Hii!
Although you haven't mentioned the name of the course you want to pursue in Assam Agricultural University, let me tell you the general Eligibility criteria.
It states that the Candidate must have passed class 12th with minimum 50% marks in science stream from a recognised Board of education.
The link given below May help you with detailed information-

http://www.aau.ac.in/academics/eligibility

If you fulfill the respective course's criteria, you can apply for it.
Hope this helps.
Good luck!