Analysis of genetic divergence for classification and evaluation of 37 productive performances in 54 oval cocoon strains of Iran silkworm germplasm
The purpose of this experiment was to analyse the genetic divergence for the classification and evaluation of 37 productive performances in all 54 oval cocoon strains of Iran silkworm Bombyx mori (Lepidoptera: Bombycidae) germplasm. The newly hatched larvae of all strains were reared for experiment under same standard conditions. Studied strains are ranked based on the average of evaluation index method and sub-ordinate function method. From the obtained results, it was clear that different strains of silkworm B. mori showed different performances based on productive traits. The analysis of variance regarding the studied traits showed that different strains have significant difference for traits (P < 0.01). Totally, W2-11-19-2 (2030.234), W2-11-19-3 (2025.089), BH-4 (1981.516), 104×110 (1963.656) and 17 (1935.046) showed higher evaluation index values. W2-11-19-3 (19.868), W2-11-19-2  (2030.234), BH-4 (18.857), 104×110 (18.560) and 17 (17.917) showed higher sub-ordinate function values. All strains with the same origin did not group together because they had different biological and development performance. The main groups were also divided into separate sub-groups. Three sub-groups included various strains. Several strains were grouped together and far from other silkworm strains, indicating that they might be suitable for future crossings, maintenance of parental strains and hybridizations with peanut cocoon strains so as to maximize heterosis and to avoid depression inbreeding. After evaluation by two statistical methods (evaluation index method and sub-ordinate function method), some oval type strains that stood within high ranks were identified as potential parents for further breeding programme.
Key words: Hierarchical agglomerative clustering, oval cocoon, silk, germplasm bank, performance.