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Heterosis in Single, Three-way and Double Cross Hybrids of Silkworm, Bombyx mori L.

Published online by Cambridge University Press:  19 September 2011

Sripada M. Udupa
Affiliation:
Department of Sericulture, University of Agricultural Sciences, GKVK, Bangalore-560065 (India)
B. L. Visweswara Gowda
Affiliation:
Department of Sericulture, University of Agricultural Sciences, GKVK, Bangalore-560065 (India)
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Abstract

An investigation was carried out in India, to study the extent of heterosis expressed in single, three-way and double cross hybrids with respect to important economic characters. The results were discussed in terms of relative heterosis (heterosis over mid-parent value) and standard heterosis (heterosis over standard check variety). Significant negative relative heterosis was observed for total larval duration in single and majority of the three-way crosses; whereas it was positive and significant in double cross hybrids. The commercial characters like cocoon and pupal weight, shell percentage, filament length and denier, recorded positive relative heterosis in most of the single and three-way crosses; whereas they were negative and significant in most of the double crosses. In general, higher degree of heterosis was expressed in single crosses followed by three-way and double crosses for the characters studied.

Résumé

Une enquête pour etudier l'importance du degré d'hybridité exprimée chez les hybrides par rapport aux caracteristiques economiques importants chez le ver à soie a étè effectuée en Inde. Les resultats obtenus ont étè analysé en terme d'hybridité relative (hybridité sur la valeur parentale moyenne) et standart (Hybridité sur la verification des varietes). Une hybridité relative d'une valeur negative significative fut observée pendant la durée du developpement larvaire chez le croisement simple et triple contre une hybridité positive et significative chez les souches hybrides resultant d'un croisement double. Les caracteristiques commerciaux par exemple; le poids du cocon, le poids des chrysalides, le pourcentage de la coquille, la longeur et le denier du filament ont enregistré une humidité relative positive chez la majorité des souches hybrides émanant d'un croisement simple et triple contre une valeur significative et negative chez la majorité des hybrides resultant d'un double croisement. En genèral, un degré elèvé d'hybridité a étè exprimé chez le croisement simple suivit du croisement triple et double pour les caracteristiques etudies.

Type
Research Article
Copyright
Copyright © ICIPE 1988

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References

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