Your testing the hypothesis that there are two genes A and B which are both required to be active to form the colour purple. 'A' is dominant over 'a' and 'B' is dominant of over 'b'. Each kernel will have two copies of A and B First complete the information of the parent, F1 and F2 phenotype and genotype and the F2 gametes.
Draw a 4x4 Punnett Square for the F2 generation (using the F2 gametes) and determine the expected ratio of phenotypes