Major plus minor gene mixed inheritance of resistance of soybeans to agromyzid beanfly (Melanagromyza sojae Zehntner).
Inheritance of resistance to beanfly (M. sojae) in soyabean (Glycine max) was studied in the crosses JNCND (resistant) × HJQDHY (susceptible), WXCJGJ (resistant) × PXTED (susceptible) and PXTED × 1138-2 (resistant). P1, F1, P2, F2 and F2:3 plants were evaluated for the number of insects in the stem. Resistance was almost completely dominant and its inheritance was fitted successfully to a mixed 1 major gene and polygene model. Additive and dominance effects of polygenes were different among the crosses, but were less than those of the major gene. Major resistance gene heritability values in F2 plants ranged from 44.2 to 72.9%, and in F2:3 plants from 93.1 to 95.0%. Polygene heritability values were low and had small effects on phenotypic variation.