I'm a 1st-year student of botany (Hons.) but I don't like the subject much. I like teaching. Can I pursue B.Ed directly after 12th?

It is good to see your expressions. If possible, convince your parents and take another course you like, which is career oriented as well. Otherwise, remember, no course is worth, it is you who make it worth and interesting. Botany is about life, it can give you great knowledge.