Abstract:Two materials with a relatively wide genetic relationship(GS=0.58),Taiyan 7 and Burley 21,were employed to study the effect of double-primers on the polymorphism of the RAPD PCR reaction,using the standard RAPD procedure(single primer) as a reference.Results showed that the double-primers reaction could amplify more polymorphic bands than the standard RAPD technique.The application of the double-primers RAPD technique could,therefore,be an effective and economical method to improve the selection efficiency of polymorphism molecular markers.