India’s most popular, and powerful, yoga guru rejected an appeal by Prime Minister Manmohan Singh on Wednesday to call off a hunger strike against corruption, the second major challenge to a government losing its authority due to rampant graft. The charismatic Swami Ramdev, who dons a saffron cloth thrown over his bare torso, runs a $40 million-a-year global yoga and health empire and has millions of followers: some 30 million viewers tune into his daily yoga TV show.