University of Guilan Caspian Journal of Environmental Sciences 1735-3033 5 1 2007 01 01 Key principles for breeding spring-and-autumn using silkworm varieties: from our experience of breeding 873 × 874 57 61 980 EN Y. Zhao 1- Institute of Life Sciences, Jiangsu University, Jiangsu 212013, China 2- Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212018, China) Journal Article 1970 01 01 The successfully breeding of the hybrids 873?874 had settled the problem that the yield was not uniform to the silk quality in silkworm varieties. In this paper, we illuminated the key technology, principle, hints and methods for selection in breeding spring-and-autumn rearing silkworm varieties were analyzed using the procedure of breeding the hybrid of 873 × 874 as example.   <strong>REFERENCES </strong> He, S.M. et al. (1998). Breeding of summer-autumn using silkworm varieties 415 and 416 and the preparation of their hybrids. Acta Sericologica Sinica, 24, 215-220. He, S.M. et al. (1998). Breeding of vigorous and hypersilkgeneous silkworm varieties 871 and 872. Acta Sericologica Sinica, 24, 86-90. He, S.M. et al., (2000). Breeding of vigorous and hypersilkgeneous silkworm varieties 871 and 872. A report of the 9^th Five Year Plan on Silkworm Breeding. June 2000. https://cjes.guilan.ac.ir/article_980_93385d030ddce5d561ca1570b1502d37.pdf