why were farmers reluctant to grow opium in india
Opium had to be grown on very good land in which the soil is fertile [manure]. The farmers grew pulses on this land. Thus, if they grow opium on this land, they will not have good land to grow pulses.
They were paid less for opium production.
Opium required lots of care and nurturing. If the farmers spend lots of time on this then they wouldnt have time to grow other crops.