Hello Abhinav!

If you are preparing for your state BSc Agri exams, then the textbooks you used for your 10+2 will be pretty good if you read them regularly.

Otherwise, Arihant publisher's BHU ag book has a good catch on the syllabus required for any bsc agri exam. And rest is your effort in the self-studies. The 5 yr (previous year question ) can help you to understand the depths of the entrance. Other state agri entrance exams have also kind of same pattern as that of BHU Ag exam so the arihant book can guide you nicely.

Another book like Agriculture at a glance, One book written by Nem Raj Sunda, and Arun katyan is also suggested if you want to crack ICAR and BHU. You can also go through a lot of online website that give you simulated mock tests for BSc agriculture exams.

For specifically ICAR UG, you should strictly complete the NCERT books of 11th and 12th . And a guide book of ICAR AIEEA (Agriculture) Entrance Exam Guide (by RP Gupta) is suggested for in-depth learning.

hope this helps:)