Guidelines for the conduct of tests for distinctness,uniformity and stability-Blackcurrant(Ribes nigrum L.,Ribes dikuscha Fisch.ex Turcz.,Ribes ussuriense Jancz.,Ribes pauciflorum Turcz.)(UPOV:TG/40/7,Guidelines for the conduct of tests for distinctness,uniformity and stability-Blackcurrant,NEQ)