SEOUL, South Korea — An 81-year-old South Korean fashion model fell short in her bid to become the oldest Miss Universe contestant after competing in the country’s national pageant against rivals old enough to be her grandchildren.

Dressed in a beaded white gown, the silver-haired Choi Soon-hwa strutted across the stage and performed in a singing contest at the Miss Universe Korea pageant held Monday at a hotel in South Korea’s capital, Seoul.

She missed out on the crown but did take…