Can the reply in forums be unsubscribed?

You can unsubscribe them. While replying unselect the subscription button. Alternatively you can manage the subscriptions on "My Profile" page of forums(Not the main menu but located just above first post of the topic on forums.)

Also when u give quick reply .. it is not subscribed...

Getting notification to every post is annoying but its helpful sometimes...

It was helpful because the content posted by members also was there in mail.But now only the link to the discussion comes.So it became annoying.