On the Regularity of Inheritance of Productive Indexes in Reciprocal Hybrids with the Participation of Genetically Sex-Marked Races of Silkworm (Bombyx mori L.)

N. PETKOV and Y. NACHEVA
Sericultural Experiment Station, BG-3000 Vratza, Bulgaria

Abstract

PETKOV, N. and Y. NACHEVA, 2001. On the regularity of inheritance of productive indexes in reciprocal hybrids with the participation of genetically sex-marked races of silkworm (Bombyx mori L.). Bulg. J. Agric. Sci., 7: 87-90

The present study involved the regularity of inheritance of basic productive indexes (viability of larvae, cocoon weight, cocoon shell weight, length of silk filament and raw cocoon yield per one box) of F1 reciprocal hybrids with the participation of genetically sex-marked silkworm races at egg and larva stages.
It was established that the use of genetically sex-marked silkworm breeds at egg and larva stages as maternal and paternal forms in industrial hybridization influenced the inheritance of the indexes of viability of larvae, cocoon weight, cocoon shell weight, length of silk filament and raw cocoon yield per one box of silkworm eggs.
All indexes studied manifested comparatively higher values and heterosis in reciprocal F1 hybrids where the high parent was used as maternal form.
The inheritance of the indexes both in top/straight (P1 × P2) and reciprocal (P2 × P1) crosses is of the overdominant type (d/a > 1).

Key words: silkworm, reciprocal crosses, inheritance, heterosis