Below is response to a question i asked over on IC. It seems to validate my hypothesis regarding broad light spectrums, and possibly why high lumens per SINGLE watt is not THAT important. Anybody with a clue, please feel free to chime in. Oh, there are several color charts on IC that did not transfer
TranceAddictT7: I apologize for the great delay. I am on a schedule that rarely allows any free time so please bear with me as I update this thread.
I'm glad this information was useful to those that showed their appreciation.
Quote:
Originally Posted by PetFlora View Post
So, at the end of the day is the 64,000 question
What is the optimum amount of watts of each corresponding light spectrum needed to optimize chlorophyll A & B production?
Don't quote me, but I would imagine the broader the spectrum of light the greater the easier it will be to provide the full range of wavelengths that a plant can use. In order to know which ones are absorbed most effectively one would have to isolate the chloroplast pigments from a specific strain and run them through a spectrophotmeter to measure the absorbance at different wavelengths. I tend to imagine that the results would vary slightly by strain.
It would actually be interesting to know which wavelengths cannabis plants (generally) absorb light at the most efficiently. We can then look at those light bulb boxes and see if they really are the best fit for our plants or not.
While we're on the topic here is an interesting article on how plants cope with "too much light" to avoid photodamage. Some of the things discussed here are mentioned.
http://www.plantphysiol.org/content/125/1/29 .
Back to the discussion at hand...
We now know that light is the energy behind creating ATP and NADPH and that there are two photosystems in the thylakoid membranes of chloroplasts responsible for utilizing this energy. Let us now break down linear electron flow into steps to be able to see what happens to that excited electron after a photon of light strikes a pigment molecule at a light harvesting complex of PS II.
1. As the electron returns back to its ground state, an electron in a nearby pigment molecule is simultaneously raised to an excited state. This process continues as the energy is "bounced" around until it reaches the P680 pair of chlorophyll a molecules in the PS II reaction-center complex. At this point, it excites an electron within the complex to a higher energy state.
2. The electron is then transferred from the excited P680 to the primary electron acceptor. We refer to the P680 as P680+, attributing a "+" sign to indicate the transferred negatively charged electron.
3. Next, an enzyme catalyzes (speeds up) the splitting of a water molecule into two electrons, two hydrogen ions (H+), and an oxygen atom. The electrons replace the ones that were transferred or lost to the primary electron acceptor from the two P680+ pairs. Due to the nature of the P680+ molecule, this replacement of electrons happens extremely quickly. (P680+ is one of the strongest biological oxidizing agents known to date.) The remaining H+ ions from water are released into the thylakoid space. The oxygen atom combines with a second oxygen atom generated by the splitting of another water molecule, forming oxygen in its diatomic state (O2). Now you know exactly how and where our beloved oxygen that plants produce comes from and why they depend on water.
4. Every transferred electron passes from the primary electron acceptor of PS II to PS I via an electron transport chain. The electron transport chain between PS II and PS I contains: the electron carrier known as plastiquinone (Pq), a cytochrome complex, and a protein called plastocyanin (Pc).
5. The fall of electrons to a lower energy level is what provides energy for the synthesis of ATP. As the electrons pass through the cytochrome complex, H+ ions are pumped into the thylakoid lumen, creating a proton gradient that is used in chemiosmosis. Remember that the H+ ion is a proton, and chemiosmosis is the diffusion of ions across a selectively permeable membrane.
6. As the light energy is transferred via the light harvesting complex pigments to the PSI reaction-center complex, an electron from each of the P700 pair of chlorophyll a molecules becomes excited. The photoexcited electron is again transferred in a similar manner as before to PS I's primary electron acceptor, making the two molecules P700+. Each P700+ is now without an electron and would certainly like to get it back. The electrons that will replace the ones it passed on to its primary electron acceptor will again be passed on from PS II as this cycle repeats itself.
7. The photoexcited electrons with the primary electron acceptor of PS I are passed in a series of redox reactions down a second electron transport chain through the protein ferredoxin (Fd). This chain does not produce a proton gradient and therefore does not produce ATP.
8. Finally, the enzyme NADP+ reductase catalyzes the transfer of electrons from Fd to NADP+. Two electrons are used to reduce NADP+ back to NADPH. This restored molecule has a higher energy state than water and can provide the electrons necessary for the reactions of the Calvin cycle. In essence, the whole scheme is one big recycling system!
Here is a diagram to help demonstrate the steps above:
This image has been resized. Click this bar to view the full image. The original image is sized 1050x580.
Here is a picture with a proton "pump" included so you can get an idea on how it functions:
This image has been resized. Click this bar to view the full image. The original image is sized 1278x751.
And to help you understand chemiosmosis better keep in mind that things will naturally go from higher concentrations to lower concentrations. This isn't the only place where H+ flows down a gradient to generate energy. Many different cells use this phenomenon in many places to synthesize ATP. Read this short and easy to comprehend article about the types of diffusion that exist:
http://antranik.org/movement-of-subs...ell-membranes/
The next post will briefly describe cyclic electron flow which is an alternative way that light is used in these reactions. I will then break down the Calvin cycle. Lastly, we will look at the basics of C3, C4, and CAM plants, how they differ and why it matters. My goal is for the people who read this to have a basic and proper understanding of plants and (hopefully) be able to obtain a greater appreciation for them. Please stay tuned, as always. Thanks
I probably left a good ounce unaccounted for
