How to ripen Papaya before plucking from plant

Dear Sri sir,

The fruits in my farm are ripening very unevenly i.e., buyers are not willing to buy unless they have atleast 1.5 tons of fruits with 2 or 3 yellow lines. But in my farm only 50 to 60 fruits have yellow lines. So I was wondering if there is any way to induce ripening (preferably natural method) so that I can get more fruits during every cutting with yellow lines to offer to buyer.

Thanks
Guru