Is it wrong to say "every line has ten trees"? Should I use "each" instead of "every" ?
It is correct if what you mean is
every (single) line has ten trees
which is how it would be understood, "every single" is idiomatically equivalent to "all" or
all the lines have ten trees
which would have the same understanding as
each line (of trees) has ten trees
each and every line has ten trees.
gets used for clarity and emphasis but a slightly verbose.