Manifestation of Heterosis and Inheritance of Productive Characters in Simple and Complex Silkworm Bombyx mori L. Hybrid Combinations.
I. Fresh Cocoons Weight and Productivity

N. PETKOV1, Z. PETKOV1 and H. GREISS2
1 Institute of Animal Science, BG-2230 Kostinbrod, Sericultural Experimental Station, BG-3000 Vratza, Bulgaria
2 Agricultural Company “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. I. Fresh cocoons weight and productivity. Bulg. J. Agric. Sci., 9: 237–242

An investigation of heterosis manifestation and inheritance of cocoon weight and cocoon yield characters in simple and complex silkworm Bombyx mori L. hybrid combinations has been carried out at Sericultural Experiment Station Vratza during the period 1997–1999. It was established that using statistical-genetic methods for measuring and evaluation of heterosis in F1, depression in F2 and gene effects at inheritance were suitable for receiving the information for nature of inheritance of cocoon weight and cocoon yield per one box of silkworm eggs characters. It was determined distinct manifestation of heterosis in F1 toward MP and HP for both cocoon weight and cocoon yield per one box of silkworm eggs characters in all tested 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 in cocoon weight and yield of cocoons per one egg box of silkworms characters are due to over-dominance (hp1 > 1) and epistatic gene interactions (hp2 < hp1).

Key words: silkworm, heterosis, dominance, heritability, cocoon weight and cocoon yield