Hi Raja,
You have selected Planning Mode - 1 (Adapt planning data (normal mode)) which will update if any changes are there to the existing planned dependent items. For Eg: You have changed the FG PIR from 1500 to 1600 then executed MRP MD02 then for the already planned dependent items quantity also will be changed accordingly.
If you select Planing Mode -3 then it will delete and recreate the planned orders/purchase requsitions for all the dependent materials which can be displayed on the above page. Hope its clear.
Thanks & Regards,
Ramagiri