Thyroxine을 5, 10, 15$mu$g/ml의 수준으로 이화성 누에 NB18 품종의 유충에 도말처리한 결과 유충, 견사선, 고치, 고치층 등의 무게가 증가되고 유충경과 일수는 단축되는 등, 누에의 실용형질이 개선됨을 확인하였다. 이러한 결과는 전반적으로 10-15$mu$g/ml의 thyroxine 처리구에서 얻어졌고 5$mu$g/ml처리구는 대조구와 유의차를 보이지 않았다. 화아율과 부화율은 thyroxine처리의 영향을 받지 않았고 유충경과일수는 단축되었다.
Effect of topical application with 5, 10 and 15${mu}$g/ml thyroxine on the pre-cocoon, cocoon, postcocoon and silk improvement were studied in bivoltine silkworm NB18 breed of B. mori L. Thyroxine was applied independently on alternate days to silkworm of IV and V instar larvae. The treatment of all different concentrations resulted in a significant increase in commercial characters like larval weight, silkgland weight, cocooning percentage, female cocoon weight and its shell weight and male cocoon shell weight and its ratio, cocoon dimension, length of the filament and its weight and oviposition. However, there was no significant change in larvel weight in 5${mu}$g/ml treated group and larval duration was significantly decrease. But moth emergence percentage and hatching percentage did not show any significant change when compared with that of carrier control.
