Hey,

These are some of the good private institutions you'll find in south india for btech in agriculture- 

A. Veeriya Vandayar Memorial Sri Pushpam College (Autonomous)

Adhiparasakthi Agricultural College

Ayya Nadar Janaki Ammal College (Autonomous)

Ayyar Bawan - School of Catering and Hotel Management

College of Forestry

Centurion University of Technology and Management - CUTM

College of Agricultural Technology - CAT Theni

Dr. MGR Educational and Research Institute

Hope this helps. 

• Acharya NG Ranga Agriculture University, Hyderabad
• Vanavarayar Institute of Agriculture, Coimbatore
• Shrimathi Devkunvar Nanalal Bhatt Vaishnav College for Women (Evening), Chennai
• Vellore Institute of technology, Vellore
• RVS agriculture college