Add Google+ comments to WordPress by modifying theme file.

comments.php

/*** 
*   Google+ comments on WordPress
*   More info: http://www.blogsynthesis.com/?p=1072
***/
<script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script>
<div id="plusonecomments"></div>
<script type="text/javascript">
  window.setTimeout(function() {
    var id = 'plusonecomments';
    var divWidth = document.getElementById(id).offsetWidth;
    var width = !!divWidth ? Math.min(divWidth, 750) : 600;
    var url = "<?php the_permalink(); ?>";
    var moderationUrl = "";
    var moderationMode = "FILTERED_POSTMOD";
    gapi.comments.render(id, {
        'href': url,
        'first_party_property': 'BLOGGER',
        'legacy_comment_moderation_url': moderationUrl,
        'view_type': moderationMode,
        'width': width
    });
  }, 10);
</script>