Short answer : around 0.47 atm
World's highest plants discovered growing 6 km above sea level
If this Air Pressure Calculator is to be believed that should be 0.47 atm, so for plants 'the lowest pressure at which plants can survive is around 0.47 atm' seems to be your answer.
The air pressure on Mars is 0.00628 atm, so no, plants can't survive on Mars, if ...
A catalytic site on a subunit of Photosystem II is responsible for splitting water via photo-oxidation. This site, called the Oxygen-evolving complex (or OEM), uses energy from sunlight (which is converted to electrochemical potential energy in the photosystem's reaction center) to accomplish this task.
See Barber (2012)1 for an ...
I believe it's a Dieffenbachia, see also this question & answer from Gardening.SE:
though I am not sure of the species, it could be Dieffenbachia seguine which shows a similar coloration and is one of the taller species (I believe some of the ...
No, the lowest pressure at which plants can survive is not around 0.47 atm.
It is 0.07 atm or less in the case of ryegrass. And it's the total pressure. Not partial pressure of one of the constituent gases.
See this article: