Scientific research

Knight and Rogers (1953, 1955) postulated the existence of five incompatibility alleles, at a single locus, in the three self-incompatible but cross-compatible cacao genotypes studied by them. The five alleles differed in dominance, but two were equal; the same dominance sequence, S 1 > = S 2 > S 3 > S 4 > S 5 was exhibited in both male and female parts of the flower. Their criterion of compatibility and incompatibility was the retention or fall, respectively, of hand-pollinated flowers guarded from insect visits.