Dihybrid cross is cross occuring between 2 genes having 2 distinct traits. Genotypic ratio of dihybrid cross can be calculated by punnet square. For a normal dihybrid cross genotypic ratio is 1:2:1:2:4:2:1:2:1. So genotype are 9. We can calculate it faster by using genotype number= 3^n where n= number of genes or traits involved.