IR36 has a better resistance for

Solution (By Examveda Team)

IR36 has a better resistance for Brown plant hopper.
Khush developed IR36, a semi-dwarf variety that proved highly resistant to a number of the major insect pests and diseases that raised farmers' rice yields and drove down prices of the staple food for Asian families.
IR36 eventually became susceptible to the brown planthopper and diseases transmitted by leafhoppers. IR36 would prove itself to be valuable not only to farmers but to IRRI as well.