The store houses seed and germplasm collections that are of world importance in the struggle to protect biodiversity. The United Nations has declared 2010 to be the International Year of Biodiversity.
The open ceremony took place during HRH's two-hour visit to SCRI's new, multi-million pound glasshouses at its Invergowrie site.
The Princess Royal met some of the 350 staff and workers at SCRI and also paid a visit to the research institute's 118 hectare farm at Balruddery in Angus.
The farm carries the official title 'Centre for Sustainable Cropping' and is part of a 20-year experiment to find ways of growing more and healthier crops with fewer resources and minimum damage to the natural environment and biodiversity.
The Princess Royal was guided around the research centre by its Director, Professor Peter Gregory.
He said: "This is a great honour for SCRI and a real boost to the scientists and staff here. The National Seed Store and Balruddery Farm are home to important elements of natural biodiversity which we use to improve commercial varieties."