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#1
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light
I go back and forth as to whether its duration or intensity of light tat
makes our plants bloom.. I think the answer is qualified 'yes' but if one was to err I think it would be on intensity rather than duration.. I think plants need a minimum of light but it has to be of a certain intensity. 8 hours of non sufficient light isn't equal to 8 hours of intense light. Or am I nuts,? Has anyone any input on intensity vs duration?\ K Barrett |
#2
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light
Probably a combination of both. For example, P. gigantea needs higher
light levels, and it just won't bloom otherwise, no matter the duration. But getting 3 hours a day of extra strength daylight probably won't give you very happy plants either.... And every species will be different as well. Cheers, Xi |
#3
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light
The quality of flowering is related to the overall health of the plant, but
narrowing the discussion as we have done, I suspect that it's a combination of intensity, duration, and temperature that are key. Photosynthesis is "just" a photochemical reaction, and as such, requires a certain amount of light and a certain temperature to occur optimally. The consumption of the photosynthetically-generated chemical energy (and its storage) are also chemical reactions that are certainly affected by temperature. Respiration - the consumption reaction - goes on pretty much all the time, but increases with increasing temperature. Photosynthesis obviously occurs faster with more light, but I believe there is a "temperature inhibition" thrown in there somewhere. Add to that the fact that a plant used to being grown very bright will have less chlorophyll per unit of surface area. All else being adequate, we are balancing a mass of stores creation and utilization - both rate x duration dependent. So.... longer duration of light at lower levels means a slower generation of energy, and slower respiration and growth. Raise the temperature, and the respiration and growth can outstrip the "building" process of photosynthesis. (There is another reaction that leads to "legginess" in warm, low-light conditions, but let's ignore that one.) High light level increases the rate of generation, but also warms the plant, increasing the respiration rate. Again, maybe to the point of negative returns, especially if the warming impedes the photosynthesis. The shorter duration means less total mass is created. However, if we can keep the plant cool while increasing the light intensity without shortening its duration, you "push" the energy creation and storage more than the consumption, so a "stronger" plant should result. A caveat to that, however, is that some plants don't do well a high light levels. I think I must grow my phals too bright, for example. The best phal blooming I have ever seen was a guy in NJ whose greenhouse was so totally enveloped in algae that you had to wait a minute for your eyes to adjust to the low light levels when coming in from outside. -- Ray Barkalow - First Rays Orchids - www.firstrays.com Plants, Supplies. Books, Artwork, and lots of Free Info! "K Barrett" wrote in message . .. I go back and forth as to whether its duration or intensity of light tat makes our plants bloom.. I think the answer is qualified 'yes' but if one was to err I think it would be on intensity rather than duration.. I think plants need a minimum of light but it has to be of a certain intensity. 8 hours of non sufficient light isn't equal to 8 hours of intense light. Or am I nuts,? Has anyone any input on intensity vs duration?\ K Barrett |
#4
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light
I keep going back to the examples set by the Phal houses in Taiwan, who grow
their plants at high light, high nutrition, and high temps, forcing them, then drop light and temps and the plants flower fantasticly. Or dope growers who keep the growlights on 24/7 never pausing for the so called 'dark reaction' and still their plants bud fantastically. Windowsill growers with a south facing window that gets decent light 6-7-8 hours in a day may or may not get their plants to bloom (let's not talk about lo-e coatings for now.) Sure, like Xi says, its species specific. Some require more light (or as Ray says more food production, utilization and storage) to grow & bloom and some don't. So the windowsill grower selects for plants that grow in his/her conditions. GH growers get a wider range of plant choices, but still, siting can be less than optimal, trees grow, and shady spots occur. Again leading me to wonder is it duration or intensity? If I put a GH on the eastern side of my house where it'll get shaded from about 2PM onwards (nevermind what may occur in winter time when the sun is lower in the sky) would I have better success if I supplement light from 2PM onwards? Or shade less? Or depend on light bounce? To say nothing about the idea that many orchids are from the tropics where the day length is 12 hrs give or take, and there's a surplus of incoming solar radiation. So the person growing in a windowsill in higher latitudes with only 6-7-8 hours of less intense sun... or me thinking about adding a second GH to my property in a less than optimal setting.... Ack! It is a marvel that we can get these things to bloom at all. I'm over thinking. K Barrett "Ray B" wrote in message news:ZKIMj.8649$gT3.4595@trndny02... The quality of flowering is related to the overall health of the plant, but narrowing the discussion as we have done, I suspect that it's a combination of intensity, duration, and temperature that are key. Photosynthesis is "just" a photochemical reaction, and as such, requires a certain amount of light and a certain temperature to occur optimally. The consumption of the photosynthetically-generated chemical energy (and its storage) are also chemical reactions that are certainly affected by temperature. Respiration - the consumption reaction - goes on pretty much all the time, but increases with increasing temperature. Photosynthesis obviously occurs faster with more light, but I believe there is a "temperature inhibition" thrown in there somewhere. Add to that the fact that a plant used to being grown very bright will have less chlorophyll per unit of surface area. All else being adequate, we are balancing a mass of stores creation and utilization - both rate x duration dependent. So.... longer duration of light at lower levels means a slower generation of energy, and slower respiration and growth. Raise the temperature, and the respiration and growth can outstrip the "building" process of photosynthesis. (There is another reaction that leads to "legginess" in warm, low-light conditions, but let's ignore that one.) High light level increases the rate of generation, but also warms the plant, increasing the respiration rate. Again, maybe to the point of negative returns, especially if the warming impedes the photosynthesis. The shorter duration means less total mass is created. However, if we can keep the plant cool while increasing the light intensity without shortening its duration, you "push" the energy creation and storage more than the consumption, so a "stronger" plant should result. A caveat to that, however, is that some plants don't do well a high light levels. I think I must grow my phals too bright, for example. The best phal blooming I have ever seen was a guy in NJ whose greenhouse was so totally enveloped in algae that you had to wait a minute for your eyes to adjust to the low light levels when coming in from outside. -- Ray Barkalow - First Rays Orchids - www.firstrays.com Plants, Supplies. Books, Artwork, and lots of Free Info! "K Barrett" wrote in message . .. I go back and forth as to whether its duration or intensity of light tat makes our plants bloom.. I think the answer is qualified 'yes' but if one was to err I think it would be on intensity rather than duration.. I think plants need a minimum of light but it has to be of a certain intensity. 8 hours of non sufficient light isn't equal to 8 hours of intense light. Or am I nuts,? Has anyone any input on intensity vs duration?\ K Barrett |
#5
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light
I don't think there is a simple answer to your question since orchids
are so different in their natural lighting environments and probably adapt over time to changes in the environment. If we could only see them in their natural habitat that would give us some clues as to what ideal conditions are. On Apr 13, 11:01*pm, K Barrett wrote: I go back and forth as to whether its duration or intensity of light tat makes our plants bloom.. I think the answer is *qualified 'yes' but if one was to err I think it would be on intensity rather than duration.. I think plants need a minimum of light but it has to be of a certain intensity. *8 hours of non sufficient light isn't equal to 8 hours of intense light. Or am I nuts,? Has anyone any input on intensity vs duration?\ K Barrett |
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