Plant natural rythms?

Hi!

I believe that it is possible to adapt your plants to your own light/dark periods. The plants only respond to the number of hours when lights are on and off, they don't have a alarm clock ringing in the morning so to speak but the daylight in your room might affect their Circadian rhythm. I thought I had an answer but maybe not!

 

Actually, it has been scientifically proven that most plants have very small brains and probably can't tell the difference. Just toying with you, Gerry!

 

Isn't the only potential problem with shifting the timing of "daylight" the fact that it will be actual daylight during what the plants will be treating as night time? It looks to me like even that isn't a serious concern because the intensity of the room light during daytime is still way less than the intensity with the tank lights on. It appears to be about 1% or so of the tank light intensity. You can sort of demonstrate this by taking a photograph inside your house in daylight with no flash. You won't get much of a photo unless your camera is capable of wide lens openings and slow shutter speeds. But, to our eyes it appears that the room is well lit. Our eyes are just extremely effective at using whatever light level exists.

 

Gerryd: Maybe I don't have a good answer. But I think that they can adjust to your light periods but I'm not qualified to give any good answers.
But what I know is that some plants can be very sensitive to light in their daily and annual rythms. I know that a flower that need complete darkness for several weeks to do a second blooming. If you expose to just a flash of light it might not bloom again.
That is an extreme and I don't know how aquatic plants reacts to different light periods.

 

If you cover the back and sides of the tank with black paint or some other black covering, this could help reduce the ambient lighting and you could determine if this makes a difference. Or just to experiment, put a black garbage bag over the tank, then before your lights come on in the afternoon, remove it and see if the plants have already opened their leaves. However, it appears to me that plants do somehow have a memory of how long the lights have been on/off (kind of like jet lag for humans) so it may take a few days of doing this to see an effect. I say this because when I changed my photoperiod to later in the day recently and increased it to 12 hours, the plants started closing up around 9pm even though the light would stay on until 10. After a week or so, I didn't see this anymore.

 

My own observations are that plants are primarily triggered by time and next adjust to the light available, then all my observations have been with ambient light available.

The plant shows "woken up signs" even before my delayed timer-set lights on period and don't go into "sleep position" till lights off period.

I have no observation from total darkness from ambient light and I too would be quite interested in knowing how plants behave under such conditions.