Eligibility Criteria for appearing in the UPSC Agriculture Optional Subject Exam:

To appear in the UPSC Agriculture Optional Subject Exam, candidates must fulfill the following eligibility criteria:

Nationality:
- The candidate must be a citizen of India, or
- A subject of Nepal, or
- A subject of Bhutan, or
- A Tibetan refugee who came over to India before 1st January 1962 with the intention of permanently settling in India, or
- A person of Indian origin who has migrated from Pakistan, Burma, Sri Lanka, East African countries of Kenya, Uganda, the United Republic of Tanzania, Zambia, Malawi, Zaire, Ethiopia, and Vietnam with the intention of permanently settling in India.

Age Limit:
- The candidate must have attained the age of 21 years and must not have exceeded the age of 32 years on the 1st of August of the year of examination.
- There is relaxation in the upper age limit for candidates belonging to certain categories:
- OBC: 3 years
- SC/ST: 5 years
- Defense Services Personnel: 3 years
- Ex-servicemen including Commissioned Officers and ECOs/SSCOs: 5 years
- Blind, deaf-mute, and orthopedically handicapped persons: 10 years

Education Qualification:
- The candidate must have a degree in Agriculture from a recognized university.
- Candidates with an equivalent qualification in Agriculture or allied subjects can also apply.
- Candidates who have appeared in the final year of their degree examination and are awaiting results can also apply, but they must submit the proof of passing the qualifying exam with their application for the Main Examination.

Number of Attempts:
- General category candidates can attempt the exam six times.
- OBC category candidates can attempt the exam nine times.
- SC/ST candidates can attempt the exam unlimited times till they reach the upper age limit.

Physical Standards:
- Candidates must be physically fit as per the physical standards for admission to the Indian Agricultural Research Institute.

It is important for candidates to carefully read and understand the eligibility criteria before applying for the UPSC Agriculture Optional Subject Exam. Meeting the eligibility criteria is a prerequisite for appearing in the exam.