The Journal of Silk Science and Technology of Japan
Online ISSN : 1881-1698
Print ISSN : 1880-8204
ISSN-L : 1880-8204
Change of cocoon filament quality and raw silk yield in the F1-hybrid of high-strength silk thread producing silkworm strain
Masatoshi Iga Tetsuya IizukaEiji OkadaKenichi Nakajima
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2021 Volume 29 Pages 51-57


  Silk has excellent original properties. It is garnering attention not only as a material for clothing but also as an industrial material. Development of raw silk with even greater high strength and strain is anticipated in both cases. Raw silk made from the cocoon of MC502, a high-strength silk-thread producing Chinese silkworm strain, has greater than 5 g/d strength, although the yields of the cocoon and raw silk were lower than those of commercial silkworm strains. Therefore, MC502 was crossbred to five characteristic silkworm strains. Effects on cocoon thread character and raw silk yield were evaluated to improve the cocoon and raw silk yields necessary for the practical use of MC502. All F1-hybrid MC502 showed a significant increase of cocoon and cocoon shell weight. Furthermore, single cocoon reeling testing revealed that the cocoon filament length and size curve were changed relating to the crossbred silkworm strains. In addition, crossbreeding affected the reeling test score. The score was improved in most cases. Especially, a significant increase of raw silk percentage was observed when MC502 was crossbred with J137, a Japanese silkworm strain of standard character. All F1-hybrid MC502 maintained the high-strength character of MC502. The strengths of their raw silks were much higher than those of commercial silkworm strains. Especially, almost equal strength to that of MC502 was observed when MC502 was crossbred with J137, a thin silk-thread producing Chinese silkworm strain C515, and a high-strength silk-thread producing Japanese silkworm strain MN502.

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