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Genetic Variability and Correlation Analysis in Hybrids of Mulberry Silkworm, Bombyx Mori L. for Egg Characters

Md. Kamrul Ahsan
Department of Zoology, University of Rajshahi, Rajshahi

S. M. Rahman
Department of Zoology, University of Rajshahi, Rajshahi

Abstract/ Executive Summary:

The genotypic variability and correlation coefficients were studied in thirty five hybrid populations for five egg characters. Variations among genotypes were highly significant (P<0.001). Phenotypic coefficient of variation was higher than genotypic coefficient of variation for all the characters. Of them unfertilized and dead egg percentage showed highest difference between genotypic and phenotypic coefficient of variation suggesting most influence of environment on these characters. Majority of the characters showed high heritability except hatching percentage. Furthermore total number of egg laying per female showed high genetic advance together with high heritability, which indicates the importance of additive gene effect of this character. The genotypic correlations were higher than phenotypic correlation for majority of the characters under study except DEP Vs TEL and DEP Vs UEP. These low phenotypic correlations could be due to a modifying effect of environment and the association of characters at genotypic level. Hatching percentage, blue egg percentage and unfertilized egg percentage showed both positive and negative significant correlation to each other. Therefore, proper attention should be given to these characters specially total number of egg laid by female and hatching percentage in selection programme for genetic gain in Bombyx. mori.

Keywords: Genetic variability, Correlation, B. mori.

Location: Rajshahi

Start Date:

End Date:

Program Area: Development of Host and Medicinal Plants

Commodity:

Objectives:

To estimate the genetic variation for five important egg characters and correlations among them at phenotypic and genotypic levels for designing suitable breeding programmes.

Methodology:

The materials for this experiment of thirty five F₁ hybrids which were produced by using eighteen bi and multivoltine varieties of silkworm, B. mori. These parents were obtained from the Germplasm Bank maintained at the Bangladesh Sericulture Research and Training Institute (BSRTI), Rajshahi. The crosses were made to produce 35 F₁hybrids The eggs of F₁ hybrids were brushed (3dfls for each genotype) in a randomized design with three replications each. The rearing was conducted in the rearing house No. 2 of the BSRTI, Rajshahi. Scientific technology of silkworm rearing was followed according to Krishnaswami (1978) and Rahman (1983). Data recorded for this study were: total number of eggs laid per female (TEL), hatching percentage (HP), blue egg percentage (BEP), unfertilized egg percentage (UEP) and dead egg percentage (DEP). The collected data were analyzed successively for estimating genetic variability, heritability and genetic advance according to the formula described by Burton & De Vane (1953), Burton (1952), Hanson et al. (1956), Lush (1949) and Johnson et al. (1955). The phenotypic and genotypic correlations were calculated

Source of Information: Univ. j. zool. Rajshahi Univ. Vol. 27, 2008 pp. 13-16 ISSN 1023-6104

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Total number of eggs laid per female showed insignificant correlations with most of the characters except UEP (P<0.01) both at phenotypic and genotypic levels. Hatching percentage, BEP and UEP showed both positive and negative significant correlation to each other. From the study of genetic parameters and characters association, it could be said that these characters had the inherent association to each other specially the characters, total number of egg laid by female and hatching percentage and thus merit prime importance in selection with programmes for genetic gain in B. mori.

Knowledge Management: Journal