Mendel's experiments on hybridization in Pisum:
Results of a dihybrid cross
To
determine the behavior of the two genes simultaneously, Mendel
made a dihybrid cross of pure-breeding wrinkled yellow
peas with round green
peas, where the alleles for yellow and round were
known to be dominant. All of the F1 generation
showed the
traits due to the dominant alleles for both characters, yellow. and round. When
he
crossed
two F1 hybrids,
he
obtained
in the F2 generation
all
possible
combinations
of traits, in a characteristic 9:3:3:1
phenotypic ratio.