"Why do you confine yourself to Gujarat?" Badal asked, triggering more clapping.
In his speech otherwise devoted to agriculture, Badal described Modi as "desh ka mahan neta" (great national leader) and as "Sardar Modi".
In an earlier address, Madhya Pradesh agriculture minister Ramkrishna Kusmariya ignited a roar of applause in the hall when he said Modi was "Bharat ka bhavishya" (future of India).
Modi has been named the Bharatiya Janata Party's election campaign chief and is widely tipped to be the party's prime ministerial candidate ahead of the next Lok Sabha election.