Hello Naveen,
Every composition subnode ( like your item subnode ) has two default associations. They are "To Parent" and "To Root", since your subnode item is a subnode of the ROOT , executing either of them will get you the ROOT data. Execute a Retrieve By Association, with your item node instance keys , node as ITEM , association as "TO ROOT" or "TO PARENT" and the "IV_FILL_DATA" set to true , to collect the ROOT node data directly from the Retrieve By Association call.
Regards,
Indranil.