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Two genetic lines, M1 (P₁) and M60 (P₂) were crossed to determine the number of effective factor pairs controlling fruit weight. By applying the partitioning method of genetic analysis, it was found that two genetic lines were differentiated by two effective factor pairs. The data indicated the existence of partial phenotypic dominance for lighter (P₁) over heavier one (P₂). The genotypes of P₁ and P₂ were designated as AABB and aabb respectively. In studying factor interaction, dominant allele exhibited partial dominance over its recessive allele in all genotypes, except AaBB and aaBb. The degree of dominance with regard to both A and a, and B and b was dependent upon the genetic milieu. In substitution of a for A, the different genotypes did not have the same effect upon fruit weight, as did the substitution of b for B in the corresponding genotypes, but the effect of (A-a) factor pair on fruit weight was a little larger than those of (B-b) factor pair. To manifest the nature of inheritance in fruit weight, the diallel crosses were made. Fruit weight showed partial dominance, and the heavier one appeared to be controlled by recessive genes. Heritabilities, broad and narrow sense, were very high. GCA (general combining ability) and SCA (specific combining ability ) were highly significant, and mean square values of GCA were larger than those of SCA. The result from partitioning method analysis was comparable to those of diallel analysis.
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