Yes, you can do MSc in Forensic Science after doing BSc in botany.

Minimum eligibility criteria for M.Sc. in Forensic Science course may vary across institutes. Primarily, the criteria include:

• B.Sc (Hons) in Physics or Applied Physics or Chemistry or Analytical Chemistry or Biochemistry or Toxicology or Industrial Chemistry or Mathematics or Applied Mathematics or Statistics or Biology (Zoology or Botany or Genetics or Biotechnology or Biochemistry or Physical Anthropology) with 50% marks in aggregate from a recognized University.
• B.Sc of minimum 3years duration with at least 50% marks in aggregate from a recognized University. Also, the candidate must have studied from the at least 1st year (2 semesters) of the 3 years degree course any 2 subjects out of Physics, Mathematics, Statistics, Chemistry, Biology (Zoology/Botany/Genetics/Biochemistry/Biotechnology/Physical Anthropology).
• B.Sc Forensic Science with at least 50% marks in aggregate from any recognized university.
• B.Tech (Mechanical or Civil or Electronics or Instrumentation or Chemical Engineering or Computer Science) with at least 50% marks in aggregate from any recognized University.