Step 1: Purpose of the National Genebank.
The National Genebank in India was established to conserve plant genetic resources, ensuring biodiversity preservation and food security for future generations.
Step 2: Establishment year.
- It was started in 1992 at the National Bureau of Plant Genetic Resources (NBPGR), New Delhi.
- Other years given are incorrect:
- 1983: Too early, before formal establishment.
- 2001: Incorrect, already functional before that.
- 2023: Clearly wrong.
Step 3: Conclusion.
The correct year is 1992.
Final Answer: \[ \boxed{\text{The National Genebank was started in 1992.}} \]