kid1293, RedKetchup, thank you! I was afraid that it will have something to do with that .srsl files.
But as I can see, is wouldn't look transparent in Blender. And I opened the crop model and there is a camera, centered at some place near the crop. Is it important?
UPD No, opened this model in a large scale and saw that it looks transparent in blender too. I noted that in lettuce model the material has different 'transparency' parameters, but when I applied such parameters to my oats and rendered it, only stem was left
And it was made of dots, like if it was semi-transparent.