how many mana can you put down in a turn

[Sektor]

how many mana can i play in one turn

[Kenji]

You can play one land per turn, and then only during your own turn. Mana isn't a tangible object, so you can't "put down" any mana in a given turn.

As a reminder -- lands are not mana, and mana is not land. Land, such as Forest, produces mana when you tap it. Think of it this way: Land is to mana as Cows are to milk