After B.Sc in botany you have so many options but it depends on what do you really want to do.
you can go for msc in biotechnology, microbiology, plant genetics, human genetics (these are some popular courses).
After that you can prepare for NET, JRF. You can opt for MBA. For that you have to give entrances like CAT( accepted by top b-schools), XAT, SNAP, MAT, CMAT, NMAT.
There are many institutes/ universities who advertise positions for research work and they look for candidates with Msc botany.