Hii Anish!
You can definitely go for NID MDes once you complete your 3 years bachelor's degree in any stream. So, botany will also do the job. The eligibility criteria says that the candidate must have completed a 4 year or a 3 year bachelor's degree before July to apply for the exam. Diploma candidates can also apply for it. The upper age limit is 30 years as on 30 June, 2020 for general category and 33 years for reserved category. You can get full details on the official website - www.nid.edu.in
Hope this helps.
Good luck!