improvement of performance in six silkworm f1 hybrids by means of nine selection generations using index system

abstract effect of selection index in four iranian commercial lines (107, 110, 153 and 154) on performance of their hybrids including 107 ×110, 110×107, 153×154 and 154×153 was investigated. selection index program was performed on all 3p commercial lines during 9 generations. next generation parents of 3p lines were selected in each generation, by construction of selection matrix based on heritability parameters, correlations between cocoon weight, cocoon shell weight and cocoon shell percentage and also phenotypic mean of traits. in the 10th generation, 2p populations (produced by random cross of 3p) were mated randomly and p (parent) silkworm eggs were produced by random mating of 2p population. p populations in selected and random groups were reared under rural (silkworm rearing house) conditions. control p population was produced by crossing 2p populations (produced by non-selected 3p lines). f1 hybrids of control group (non-selected) were reared simultaneously. from obtained results, it was showed selection by index method in 3p lines has significant effect on performance improvement of silkworm f1 hybrids. there was significant difference for cocoon weight between two selected (1.556gr) and non-selected (1.486gr) groups (p<0.05). meanwhile shell cocoon weight had significant difference between two selected (0.344gr) and non-selected (0.310gr) groups (p<0.05). also, cocoon shell percentage showed significant difference between two selected (22.268%) and non-selected index (21.037%) groups (p<0.05).