HI, Some of the courses you can refer to for PG in agriculture after graduation are:

• M. Tech. Environmental Engineering
• M. Sc in Agriculture
• M. Sc in Agricultural Extension
• M. Sc in Agronomy
• M. Sc in Soil Science
• M. Sc in Agricultural Biotechnology
• M. Sc in Agricultural Marketing
• M. Sc in Agricultural Microbiology
• M. Tech in Agricultural Engineering
• M. E in Agricultural Engineering
• Master of Agriculture in Entomology
• Master of Agriculture in Horticulture
• Master of Agriculture in Animal Sciences
• Master of Agriculture in Entomology
• Master of Agriculture in Plant Pathology
• Master of Agriculture in Agricultural Economics and Rural Sociology
• Master In Agriculture And Rural Development

So first you can finalize what course in PG you are looking for so that I can guide you appropriately.

Good Luck.