Strange plant behaviour

Hi prof, I have this Red Cabomba ( Cabomba piauhyesis ) whick seems to open and close its leaves, I am realy curoius to know why it does this? Here are some photos, the first taken in the morning and the other in the evening.

 

Hi Sailing Derrick,

Yes, I know this business with particularly the red cabomba as I also grow it. Plant physiologists refer this movement as "nastic" movement. Many flowers also do something similar in that they close at night, others plants don't bother. I do not actually know what the advantage of this is supposed to be except that it may protect the flower or plant against something that night eat it at night. However, this movement is perfectly normal and actually cannot be stopped. In the evening, before I switch off the lights over my tank with the cabomba they are also all closed.

Interesting observation!

Kind regards,

Dirk

 

Thanx Dirk, much appreciated...

Derrick

 

It's basically the plant's natural reaction for day & night times (it's body clock). Your Limnophilas also close up at night time. Hygro Corymbosa also does.

Very cool

Here's some copy&paste off Wiki

Nyctinasty is the circadian rhythmic nastic movement of higher plants in response to the onset of darkness. Examples are the closing of the petals of a flower at dusk and the sleep movements of the leaves of many legumes.
Nyctinastic movements are associated with diurnal light and temperature changes and controlled by the circadian clock and the light receptor phytochrome. Several leaf-opening and leaf-closing factors have been characterized biochemically.
Anatomically, the movements are mediated by pulvini. In the SLEEPLESS mutation of Lotus japonicus, the pulvini are changed into petiole-like structures, rendering the plant incapable of closing its leaflets at night.

 

This behavior is a response to a shortage of CO2 and surplus of light.

Without CO2 the plants are unable to use the energy captured by the chloroplasts in the leaves. This energy, without CO2 to absorb the energy, can cause a build up of the energy (in the form of ATP and NADPH). The last one is the problem. NADPH is an electron acceptor (see http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html). If NADPH builds up (i.e. NADP+ is depleted) there is nothing to accept the electrons which can then react with other molecules to form free radicals which will damage the plant (leaf burn). To prevent this, the plant will decrease the angle of its leaves relative to the light source and in so doing capture less light, and thus less energy. Without the light there is no free radical generation and the leaf survives.

Land plants do the same. If you watch your garden plants you will notice that during the heat of the day, the plants will angle their leaves to receive as little light as possible. There isn't enouh CO2 in the atmosphere to support the rate of photosynthesis needed to use the ATP and NADPH.

If you increase the CO2 levels or decrease the lighting you will notice that these movements stop. They are different to nastic movements which are purely circadian.

tt

 

Interesting T...makes sense what you said.

 

Hello "Solex69",

Its actually more complicated... You can have a surplus of CO2 and still get the same effect simply because the capacity to use the CO2 is exhausted. Once the system begins to back-up at one point, you get a traffic jam all the way to the begining.

I assume that CO2 is the problem because when I started to increase the CO2 content in my old planted tank when the Hygrophila was doing the same trick as the Cabomba mentioned the behavior stopped (I didn't have a lot of light over my tank then). When I increased the light intensity the behaviour came back.

After only a few minutes of darkness the plant would be ready for more photosynthesis.

The reason I dismissed nastic movement was simply because the plants receive the same volume and intensisty of light all through the day (assuming your tank isn't near the window) which means they have no ability to regulate their circadian clock any better than light on/off. The nastic movements of plants are stimulated by a change in light intensity. This generally doesn't happen in fishtanks.

tt4n

 

So am I right in assuming then to resolve this, the light intensity should be lessened? Or for that matter, the amount of CO2 released into the tank?

I must admit, once I added CO2 to my 1.2m tank, my cabomba stopped closing up, but my Hygro Corymbosa is still doing so.

So it would then come back to having normal light times applied to your tanks (leaving the CO2 element out of this for now) to prevent the point where the light intensity mark is reached for the plants? IE, if a person sees this behaviour with his plants, he could take that as a sign of havign to switch off his lights earlier perhaps?

Cheers
Dale

 

There is nothing to resolve. This is a natural response. Once the lights go off and the plants can process the CO2 they have fixed the NADP+ pool will be replenished and the leaves will "reset".

Also, you can't keep all the plants satisfied all the time. Hygro corymbosa is one of those bog plants that has been pushed into an unnatural setting---i.e. your aquarium. You will have to push the CO2 up to the point where the fish will be unhappy before the plant will satisfied.

Best adhere to a daily light cycle of like 8 hours on, 14 hours off or something like that... This reorientation of the leave will not harm the plant. It is its defense mechanism and works very well.

In the case of my Hygrophila polysperma, I never really bothered with it. It grew like a weed, had good colour and was happy. Just every night, about 20h00 the leaves would "close". In the morning it was back to normal.

This behaviour isn't anything to worry about. Plants in nature do it too. if they do this, they are getting all the energy they need to grow. If the plants are growing, then they are happy and if they are happy, why mess with the system?

Kind regards

 

Ah, thanks for clearing that up T

Trust me, I'm a very firm believer of "if it works, don't fiddle with it"
My light cycles vary on a daily basis and has worked for fine for me

Cheers mate
Dale