Study of the Average Values and Variability of the Basic Productive Indexes of Double, Triple and Tetra-cross Hybrids of Silkworm (Bombyx mori L.)
II. Summer Feeding SeasonN. PETKOV, L. IGNATOVA, Y. NACHEVA and P. TZENOV
Sericultural Experiment Station, BG-3000 Vratza, Bulgaria
PETKOV, N., L. IGNATOVA, Y. NACHEVA and P. TZENOV, 2000. Study of the average values and variability of the basic productive indexes of double, triple and tetra-cross hybrids of silkworm (Bombyx mori L.). Bulg. J. Agric. Sci., 6: 681-686
A comparative study of the average values and variability of the basic productive indexes of double, triple and tetra-cross hybrids of silkworm was carried out during the summer season of silkworm feeding with the participation of the same parental forms.
The average results for the separate hybrid types show that statistically significant higher values of the most important silkworm biological indexes and technological cocoon traits have been obtained for the complex (triple and tetra-cross) hybrids.
In terms of the technological indexes, characterizing silk filament length, weigth and denier, double crosses, followed by triple and tetrahybrids, showed the comparatively highest values.
In terms of reproducive indexes, characterizing the number and weight of good eggs per laying, the highest values were obtained for the tetra-, followed by the triple hybrids and the lowest- for double-cross hybrids.
The relatively highest variability of the basic selection indexes was reported for the tetrahybrids, followed by triple and double hybrids.Key words: Bombyx mori L., double-cross hybrids, triple-cross hybrids, tetrahybrids, productive traits