About two months ago Sput left home to begin his journey through engineering school. Soon thereafter, when sanitizing his room, I (a.k.a. dad) found a bag with a number of pot seeds. Thinking it would be fun to see them sprout I germinated them and then of course, they sprouted, so I had to transplant them (in various ways) and… so began the first grow. That was the origin of our grow fever but, it didn’t end there. Sputnick decided this would be a good way for us to keep in touch and have some fun at the same time (scientists and engineers do have some strange ideas about fun). Both our schedules are cramped so this is going to take some quite a bit of effort to complete. Wish us luck!
This (with the administrators’ permission of course) will be the means of communicating our research and design ideas between us and with the greater grow community. If you have any suggestions, directions, links, experiences, whatever you would like, please take the time to post.
And so, I started with a paper by Tazawa that Ozgrowa cited. After re-reading it I believe that it is an excellent reference although there are unexplained assumptions and biases, errors, omissions, and perhaps transliteration problems within the text and tables. Here are some of my initial conclusions and recommendations:
http://ss.jircas.affrc.go.jp/engpage...wa/tazawa1.htm http://ss.jircas.affrc.go.jp/engpage...a2/tazawa2.htm
A) The paper was written with commercial interests (costs) foremost. Because our project is for fun, not-for-profit, I suggest we ignore power consumption à photo conversion efficiencies unless there are other significant reasons to reevaluate (e.g. excess heat production).
B) A key aspect of the lighting is the PPFD (photosynthetic photon flux density, conv. 16.8 umol/m-m-s-klux for daylight). Color rendition HPS and grow-Flo’s produce more PPFD’s/lux than sunlight because UV, green, and IR are not PAR. Other lamps can be used (if desired) for better color balance. Forget the quantum sensor, we ain’t got one.
C) Plants adapt to total PPFD by producing more or less chlorophyll, within the same plant.
D) Different morphological changes occur as a result of the ratio of blue/red and red/far-red light. Depending on species, the color and duration of light exposure can affect flower formation.
E) There is a saturation point at which greater PPFD no longer increases the rate of photosynthesis. The saturation point varies widely between species. WE MUST HAVE AN ESTIMATE FOR MJ.
F) “Composite Lighting” part 1 - fig 10 looks really good but isn’t explained. WHAT IS IT?
G) Part 2 fig 1, what is “CIE photopic curve”, maybe sensitivity of human eye?
H) Defines “light quality” as closeness of agreement of source R/B ratio to photosynthesis action spectum (PAS). For lack of any other justification, I agree and will assume it implies growth (mass) rate. Error: optimum R/B for PAS is 1.9 not 2.71. Doesn’t describe “effective” growth.
I) MH is only lamp that solo can produce good quality growth (ed. without stretching).
J) The title and contents of Part 2 table 6 don’t agree with each other or text.
K) HPSL…lead to optimum conditions for growth (ed. growth here means increase in height).
L) The mean PAS matches very closely the absorption spectrum of chlorophyll (duh).
Based on this data we should be able to configure the chamber with a set of light sources that blend to produce the appropriate spectral balance (PAS) and flux PPFD.