What is the ruling on taking plants from graves with the intention of protecting them from death, knowing that they die if not watered continuously?

If the crops are owned by someone, then it is a sin for whoever takes them without the owner's permission, and he must return what he took or its value if it has been damaged. If he does not know the owner, then he must give its value in charity on the owner's behalf. However, if the crops are not owned by anyone, there is no sin in taking them.