Night and day

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Pompom
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Joined: Mon Dec 11, 2017 7:59 pm
Location: Northern Finland

Night and day

Post by Pompom »

So again I found myself thinking about my plants and plants in general.
I was thinking about differences in plants behaviour when it's day vs. when it's night. What do the plants do at night? When it's day and light available, they do photosynhesis and store energy but what does that mean to the plant? When it's night they breath, but what does that mean to the plant?
When do the plants mostly grow? Is there differences between a normal plant and succulent? In general of course. I'd like to support my plants growth and health as much as possible, so it would be great to know more about their behaviour.

My own subjective experience is that the plants mostly grow at night. I have been growing echeveria from leaves, and they are growing fast and look different every morning. Couple of times I've forgotten to shut the growing light off, and in the morning I see little to none difference in them compared to what they looked like a day before. Is my conclusion right, or just my imagination?

Is there already a discussion about this? If there is, could someone link it here, I find this topic pretty interesting.
Thanks in advance!
(And yes, I tried to google the anwers but got no results in my native language. And scientific articles I found in English have a little too complicated English for me... ](*,) )
DaveW
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Location: Nottingham, England/UK

Re: Night and day

Post by DaveW »

Our plants may even virtually stop growing when conditions get too warm at night in mid summer.

See:-

https://askabiologist.asu.edu/cam-plants

How true and scientifically based this article below is I do not know. It may simply be that in hot climates water evaporates from the ground much quicker when hot during the day, whereas in the cooler conditions at night it takes longer therefore the roots have a longer time to use it. In the UK though and similar cooler climates it is getting the soil to dry out quickly that is the problem, not keeping it wet:-

https://www.desertsun.com/story/life/ho ... /31112227/

I have even heard it said you should not water when the ground is hot as it will turn to steam and kill the roots. I cannot believe this since when it rains in habitat it does not wait until the ground is cool before doing so and many caught in desert rains say the water is freezing cold, but within an hour or so it is evaporating under the blazing hot sun again, so our plants are used to quite a rapid temperature range. Therefore the old gardeners method of placing cans of water in the greenhouse to warm up before watering the plants so not to provide a temperature shock may be unnecessary.
Pompom
Posts: 421
Joined: Mon Dec 11, 2017 7:59 pm
Location: Northern Finland

Re: Night and day

Post by Pompom »

Thanks Dave!
Read the links and also little more about cam from wikipedia. All I can say: Cacti are so interesting plants. I also thought it would be pretty great to keep cacti in bedroom to take carbon dioxide from air as we sleep. Everybody benefits, cacti get carbon dioxide as we breath in closed area and we get little cleaner air. I think.

I also think the steamthing is rubbish. Have you ever dug sand at the beach or in a sandbox? The top sand is superhot but when digging deeper, it gets cooler and cooler. I believe this happens also in deserts. Cacti roots aren't on top inches of the sand aren't they? Also as the top of the sand is super hot in deserts and as the freezing water pours in, the water warms just a little bit on its way deeper to the roots. I've also read about not giving cold water to the cacti, it might be a good advice if the cactus is in a pot and the soil isn't hot. Anyways, cold or warm water, whatever. As long as your plants are healthy and happy, it doesn't matter.

Found this mention from wikipedia: ”Almost all cacti have obligate Crassulacean Acid Metabolism in their stems; the few cacti with leaves may have C3 Metabolism in those leaves; seedlings have C3 Metabolism.” If I understood right, this C3 metabolism is what plants normally do. Now I understand why it's so crusial to keep seedlings in moderated environment. I was wondering if plants grown from cuttings also use C3 metabolism.
DaveW
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Location: Nottingham, England/UK

Re: Night and day

Post by DaveW »

They used to take flowers and plants out of hospital wards in the UK at night because they claimed they breathed out carbon dioxide, not oxygen, but the amount is infinitesimal, so there is probably virtually no difference whether a bedroom has plants in it at night or not. See:-

http://forums.botanicalgarden.ubc.ca/th ... oom.48507/
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TimN
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Location: Phoenix, Arizona USA

Re: Night and day

Post by TimN »

Unless your soil is above 212F/100C water is NOT going to boil, unless maybe if barometric pressure is negative or something. You would have far more urgent problems under those conditions than steamy roots.

I have watered my plants when temps were well over 110F with no observable ill effects.

My understanding of C3 is that at night the plant exchanges CO2 and O2, converting each from/to the chemical storage molecules. Photosynthesis requires sunlight for the plant to take that CO2 and convert it to whatever the plant needs; starch for storage, chemical building blocks for plant parts, etc.

What I can't say for certain is what turns the "growth" activity on an off? Is it dependent on sunlight? It is regulated by temperature? I guess I've always assumed that they grow during the day while the plant is photosynthesizing and generating building blocks.

I'm always cautious about assuming plant activities are dependent on one attribute (temp, photo-period, available water/nutrients, etc).

When winter-dormant plants go dormant is it the temperature or the photo-period? Or something else. Air temp or root/soil temp.

I'll have to dig up my cactus botany book to see if it sheds any light on this.
Disclaimer: I'm in sunny Arizona, so any advice I give may not apply in your circumstances.

Tim
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TimN
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Re: Night and day

Post by TimN »

Where did this come from?

From the DesertSun article. Author states:
"Because gas exchange is active at night, the roots are better able to take up water applied to the soil."

No supporting evidence is presented for this astonishing assertion. What does one have to do with the other?

The article continued to devolve into wild supposition and wishful thinking, in my opinion. I am extremely skeptical that the amount of water taken in by stomata amounts to anything meaningful. I agree with overhead watering to get the benefit of rain simulation to clean the plant off.

I think the pH of the water has more of an effect on a plants ability to take up water.
Disclaimer: I'm in sunny Arizona, so any advice I give may not apply in your circumstances.

Tim
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
Location: Nottingham, England/UK

Re: Night and day

Post by DaveW »

Yes roots being burned off by hot water or steam would probably not be a problem anyway since most cacti are said to loose their hair like fine feeding roots in the dry season in habitat as another method of preventing water loss. The saguaro is said to be able to produce another set of hair like feeding roots within 24 hours of it raining.

The only reference I have read about taking water in from other than roots was cacti with spongy spines like Navajoa's where it was said the spines can absorb water but not seen any scientific evidence for this transferring it into the body.

See:-

https://www.cactiguide.com/forum/viewtopic.php?t=36774

It is more likely cactus spines collect water in rain or foggy and humid situations (Chilean Camachaca fog zone for instance) and let it trickle down the body to the roots.

See:-

https://www.advancedsciencenews.com/lea ... ng-spines/

As to PH of water and plant growth, again it is said cacti grow on limestone because they are slow growing and can, but other more vigorous plants that would crowd them out and overtop them cannot. The claim is they only grow when they receive acid rain and stop growing immediately the limestone bedrock turns it alkaline. Therefore limestone added to potting soil of plants inhabiting limestone in nature acts as a growth retardant for cacti, not a growth promoter, but by slowing down growth keeps them more natural looking and "habitat looking", so not bloated.

See:-

http://ralph.cs.cf.ac.uk/Cacti/Cactus%2 ... linity.pdf
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