Light requirements of slippers

Very nice photos, Paphioboy! It is difficult to judge the intensity from most photos. There are only 2 photos with EXIF intact, and the first P. volonteanum seems to be pretty dim around 125-200fc, and roths are even dimmer, 60-100fc. The date/time stamp was modified, so I don't know if these photos were taken what time of the day.

Ray's calculater (http://www.firstrays.com/measurelight.htm) seems to be pretty close to my high-end incident light meter (when I use white paper + D300). Since the photos are not using white paper, I added about 1.5 stops to EXIF data.

eggshells said:

My roth, stonei, lowii and philippinense flowered under 400-500 foot candles. All single growths and grew second growths and starters before they flower. 2 flourescent light bulbs with a distance of 18 inches from the apex of the leaves. The lights are on for 8 hours a day.

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That is amazingly small amount of light (even for constant light source). Your setup looks like some light is coming from the window. Do you think that they are getting fair amount of natural light or is the artificial light main source? I'm giving 2-4 times more per day (even for Sigmatopetalum)...

TyroneGenade said:

Paph insigne and parishii are C3 plants, see: http://aob.oxfordjournals.org/content/54/4/583.full.pdf .
A phylogenetic analysis suggests all the Cypripedioideae are C3 (while Catts seem to be mostly CAM): http://www.plantphysiol.org/content/149/4/1838.full

So, because I'm something of an empiricist, if you have a wild location of Paphs near you, spend a day tracking the light intensities that the plants endure. (There are handy gadget that can actually measure photosynthesis i the field but that is perhaps too much to ask...)

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Thanks for the citation, the 2nd one is very interesting. It is amazing how CAM can evolve repeatedly, which tells us how important the interaction between light, water, humidity, and temp. I think there is another paper which checked Brachy (their appearance is closer to CAM), and concluded that they are not CAM, neither.

Yes, field measurement would be great. Portable IRGA (like Li-Cor 6400) is quite expensive (ours are like $20k), though. But I agree that it would be nice if someone can measure PAR or even just lux/fc with a data logger (pretty cheap). I did quick literature search for some field measurements of Paphs, but I haven't found one yet.

For rough estimation of PAR (convert fc to micro mole/m^2/s), here is a couple conversion factors: http://www.apogeeinstruments.com/conversion-ppf-to-foot-candles/
The site says it is PPF, but I think that if you use fc, you get PPFD (photosynthetic photon flux density). micromole = micro E.

TyroneGenade said:

No, LEDs are tricky. You need to know the spectrum of the LED and the bias current. There is a lot of data on LEDs at http://www.apsa.co.za/board/index.php?topic=4454.0. I don't even begin to speculate... What we are finding for the aquariums is that a daylight LED gives just as good growth as weird combinations.

Cool whites and Daylight have almost the same Lux output but the latter have a slightly higher PAR rating so the lower microE estimate is probably closer to the truth.

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I also used to think R+B is better than white LEDs, but it seems that the technology of white LEDs are progressing faster than single color LEDs. So I agree with Tyrone, photosynthesis per consumed electricity of white LEDs seems to be pretty good now. Check Table 1 PPF efficiency column of http://cpl.usu.edu/files/publications/factsheet/pub__4964212.pdf

Additionally, Fig 8A (not the photos) and 7 is pretty interesting:
http://cpl.usu.edu/files/publications/poster/pub__2576523.pdf
In addition to PPF, the spectra influence the shape/size of leaves and photosynthetic efficiency.

naoki said:

That is amazingly small amount of light (even for constant light source). Your setup looks like some light is coming from the window. Do you think that they are getting fair amount of natural light or is the artificial light main source? I'm giving 2-4 times more per day (even for Sigmatopetalum)...

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Nope because my multifloral bench is not even close to a window. Besides all blinds are close all the time and its even bad because I got frost on it every winter. (seals are not very good anymore)

Anyways, I have a photo that you guys might find interesting. Too many to post but this one should summarize it.

I got this philippinense from Ching Hua. Supposed to be the long petalled type. Anyways it has long skinny leaves when I got it. The first picture shows the widest leaves and one of the newest (at that time) it measured 4cm.

Now the second picture shows the new top leaves. They are not as long but its wider. 6-7 cm now. 68cm total leaf span.







So yeah I think its safe to say they got wider.

Those are pretty dark leaves for a phili..