Hii!
In order to join post graduate agriculture ourse via ICAR, you have to apply for ICAR AIEEA PG Entrance Examination. If you clear it with a good rank, you will be provided top government Colleges across India to pursue the course.
The Eligibility criteria for the exam states that the Candidate must have completed graduation degree in any relevant Subject stream with minimum 60% marks ( for General category ) and minimum 50% marks ( for reserved category ) from a recognised University.
Hope this helps.
Good luck!