[Smeagol]

Do plants use fertilizers when the lights are off, or only when the lights are on, like with CO2?

 

[Darkblade48]

I would think that nutrient uptake happens at all times of the day, as it is not dependent on light (though I am not a plant biologist by education, so take it with a grain of salt).

 

[Smeagol]

Hmm. I would've guessed the opposite, but I'm no biologist either. I might actually drag out my old Bio 101 textbook and see if I can find an explanation in there.

 

[Hoppy]

Most of us have the lights off at night, but many of us see significant growth in the morning compared to when the lights go off. I don't understand how the plants do that, but they certainly do it, or do a great job of pretending to. Like most of you my botanical/biology education was very lacking, and I wish I had taken a few courses in it.

 

[Darkblade48]

Well, plants are constantly growing and incorporating sugars into new tissues. Maybe it's because we go to sleep and haven't seen the plants for 8 hours that it seems growth is significant?

 

[Zapins]

It depends on the nutrient in question.

Basically I think this is what you want to know:

Summary

• PO4 is taken up in the day and night, but much more is absorbed in the light. PO4 is also preferentially taken up by shoots and roots.

• Ca and K are both absorbed in light and darkness but more during the dark.

• Mg is absorbed almost equally in light and darkness.

Phosphate and nitrate uptake thread:
http://www.aquaticplantcentral.com/...87693-nutrient-uptake-night-2.html#post659666

Phosphate uptake in aquatic plants paper:
http://ir.ihb.ac.cn/bitstream/34200...ersed macrophyte Myriophyllum spicatum L..pdf

From:
http://www.aquaticplantcentral.com/...rtilizer-uptake-night-nitrate.html#post666597

 

[Diana]

Plants spend a lot of the night in building new tissues, but I think they grow all the time, too. But yes, they do a lot at night.

At night they respire, that is they burn the sugars they have made during the day, and use the energy to produce new tissue.

Zapins, thank for the links about when plants take in the various nutrients.

 

[Smeagol]

Good info, thanks!