Can a landlord take a charitable tax deduction for subsidizing rent?

Yes - as long as you can show that the fair market price for rent is higher than what you are charging. For example if you have multiple units that are essentially identical and can show that other tenants pay $X./month whereas you are only charging $Y/month for a 501c3 organization, you can claim the difference as a charitable donation.

However, if your subsidized tebant is an individual, then no deduction is alliwed.

However, if your subsidized tebant is an individual, then no deduction is alliwed.

Right - the lease holder must be a 501c3 charitable organization. If this is an apartment you may have a situation where the charity rents from the landlord in order to provide housing for an employee, but again as long as the lease holder is a 501c3 charity it should be OK.

Could someone point me to the literature that allows a charitable deduction between fair market value of the rent and the below-market rent actually paid. It looks to me that this is a donation of a partial interest and no charitable deduction would be allowed.

However, I am not sure what the OP means by subsidized rent. If the landlord charges the fair market value and then donates cash back, then that would be deductible.