Photosynthesis stops after 17 hours? Lost study.

[Nio]

There was a study done recently which found out that after 17 hours of light exposure, utilization on carbon dioxide and photosynthesis stops in cannabis. Unfortunately I can no longer find this study. I think it was up on pubmed but I am a little unsure of that too. So I thought I'd ask here if anyone has also read this study? 'Cause I need to find it so I can actually mention this piece of information to anyone. I mean it's ground breaking work, it finally settles it; that there's no point running your light for 24-hours when photosynthesis stops at 17-hours.

You can't imagine how many search words, phrases on quotations and combinations of word I have tried on google so far.

 

[Zill]

Nio,

I grow outside.

But, given the plants photoperiod does anyone actually expose the plant to light for 24 hrs?

 

[hilbert]

But, given the plants photoperiod does anyone actually expose the plant to light for 24 hrs?

Some people veg with 24 hour lights on. I don't cause I feel like the plants need a little sleepy time but there are those that do.

 

[Zill]

Hey hilbert,

Yup, I just read that. Couldn’t find the article. Photosynthesis raging for 17 hours - you can imagine that things like water may become somewhat limiting and cause the stomata to close. That will shut down photosynthesis and help manage photorespiration.

 

[LoveGrowingIt]

This has been an interest of mine ever since I learned that some growers run lights 24/0. They claim it's worth doing, but I've always doubted that that's true. I suspect at some point extending light duration may be a waste of electricity. I wonder, however, if perhaps the natural adaptation for dark periods is being bred out.

Copilot, Microsoft's AI assistant, says cannabis needs darkness "to convert environmental carbon dioxide into glucose and other simple sugars." It cited three articles:

• https://www.royalqueenseeds.com/blog-the-importance-of-the-dark-cycle-in-cannabis-cultivation-n906
• https://www.cannaconnection.com/blog/18718-importance-of-darkness-for-plants
• https://www.americover.com/darkness-important-cannabis-plants/

 

[Zill]

LG,

Be careful. In plant physiology photosynthesis has light and dark reactions. I think they may be referring the these dark reactions as not being dependent on captured light energy.

 

[LoveGrowingIt]

Be careful. In plant physiology photosynthesis has light and dark reactions. I think they may be referring the these dark reactions as not being dependent on captured light energy.

Okay. I haven't explored this subject in depth. I mostly just consider it when it arises in conversation. I'm just naturally curious and this is an interesting topic. Nevertheless, I run my lights 18/6 for vegetation and 12/12 for flowering and I don't foresee any reason to change.

In addition to plant physiology, I sometimes question the practicality of 24/0 lighting regarding return-on-investment. That is, I wonder how much is gained or lost during those additional six hours of lighting. So far, nothing has convinced me there's any good reason to change to longer duration lighting.

 

[Zill]

All good LG! I always put myself in the plants situation. I doubt any plant has developed certain characteristics due to the sun being there 24/7.

 

[cannafarmer420]

All good LG! I always put myself in the plants situation. I doubt any plant has developed certain characteristics due to the sun being there 24/7.

I am with Zill,
There are processes that are done primarily at night in plants, obviously they seem to be able to adapt to 24 hrs and survive, but its not natural. I try to be kind to my plants and let them sleep✌

 

[Trash_2002]

Cannabis dosen't need rest time in veg, BUT
Running veg at 18/6 is beneficial, they like a rest time and will also cut veg power bills costs by 25%, win-win
for cloning 24/7 lights on will help maintain a good stable temperature trough the nights and days.

 

[LoveGrowingIt]

All good LG! I always put myself in the plants situation. I doubt any plant has developed certain characteristics due to the sun being there 24/7.

I think that way, too. In other words, our job as growers is to figure out what the plants need and then give it to them. It's simple, really.

 

[LoveGrowingIt]

From the little reading I've done, it isn't apparent that they sleep or rest at night. Instead, they change what they do, particularly regarding sugar production and use. Also, photosynthesis ceases, while respiration continues and requires energy. During the day, they produce more sugar than they need and store it as starch. They then use it at night when they need energy for respiration. This system prevents sugar supplies and energy from excessive fluctuation. So, I wonder what effect there might be when there is no dark period to consume the excess sugar supplies. Could the excess become toxic, or could it enhance growth?

 

[Zill]

LG,

Plants love to store excess carbos. Look inside cells near the chloroplasts. Those sharp angled crystals are starch.

I’ll do a quick search for your ask.

Z.

 

[7munkee]

I'm sure there is a limit to the DLI a cannabis plant can utilize. I've ran a photo and auto together on 20/4 and the photo seemed 'tired' before lights out. Droopy leaves, lack of turgor etc. while the auto was still praying to high heaven.

I like to give my photos a break for 6 hours minimum.

 

[Nio]

There's this study on photoperiods in cannabis that I haven't lost https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9456486/ its pretty cool.

In this image plants under white light and 16/8, plants under purple light at 16/8, plants at white light and 20/4, plants at purple light and 20/4, plants at white light and 24/0 and plants at purple light and 24/0 are compared.

We can see that PItotal (photosynthetic activity) is highest in the well rested 16/8 plants.

Still I'd love to find the one where it's found out that photosynthesis stops after 17 hours in light. That's just phenomenal to me, but I can't share the bloody info without the source.

 

[Zab]

I've read that article myself but same thing I cannot seem to locate it. Did anyone here find it?

 

[Stokes]

Im not sure about all the science but in my tent ive noticed that the plants seem to be much more responsive to light and have better posture with rest. I used to leave it on all the time for seedlings and autos but i start everything with 18/6.

To be fair i have noticed a slowdown in growth of seedlings but other than that i have had zero seedlings issues in almost 2 years

 

[Smokey0418]

Personally using the gas latern method on my photoperiods.
And other than saving hydro , I say there growing quite quickly.
Win win.