Imported Grass resolution drops 4x against original size

Hello I have a strange problem, always when I import an grass texture to unity its resolution dramatically drops. I am using as png as psd with alpha channel. It is not only problem of this grass, but all of I tried to import. This bug also ignores if resolution is square of 2 or not. Do you have any idea how to make grass looks nicer? It seems like there is something like 256x256 max global grass resolution or so. Also I am wondering, why today is still not an 8 bit alpha channel on grass or trees. Then we could use lower resolution to get same result and it should not be so computive power killing.. But back to the problem. The original size of picture is 1024x1024 and unity downsized it to cca that 256x256 or less. Thank you for your help. More details in screenshot.

[1]: /storage/temp/54344-screenshot-2015-09-15-142957.jpg