Look this problem:
and this:
How to solve this problem.
For smooth edges turn on anti aliasing in the project quality settings. Also check for black pixels at the top of your texture and remove/change the colour.
I have solved this problem:
By enabling “Use Direct3D 11” from File>Build Settings>Player Settings>Other Settings>
Look it:
[17702-3d+maze+game.jpg|17702]