Determining lighting intensity under fluro tubes for phalaenopsis - Page 3 - Orchid Board

DTEguy · #21 07-26-2012, 02:51 AM

You can download a light meter application if you have a smart phone; the accuracy will depend on your phone and the app but it will give you an idea nonetheless.

"beecam light meter" seems to be pretty accurate when compared to my actual light meter.

I agree with Magnus, all my phals started turning purple from 16 hours of 700 fc from my 4x4 T5 6.5k. No harm tho, just more than enough light.

OzPhal · #22 08-03-2012, 12:11 AM

So I finally received my light meter today and I took some measurements - I was a little shocked by what I found to be honest! I had to move my seedlings closer to the tubes so that now they're about 12cms (~5inches) away from the tubes - that gave me a reading of around 1200fc at approximately the leaf surface.

Picture of the seedlings:

In my nursery area where I'm trying to get some roots to grow on a P. violacea var. 'Blue' and a P. zebrina I have about 900fc at the approximate leaf surfaces - I've also got two flasks there that I will be deflasking next week

Picture of my 'nursery' area:

Do those readings sound ok for what I'm trying to achieve - successful growth? and is that lighting ok for these species:

P. violacea var. 'alba'
P. speciosa var. 'alba'
P. parishii
P. tetraspis 'C1'
P. violacea var. 'blue'
P. cornu-cervi var. 'flava'
P. zebrina
P. coringiana
P. venosa
P. pulchra
P. hieroglyphica
P. fasciata
P. violacea var. 'coerulea'
P. sanderiana
P. sumatrana
P. pantherina
P. javanica var. 'mainshow'
P. cochlearis
P. hyroglyphica
P. speciosa
P. equestris var. ‘ilocos’
P. micholitzii

Thanks for your help and patience

terryros · #23 08-03-2012, 09:17 PM

Be a little careful. The FCC or lumens figures that are usually published for orchids are the peak illumination given the plants in natural lighting situations, usually in greenhouses. The plants get much less during morning and afternoon hours. What the orchids seem to care about in experimental conditions is the total number of photons they receive over the day. Giving 1200 FC for a whole day is a lot of photons. Of course, the spectrum of light you are using matters some and a light meter is not measuring the entire spectrum you are giving.

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naoki · #24 08-04-2012, 02:16 AM

I think when you are comparing the cumulative light intensity over a day between constant artificial light (about 15 hours) and natural light, 1000 fc peak natural light gives similar cumulative light intensity as 500-666fc of constant light. I saw this calculation in one of the articles in AOS website, but I can't find it again.

Additionally usable spectrum for photosynthesis (PAR) is less per footcandle in florescent light than the natural light. According to Table 1 of
http://www.aos.org/Default.aspx?id=230

, useful light of florescent light is about 1/2 of natural light. So 1200fc is about equivalent to the PAR of 1200-1800fc peak natural light. Compared to hybrids, quite a lot Phal species grows better at a higher light once they are well established. Here is useful info:

Cultivation of Palaenopsis

His site has lots of great info about Phal species culture.

But it seems that since your plants may not be well established yet, you should observe closely, and you may need to reduce it a little bit if they look stressed. Especially you should watch out for the "low light" species like P. cochlearis, P. micholitzii, P. tetraspis.

billc · #25 08-04-2012, 03:56 AM

That's a great site Naoki, thanks! Now I know why some of my species languish while some thrive.

Bill

naoki · #26 08-04-2012, 04:19 AM

Quote:

Originally Posted by billc

That's a great site Naoki, thanks! Now I know why some of my species languish while some thrive.

Bill

Yes, I used to specialize on paph species, but I started to do phal species after thoroughly reading his website. There are quite a bit of info (species specific information) still only in Japanese, but you can still see lots of photos for each species if you go to his Jpanaese site. His collection, focusing on regional/populational variations within species, is amazing. He also distributes plants from his breeding/import at super reasonable price. But I don't think we can import them into the US. Unfortunately, I've never seen any US-based nurseries who pay enough attention to natural variations, and breed them in the way to preserve the genetic variation. People in the US breed mutants like albino or aurea, but I'm talking about more subtle variations. I guess it is an unfortunate consequence of AOS judging.

OzPhal · #27 08-04-2012, 10:13 PM

Wow, there's so much to understand about lighting! In theory, to more closely mimic a natural environment I could have one bank of two tubes come on for a few hours then, after that, switch on the other bank so that all four are on. Then do the reverse at 'dusk' but that sounds too complicated haha. It's a shame you can't find that article on the calculation naoki... You don't happen to remember the title do you? So what would you suggest as a continuous fc? I ended up shifting the plants down a little on Friday as I couldn't closely monitor them over the weekend - they're getting around 900fc now continuously. Thanks for all of your input folks...

naoki · #28 08-04-2012, 10:49 PM

I don't think that you'll gain anything by imitating the natural light. Your previous setting (1200fc) or 900fc should be OK. My phal species seedlings (pretty similar to yours) are around 500-900fc range. They are not particularly growing fast, so I would like to get more light, but with my cheap T8 2-bulb shoplight, it is about the limit.

I found the article. It has an unexpected title, so I couldn't find it the other day.

http://www.aos.org/default.aspx?id=516

It's basically calculating the cumulative light by assuming that the natural light intensity changes with semi-circle, parabolic, or Gaussian function. Also it had some data measured from the real sun.