lumens) of a bulb depends on its electric power (measured in Watts). The specification of assimilation bulbs often refers to lumens (=lm). A bulb of 400 Watts can produce between 30,000 and 60,000 lumens, and 600 Watt bulbs about 90,000 or more.
The luminosity that shines on one square meter is measured in Lux.
Examples of values in Lux include:
Cloudless day: 100,000 Lux
Closed grey layer of clouds: 10,000 18,000 Lux
Well-illuminated living room: 500 Lux
Candle at a distance of one metre: 1 Lux
Night full moon: 0.25 Lux
A bulbs luminosity not only depends on its capacity (i.e. the number of Watts) but also on the distance of the measurement point from the light source. The luminosity decreases if this distance is increased. A young plant that receives too little light will become long and skinny and the distances between the side branches (also known as the internodal length) will increase. In nature a plant only knows the light of the sun. If there is not enough light the plants survival mechanism kicks in and it tries to outgrow whatever is shading it. The plant concentrates on becoming taller in order to access more light. Of course, this vertical growth spurt requires a great deal of energy and if the light conditions dont improve the plant will begin to die. Leggier plants also require more energy to transport water. A plant that has grown under good light conditions has much more energy, disease resistance, and greater health.
Its amazing (not to mention useful) to note that the brightness of your lights can determine the height of your plants. A lot of light means small and thick-set plants. Less light means long and thin plants. The quality of the light (i.e. the presence of all light colours) is the key factor of good photosynthesis.
Some plants need a full twelve hours darkness in order to ensure abundant and full flowering heads particularly during the first twelve days of the blooming period. So its essential that these plants are left undisturbed.
Light and the direction of growth.
Light determines the growing direction of your plants. If the light comes from the right or the left and not from above, your plants will grow in this direction. However when there is an abundance of light plants dispose of measuring constructions that is, they no longer compare the incidence of light on a part of the leaf to the other parts of the leaves.
Light gives information to the growth tips of plants. Blue light provides the impulse for the direction of growth because it is energy rich and has a short wavelength. Amazingly, this gives blue light the possibility to penetrate the substrate and provides the roots with information about the direction of growth too!
Thinking back to your school-days you may remember a certain experiment involving a potato. (But then again, which experiment you remember depends on what sort of school you went to!) A potato is put in a light-proof box and separated from the external world by two dividing walls. A hole is made in each wall and after a while the white sprout of the potato grows right up to the light, in spite of the fact that it was dark inside the box. When the white sprout reaches the light, the parts of the plant turn green and photosynthesis starts. The whole growth is not operated by photosynthesis alone but by another organ of the plant that is able to detect a few photons (light parts) and react. The potato has so much energy (starch = sugars), that it is able to take a meandering route through the box to reach the light.
Growing points (like the first point of the sprout) have an eye for light flashes that we cannot see. Seedlings in the ground find their way to the light world in the same way.
Light the bloom trigger
All blooming plants can be divided into three groups:
Indoor growers know that switching their lights on for eighteen hours or more keeps their plants in a vegetative (rather than flowering) state. Under these conditions, the plant only produces leaves and stems, but no flowers. When the plant receives twelve hours darkness it begins to make blooming tissue in its axils. These little blooming points are called embryonic tissue. This early flowering period is more sensitive to interruptions of light than later on in the blooming period. It only takes a few days from switching the light on until the production of the first (embryonic) blooming tissue. A mistake in this crucial first twelve days can ruin a harvest.
Interruptions in the daytime, like a power failure or bulbs that break, are not as disastrous. The plants will stop developing and the bloom will be later, but the biological clock will not be disturbed.
Interruptions of the night, on the other hand, can be disastrous. These interruptions can be very short but they will have huge consequences depending on the colour of the light. When the plant is disturbed at night with a light red colour it takes only a minute to confuse the plant and turns off the plants switch to bloom. Research has found that disturbances in the middle of the night, say after six hours of darkness, have the worst consequences. Even the light that shines under a door can be damaging. If the plants get no rest at night, they will not flower properly, or worse still, not flower at all. Later on in the blooming period, when the flowers have developed, a disturbed nights rest will affect the crop, but the plants will keep blooming. This is because the transformation from growth to bloom has already been successfully achieved.
Outdoors, plants that have a full moon at the beginning of the blooming period need a lot more time to develop the blooming points than plants that commence the same process during dark, moonless nights.
Home growers claim that for these types of plants the best light conditions are a period of ten hours of light and fourteen hours of darkness. However, in spite of this many growers of resin-producing plants prefer an even split of 12/12. With twelve hours of light we double the amount of resin production than if we use ten hours of light.
Found on urbangarden.com... thought id share > Chris
When it gets dark, photosynthesis stops. The plant closes its pores as much as possible and the stream of water inside the stem slows down and almost comes to a stop. When light returns, the first pores open to admit carbon dioxide and pass a sort of perspiration water. Carbon dioxide is the raw material for sugar the final product of photosynthesis. Through this process of evaporation the juice stream, beginning at the roots, commences once again.
In nature, light comes from the sun. The sun radiates the whole spectrum of light, some of which is invisible to the human eye. We can however feel and detect the influences of the non-visible radiation. We feel infrared as heat and experience the effects of sunburn and pigments of UV-light. Plants, on the other hand, are completely adapted to sunlight. A plant mainly uses the light elements of the visible spectrum from blue to red.
Light influences plants in the following ways:
- The direction of incoming light determines the direction of the plants growth.
- The composition of light (the spectrum) influences the metabolism.
- The intensity of light determines the height of the plant.
- The duration and order of the light periods can trigger a new life-cycle (e.g. grow / bloom).
Light moves in waves and the distance between the two highest peaks is known as the wavelength. Each colour we see has a specific wavelength. When the waves change, such as when they are reflected, the colour of the light also changes. The wavelength is measured in nanometres (nm). One metre is the same as 1.000.000.000 (one billion) nanometres, i.e. one nanometre is a billionth of a metre!
The visible range of light is from blue to red. Visible blue light has a wavelength of 400 nanometres. Visible red light has a wavelength of more than 700 nanometres. Blue light is comprised of more waves than red light over the same distance so it moves more often and with greater speed. Consequently, blue light has more energy than red light.
In spite of photosynthesis only taking place with light from the visible spectrum, scientists have discovered that plants which receive only light of 400-700 nanometres succumb to more diseases. They also found that these plants did not grow and bloom as successfully, even when the amount of Watts was increased. We know that plants need both the blue and red parts of the light spectrum. When a plant is growing in the vegetative stage (especially a mother plant) it requires extra blue light. Extra red light stimulates blooming plants insofar as they bloom more often and have a greater number of larger flowers.
Blue parts of light will cause plants to become thick and stout. Light with a lot of blue parts is ideal for mother plants because the plants remain squat and produce a lot of side branches. These form ideal stock for healthy, quick-growing cuttings. Metal halide bulbs produce light with more blue parts.
Light streams, lumens and lux
Just as important as the structure of light is the light flux or luminosity. The luminosity (measured in lumens) of a bulb depends on its electric power (measured in Watts). The specification of assimilation bulbs often refers to lumens (=lm). A bulb of 400 Watts can produce between 30,000 and 60,000 lumens, and 600 Watt bulbs about 90,000 or more.
The luminosity that shines on one square meter is measured in Lux.
Examples of values in Lux include:
Cloudless day: 100,000 Lux
Closed grey layer of clouds: 10,000 18,000 Lux
Well-illuminated living room: 500 Lux
Candle at a distance of one metre: 1 Lux
Night full moon: 0.25 Lux
Its amazing (not to mention useful) to note that the brightness of your lights can determine the height of your plants. A lot of light means small and thick-set plants. Less light means long and thin plants. The quality of the light (i.e. the presence of all light colours) is the key factor of good photosynthesis.
Some plants need a full twelve hours darkness in order to ensure abundant and full flowering heads particularly during the first twelve days of the blooming period. So its essential that these plants are left undisturbed.
Light and the direction of growth.
Light determines the growing direction of your plants. If the light comes from the right or the left and not from above, your plants will grow in this direction. However when there is an abundance of light plants dispose of measuring constructions that is, they no longer compare the incidence of light on a part of the leaf to the other parts of the leaves.
Light gives information to the growth tips of plants. Blue light provides the impulse for the direction of growth because it is energy rich and has a short wavelength. Amazingly, this gives blue light the possibility to penetrate the substrate and provides the roots with information about the direction of growth too!
Thinking back to your school-days you may remember a certain experiment involving a potato. (But then again, which experiment you remember depends on what sort of school you went to!) A potato is put in a light-proof box and separated from the external world by two dividing walls. A hole is made in each wall and after a while the white sprout of the potato grows right up to the light, in spite of the fact that it was dark inside the box. When the white sprout reaches the light, the parts of the plant turn green and photosynthesis starts. The whole growth is not operated by photosynthesis alone but by another organ of the plant that is able to detect a few photons (light parts) and react. The potato has so much energy (starch = sugars), that it is able to take a meandering route through the box to reach the light.
Growing points (like the first point of the sprout) have an eye for light flashes that we cannot see. Seedlings in the ground find their way to the light world in the same way.
Light the bloom trigger
All blooming plants can be divided into three groups:
- The first group contains plants that start to bloom independently of the length of the day and the night.
- The second group contains plants that start to bloom as a certain length of day is exceeded, i.e. when there are long days and short nights.
- The third group contains plants that start to bloom if a certain length of night is exceeded.
Indoor growers know that switching their lights on for eighteen hours or more keeps their plants in a vegetative (rather than flowering) state. Under these conditions, the plant only produces leaves and stems, but no flowers. When the plant receives twelve hours darkness it begins to make blooming tissue in its axils. These little blooming points are called embryonic tissue. This early flowering period is more sensitive to interruptions of light than later on in the blooming period. It only takes a few days from switching the light on until the production of the first (embryonic) blooming tissue. A mistake in this crucial first twelve days can ruin a harvest.
Interruptions in the daytime, like a power failure or bulbs that break, are not as disastrous. The plants will stop developing and the bloom will be later, but the biological clock will not be disturbed.
Interruptions of the night, on the other hand, can be disastrous. These interruptions can be very short but they will have huge consequences depending on the colour of the light. When the plant is disturbed at night with a light red colour it takes only a minute to confuse the plant and turns off the plants switch to bloom. Research has found that disturbances in the middle of the night, say after six hours of darkness, have the worst consequences. Even the light that shines under a door can be damaging. If the plants get no rest at night, they will not flower properly, or worse still, not flower at all. Later on in the blooming period, when the flowers have developed, a disturbed nights rest will affect the crop, but the plants will keep blooming. This is because the transformation from growth to bloom has already been successfully achieved.
Outdoors, plants that have a full moon at the beginning of the blooming period need a lot more time to develop the blooming points than plants that commence the same process during dark, moonless nights.
Home growers claim that for these types of plants the best light conditions are a period of ten hours of light and fourteen hours of darkness. However, in spite of this many growers of resin-producing plants prefer an even split of 12/12. With twelve hours of light we double the amount of resin production than if we use ten hours of light.
Found on urbangarden.com... thought id share > Chris
