The best way to determine the genotype of a plant with dominant color flowers is to perform a test cross with a homozygous recessive plant. This involves crossing the unknown plant with a plant that has the recessive phenotype. If the unknown plant is heterozygous, then approximately half of the offspring will show the recessive phenotype, and if the unknown plant is homozygous dominant, all of the offspring will have the dominant phenotype. This test cross can confirm the genotype of the unknown plant.
