Blogger has introduced new feature for its blogger. With the help of this new feature bloggers can share their comments on Google+. When anyone makes comment on your blog's post that comment is shared to their circles on Google+. To enable Google+ comments for blog you need to do the following below steps.
1. login to your blogger account.
2. click Google+ tab located left side pane.
If you have created multiple pages on Google+ associated with your Google+ profile then you need to select either your profile page or the page that you have created on Google+.
Once you select check box against "Use Google+ comments on this blog" settings have been saved automatically.