Comparison of performance of hybrids obtained by crossbreeding of new lines of Iranian silkworm and identification of superior hybrids

The aim of the present study was to investigate the performance of the hybrids obtained by crosses of the six Japanese silkworm lines named IRA1, IRA3, IRA5, IRA7, IRA9, and IRA11 and six Chinese silkworm lines named IRA2, IRA4, IRA6, IRA8, IRA10, and IRA12. The new hybrids derived from these lines along with available commercial hybrids (as control groups) for six traits including cocoon weight, cocoon shell weight, cocoon shell percentage, best cocoon weight, pupation rate and best cocoon pupation rate were measured and recorded in spring 2020. The IRA7×IRA6 and IRA7×IRA12 hybrids had more performance in comparison with commercial hybrids in terms of productive traits including cocoon weight and cocoon shell weight (P < 0.01), but, when productive and viability traits (pupation rate and best cocoon pupation rate) were considered together in an evaluation index, they were not among the selected hybrids. Commercial 31×32 hybrid in terms of cocoon shell weight and cocoon shell percentage had more performance in comparison with the other hybrids (new and commercial) (p<0.01). Hybrids had a significant difference for pupation rate and best cocoon pupation rate (P < 0.01), and the IRA5×RA12, IRA1×IRA10 and IRA11×IRA6 hybrids showed the lowest mean for both traits in comparison to other hybrids (P < 0.01). The results obtained from the present study indicated that seven hybrids including IRA9×IRA2, IRA11×IRA2, IRA3×IRA6, IRA3×IRA2, IRA7×IRA4, IRA7×IRA10 and IRA7×IRA8 were greater than the minimum set for every six traits. Therefore, they can be used to supply the country's required silkworm eggs.