我有一个多维数组$ md_array，我想将更多元素添加到子数组recipe_type和美食中，这些美食来自从表中读取数据的循环。

在循环中，我为每行创建一个新表$ newdata：

$newdata =  array (
          'wpseo_title' => 'test',
          'wpseo_desc' => 'test',
          'wpseo_metakey' => 'test'
        );

然后，array_push()我需要将$ newdata数组追加到以下多维数组：

$md_array= array (
     'recipe_type' => 
      array (
        18 => 
        array (
          'wpseo_title' => 'Salads',
          'wpseo_desc' => 'Hundreads of recipes for Salads',
          'wpseo_metakey' => ''
        ),
        19 => 
        array (
          'wpseo_title' => 'Main dishes',
          'wpseo_desc' => 'Hundreads of recipes for Main dishes',
          'wpseo_metakey' => ''
        )
      ),
     'cuisine' => 
      array (
        22 => 
        array (
          'wpseo_title' => 'Italian',
          'wpseo_desc' => 'Secrets from Sicily in a click',
          'wpseo_metakey' => ''
        ),
        23 => 
        array (
          'wpseo_title' => 'Chinese',
          'wpseo_desc' => 'Oriental dishes were never this easy to make',
          'wpseo_metakey' => ''
        ),
        24 => 
        array (
          'wpseo_title' => 'Greek',
          'wpseo_desc' => 'Traditional Greek flavors in easy to make recipies',
          'wpseo_metakey' => ''
        )
      ) 
    );

使用array_push将新元素（数组）添加到recipe_type数组的语法是什么？我永远无法绕过多维数组，我有点困惑。