Manifestation of Heterosis and Inheritance of Productive Characters in Simple and Complex Silkworm Bombyx mori L. Hybrid Combinations
IV. Number and Weight of Normal Eggs per Lying

N. PETKOV1, Z. PETKOV1 and H. GREISS2
1Institute of Animal Breeding, BG-2230 Kostinbrod, Bulgaria
2Agricultural firm "Agromier SAE", Eg-11211 Cairo, Egypt

Abstract

PETKOV, N., Z. PETKOV and H. GREISS, 2003. Manifestation of heterosis and inheritance of productive characters in simple and complex silkworm Bombyx mori L. hybrid combinations. IV. Number and weight of normal eggs per lying. Bulg. J. Agric. Sci., 9: 699–702

An investigation of heterosis manifestation and the inheritance of number and weight of eggs per lying characters in simple and complex silkworm Bombyx mori L. hybrid combinations has been carried out at Sericultural Experiment Station Vratza during spring season of 1997–1999. Distinct manifestation of heterosis was determined for number and weight of eggs per lying characters in F1 toward MP and HP in all tested simple and complex F1 crosses. In all cases, when heterosis in F1 was highly marked, it was observed the bigger depression in F2. Genetic parameters for degree of dominance in F1 (hp1) and F2 (hp2) showed that heterosis for number and weight of eggs per lying characters are due to over-dominance (hp1 = 3.46–12.50 and 4.33 – 50.00) and epistatic gene interactions (hp2 < hp1). Dominant epistatic gene interactions (dd) had relatively most important influence, followed by aditive-aditive epistatic gene interactions (aa) and from the two kinds of gene effects, dominant ones (d) was the most important.

Key words: heterosis, heritability, and number of eggs per lying and weight of eggs per lying