Darkness and cacti stomata

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Brunãozinho
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Darkness and cacti stomata

Post by Brunãozinho »

This is just a question out of curiosity and I'm not sure if my deductions are right.

Since cacti open their stomata only at night, I suppose they do this according to their photosensitivity. So, does that mean that the darker it gets, the more the stomata are open? And then, for a cactus that is outside, let's say under a regular city post lamp with a fairly strong light, during the night, would this light influence the stomata being fully open, and thus affecting the cactus "breathing"?
Bruno
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Steve Johnson
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Re: Darkness and cacti stomata

Post by Steve Johnson »

Brunãozinho wrote:This is just a question out of curiosity and I'm not sure if my deductions are right.

Since cacti open their stomata only at night, I suppose they do this according to their photosensitivity. So, does that mean that the darker it gets, the more the stomata are open? And then, for a cactus that is outside, let's say under a regular city post lamp with a fairly strong light, during the night, would this light influence the stomata being fully open, and thus affecting the cactus "breathing"?
The stomata opening only at night is a survival strategy to conserve water in the tissues during the heat of the day. This is common among all xeric plants, not just cacti. Artificial light at night inhibits flowers in night-blooming cacti, but that's the extent of it.
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DaveW
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Re: Darkness and cacti stomata

Post by DaveW »

I think it is mainly a response to temperature differential from day to night in CAM plants, but light evidently plays a part. Some claim cacti virtually stop photosynthesizing when the night time temperature rises above 70F (21C) to avoid water loss so tend to go dormant in the height of the summer, but how true that is I don't know.

http://en.wikipedia.org/wiki/Crassulace ... metabolism" onclick="window.open(this.href);return false;

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1064543/" onclick="window.open(this.href);return false;
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jp29
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Re: Darkness and cacti stomata

Post by jp29 »

Steve Johnson wrote:.......... Artificial light at night inhibits flowers in night-blooming cacti ..........
I am not so sure about that, Steve - I used to believe that to be so. However, the cereoids and Discocactus situated in my front garden are well illuminated by a street lamp but they bloom just as prolifically as my greenhouse plants - and have done so for many years.
James
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https://jp29.org/cactuscult.htm Image
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Steve Johnson
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Re: Darkness and cacti stomata

Post by Steve Johnson »

DaveW wrote:I think it is mainly a response to temperature differential from day to night in CAM plants, but light evidently plays a part. Some claim cacti virtually stop photosynthesizing when the night time temperature rises above 70F (21C) to avoid water loss so tend to go dormant in the height of the summer, but how true that is I don't know.
While my summer heat isn't as extreme compared to the inland areas of SoCal, I have seen my Eriosyce senilis go dormant during the hottest days of August and early September. Aside from that species, summer dormancy isn't something I experience, although our members in the southwest may have a different story to tell.
jp29 wrote:I am not so sure about that, Steve - I used to believe that to be so. However, the cereoids and Discocactus situated in my front garden are well illuminated by a street lamp but they bloom just as prolifically as my greenhouse plants - and have done so for many years.
James, I hope you're right! In the summer of 2012, the city of Los Angeles installed a Sodium vapor lamp on a phone pole right behind my collection. Unbeknownst to me, this is what I came home to one night:

Image

Since I didn't grow any night-blooming cacti back then, the situation didn't bother me. Now that my Discocactus bueneckeri seems to be establishing, I wonder if the orange "barf glow" light spectrum might interfere with the prospect for night blooming. Don't know if the street lights in your area are Sodium vapor, so I'll have to find out what happens. If you are correct, and I can experience night blooming on my Disco -- I'll have my camera at the ready. I normally avoid flash photography for various reasons, although that would be the perfect time for using it since the flash should overwhelm the "barf glow" color for some nice night-time photos. I'm keeping a keen eye out for this prospect! :)
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jp29
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Re: Darkness and cacti stomata

Post by jp29 »

Steve Johnson wrote:.......... James, I hope you're right! In the summer of 2012, the city of Los Angeles installed a Sodium vapor lamp on a phone pole right behind my collection ..........
Well I am at least right for my circumstance - an ordinary old fashioned street lamp with a standard light bulb - but your Sodium vapor lamp might present a problem.
James
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https://jp29.org/cactuscult.htm Image
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Steve Johnson
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Re: Darkness and cacti stomata

Post by Steve Johnson »

jp29 wrote:Well I am at least right for my circumstance - an ordinary old fashioned street lamp with a standard light bulb - but your Sodium vapor lamp might present a problem.
Yeah, that's what I'm afraid of. Once again, we'll just have to find out.
If you just want photos without all the blather, please visit my Flickr gallery.
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hoteidoc
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Re: Darkness and cacti stomata

Post by hoteidoc »

Steve - I'd be looking for a .22 with a silencer on it! Thank god I'm out in the country, cuz those Na lights REALLY drive me crazy! And I DON'T have any lights out @ my place except a 23W CFU backporch light that's only on when I let the cats in!
Once bitten by the cactus collecting/growing bug, there is no known cure!
There's no 12 step programme for Cactaholics...so I shall just have to get some more!!
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cactushobbyman
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Re: Darkness and cacti stomata

Post by cactushobbyman »

hoteidoc wrote:Steve - I'd be looking for a .22 with a silencer on it! Thank god I'm out in the country, cuz those Na lights REALLY drive me crazy! And I DON'T have any lights out @ my place except a 23W CFU backporch light that's only on when I let the cats in!
In my area they'll steal the wire, so it would be just a matter of time before there would be no light. :lol:
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Brunãozinho
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Re: Darkness and cacti stomata

Post by Brunãozinho »

Steve Johnson wrote: the city of Los Angeles installed a Sodium vapor lamp on a phone pole right behind my collection.
My situation is very similar, Steve. Good part of my plants are just under a post with a Sodium vapor lamp. That's why I began asking myself it that would influence the growth of cacti.
Good to read about this experiment. The CAM in the early morning period is influenced by both temperature and light. Here where I live there are massive Opuntia ficus-indica plantations for usage as cattle food. But just a bit to the west (300 km), where the altitude is less than the half of here (here is ~540m and there is ~240m), people don't plant them because they poorly grow there.
They have in overall 30% more rain there, but here night temperatures are lower... There might be many other factors that have influence on this, there are many other cactus that grow there too, but it's curious that O.ficus-indica doesn't develop good there.
Bruno
DaveW
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Re: Darkness and cacti stomata

Post by DaveW »

Hi Steve,

See:-

http://physics.fau.edu/observatory/lightpol-Plants.html" onclick="window.open(this.href);return false;

http://www.ces.ncsu.edu/fletcher/staff/ ... hting.html" onclick="window.open(this.href);return false;
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jp29
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Re: Darkness and cacti stomata

Post by jp29 »

DaveW wrote:..........

http://physics.fau.edu/observatory/lightpol-Plants.html" onclick="window.open(this.href);return false;

http://www.ces.ncsu.edu/fletcher/staff/ ... hting.html" onclick="window.open(this.href);return false;
Thank you for your usual excellent references, Dave -- they give me pause in assessing the possible effects of my adjacent street lamp on my my "night bloomers".
James
My cactus cultivation pages:
https://jp29.org/cactuscult.htm Image
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jp29
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Re: Darkness and cacti stomata

Post by jp29 »

Here is the street lamp which is situated approx. 30 ft across the street from my front garden and that illuminates it at night:

Image

The street lamp at night:

Image

Here are some cacti situated in my front yard in flower at night or early morning (previous night flowers):


Image

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Image

Image

Image

Image

Image

Image
James
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https://jp29.org/cactuscult.htm Image
DaveW
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Re: Darkness and cacti stomata

Post by DaveW »

If they flower like that, street light and all, I would not worry James!
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hoteidoc
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Re: Darkness and cacti stomata

Post by hoteidoc »

Beautiful Melo's, James! I'll take that over "Easter" Lillies. What species? And when you get seeds, can I get in line for some?
Once bitten by the cactus collecting/growing bug, there is no known cure!
There's no 12 step programme for Cactaholics...so I shall just have to get some more!!
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