Undefined index: und on search-result.tpl.php for Taxonomy Terms
It's either that your field has a set language (not 'und' which stands as 'undefined') or that you have no value for field_my_taxonomy_term.

Either way you should add this control before your foreach (I also rewrite it to fit Drupal best practices) :

&lt;td class="field-item"&gt;
  &lt;?php $str = ''; ?&gt;
  &lt;?php if (isset($result['node']-&gt;field_my_taxonomy_term[LANGUAGE_NONE]) &amp;&amp; $result['node']-&gt;field_my_taxonomy_term[LANGUAGE_NONE]): ?&gt;
    &lt;?php foreach ($result['node']-&gt;field_my_taxonomy_term[LANGUAGE_NONE] as $obj): ?&gt;
      &lt;?php $str .= l($obj['taxonomy_term']-&gt;name, 'taxonomy/term/' . $obj['tid']) . ',&amp;nbsp;'; ?&gt;
    &lt;?php endforeach ?&gt;
    &lt;?php print trim($str, ',&amp;nbsp;'); ?&gt;
  &lt;?php endif ?&gt;
&lt;/td&gt;